taxonID	type	description	language	source
8F2387DD06120905FF31F997FBBBFBD0.taxon	materials_examined	Type genus. Orbinia Quatrefages, 1866, designated by Hartman 1942	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06120905FF31F997FBBBFBD0.taxon	diagnosis	Diagnosis. Body elongate, usually divided into a wide, dorsoventrally flattened thoracic region formed of firm, muscular segments, and a posterior abdominal region rounded in cross section and composed of soft, fragile segments bearing dorsally elevated parapodia, or abdominal parapodia not elevated; bodies usually with indistinct body regions, or body regions absent. Prostomium of variable shapes, with anterior margin ranging from acutely pointed to bluntly rounded; 1 – 2 pair of eyespots sometimes present, but usually absent; paired nuchal organs present. Proboscis soft, eversible, saclike without armature, sometimes dendritically branched when everted. Peristomium composed of 1 – 3 achaetous rings of which the first is a true peristomial segment, with second and third, when present representing achaetous segments (Fauchald & Rouse, 1997). Paired cirriform and ciliated branchiae located mid-dorsally between the notopodia, beginning either on or just posterior to thoracic region, continuing to posterior end; or branchiae entirely absent. Small dorsal sense organs sometimes present anterior to and medial to branchiae in some thoracic and abdominal parapodia. Notopodia simple, fingerlike postsetal lobes; sometimes divided or forked. Interramal cirri sometimes present between notopodia and neuropodia of posterior thoracic and / or abdominal segments. Neuropodia well developed in thoracic region, sometimes forming elevated ridges bearing numerous setae; one to many postsetal lamellae often present, sometimes continuing ventrally as additional stomach papillae. Abdominal neuropodia extending laterally and dorsally, usually bilobed; ventral cirrus often present; ventral flange may be present. Lateral organ sometimes present between noto- and neuropodia. Notosetae including capillaries, flail setae, and furcate setae; modified spines sometimes present in abdominal notopodia. Thoracic neurosetae may include crenulated capillaries, blunt-tipped crenulated setae, crenulated or smooth uncini, and modified spines; or any combination of capillaries, uncini, and spines. Abdominal neurosetae including capillaries and sometimes flail setae with hoods or mucrons on their tips; imbedded aciculae usually present; protruding present on some genera. Pygidium simple, collarlike, sometimes with several long filamentous anal cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06120905FF31F997FBBBFBD0.taxon	discussion	Remarks. This diagnosis is condensed from Hartman (1957) who provided the most comprehensive modern review of the family together with summaries of the historical literature. Hartman (1957) also diagnosed most of the genera and provided a comprehensive glossary of morphological terms. Readers are referred to Hartman’s monograph for further details. Apart from micromorphology now evident in the scanning electron micrographs, the morphological criteria defined by Hartman are still relevant. However, patterns of chaetogenesis of furcate and crenulated capillary setae in orbiniids revealed by Hausam & Bartolomaeus (2001) provide important clues for understanding the relationship of orbiniids with other polychaete families. Hoffman & Hausam (2007) analyzed the setal fascicle arrangement of orbiniids and found little similarity with other families suggesting another approach for using morphology to understand phylogeny among polychaete families. Further, several new setal characters have been identified in the present study that permit a finer resolution between species.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061D0905FF31FB8DFB49F9B0.taxon	materials_examined	Type genus. Orbinia Quatrefages, 1866, designated by Hartman 1957.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061D0905FF31FB8DFB49F9B0.taxon	diagnosis	Diagnosis. Body large, with distinct regions; parapodia lateral in thoracic region, typically shifted dorsally in abdominal region. Prostomium bluntly rounded to acutely pointed; nuchal organs present; eyespots present or absent. Peristomium with 1 – 2 achaetous rings, separated from prostomium. Noto- and neuropodial postsetal lamellae single, simple lobes to multiple lobes, sometimes branched; subpodial lobes and stomach papillae present or absent; interramal cirri present or absent. Setae including aciculae, capillaries, furcate setae, spines, uncini, modified spear-like setae, and flail setae. Branchiae typically present, rarely absent; branchiae usually single, rarely branched; oval to flattened, with two longitudinal rows of cilia and typical orbiniid structure with two blood vessels connected by numerous capillaries; branchiae of abdominal region thinner, more elongate than on thorax. Pygidium with several long filamentous anal cirri, or cirri absent. Inclusive genera. Berkeleyia, Califia, Leitoscoloplos, Leodamas, Naineris, Orbinia, Phylo, Protoaricia, Protoariciella (problematic, see below), Questa, Schroederella, Scoloplella, and Scoloplos.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061D0904FF31F92DFB83FD30.taxon	materials_examined	Type species: Berkeleyia profunda Hartman, 1971, Mozambique Basin, 4886 – 5069 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061D0904FF31F92DFB83FD30.taxon	diagnosis	Diagnosis. Prostomium pointed, conical; peristomium with one achaetous ring. Branchiae from posterior thoracic or abdominal segments. Thoracic noto- and neuropodia with one postsetal lobe, sometimes absent or inconspicuous on anteriormost setigers; subpodial lobes absent; abdominal setigers with simple noto- and neuropodia; neuropodia with or without ventral cirrus; interramal cirri absent. Thoracic noto- and neurosetae all capillaries. Abdominal notosetae include capillaries; pointed spines present or absent; furcate setae present or absent; neuropodia with capillaries and protruding acicular spines; or only spines.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061D0904FF31F92DFB83FD30.taxon	discussion	Remarks. The genus Berkeleyia was established by Hartman (1971) for a single species, B. profunda from abyssal depths in the Mozambique Basin. Berkeleyia is closely related to Leitoscoloplos in having only camerated capillaries in thoracic neuropodia. The two genera differ markedly, however, in that species of Berkeleyi a have well-developed acicular spines protruding from abdominal neuropodia and sometimes in abdominal notopodia. Five species of Berkeleyia are now known, all from the Southern Hemisphere and all but one are from abyssal depths; four new species have been encountered as part the present study:	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061D0904FF31F92DFB83FD30.taxon	description	B. abyssala n. sp. Antarctic seas, Drake Passage and Weddell Sea, 3111 – 4176 m. (See below). B. weddellia n. sp. Antarctic sea, Weddell Sea, 2164 m. (See below). B. hadala n. sp. Peru-Chile Trench, 3086 – 6143 m (See below). Berkeleyia heroae n. sp. differs from the four deep-water species in having the abdominal neuropodial spines with a distinctly bifurcated or notched tip, but otherwise all four of the new species and the type-species from the Mozambique Basin form a well-defined group within the Orbiniidae. An additional new deep-water species has been discovered on a seamount in the Atlantic Ocean and will be described separately.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061C0904FF31FCD7FCE3F834.taxon	materials_examined	Material examined. Argentina, Staten Island, off Tierra del Fuego, Hero Sta. 71 - 2 - 16, 27 Apr 1971, 54.773 ° S, 64.712 ° W, intertidal, low water, holotype (USNM 60633); Sta. 71 - 2 - 39, 24 Oct 1971, 54.797 ° S, 65.27 ° W, intertidal to 1 m, 3 paratypes (USNM 60634).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061C0904FF31FCD7FCE3F834.taxon	description	Description. Holotype complete, 9.5 mm long and 0.6 mm wide for 48 setigerous segments; largest paratype 9.7 mm long and 0.6 mm wide for 48 setigers. Color in alcohol: brown with several dark, diffuse pigment spots on prostomium. Thoracic region with 9 – 10 setigers, somewhat flattened dorsally; abdominal segments cylindrical in cross section. First 10 – 11 abdominal setigers with parapodia gradually shifted dorsally becoming fully shifted in middle and posterior setigers. Prostomium conical, more or less rounded on anterior end (Fig. 1 A); without eyespots. Peristomium about twice as long as subsequent setigers, with paired ciliated nuchal organs on anterolateral margin (Figs. 1 A, 2 A). Thoracic and abdominal notopodia similar throughout body, with short, papillate postsetal lobes (Fig. 1 A – B). Thoracic neuropodia similar to notopodia; abdominal neuropodia with short, conical lobe and low presetal lamella (Fig. 2 B). Thoracic parapodia with long crenulated capillaries. Abdominal notopodia with crenulated capillaries and 1 – 2 delicate furcate setae (Figs. 1 C, 2 E); furcate setae with 5 – 6 more or less basally fused, thin needles between tynes and rows of fine barbs on shaft (Fig. 1 D); with SEM, rows of barbs on shaft observed to merge with bases of needles and with both structures continuous (Fig. 2 E); tynes with tips bearing openings only visible with SEM (Fig. 2 E). Abdominal neuropodia with 2 – 3 capillaries and 2 – 3 projecting spines; each spine with bidentate forked tips and transverse rows of barbs shaft (Figs. 1 C; 2 C – D). Branchiae from abdominal setiger 19 – 24, continuing to posterior end (Fig. 1 B); anterior branchiae short, then becoming long, straplike. Pygidium with anus directed posteriorly located between two lobes, each bearing terminal anal cirrus (Fig. 1 B). Large elongate ova, approximately 75 µm in diameter, present in anterior abdominal segments of one paratype.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061C0904FF31FCD7FCE3F834.taxon	etymology	Etymology. The species is named for the R / V Hero, former research vessel of the National Science Foundation.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061C0904FF31FCD7FCE3F834.taxon	discussion	Remarks. Berkeleyia heroae n. sp. has abdominal neuropodial acicular spines with bifid tips, the parapodia are reduced, with only short, conical postsetal lobes, the prostomium is conical, yet rounded on the anterior margin and the thoracic region is slightly flattened instead of inflated. This species differs from the type species B. profunda as well as B. abyssala n. sp., B. weddellia n. sp., and B. hadala n. sp. (below) in having bidentate neuropodial acicular spines instead of unidentate.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061C0904FF31FCD7FCE3F834.taxon	distribution	Distribution. Argentina, Staten Island, intertidal to 1 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061F0900FF31F9BAFBE5FD2F.taxon	materials_examined	Material examined. Drake Passage, Eltanin Sta. 5 - 311, 3 Nov 1962, 57.98 ° S, 70.93 ° W., 3911 – 4099 m, holotype (USNM 56500); Sta. 5 - 303, 30 Oct 1962, 62.05 ° S, 70.92 ° W, 4077 – 4176 m, paratype (USNM 69340). — Weddell Sea, Glacier Sta. 69 - 22, 3111 m (1, USNM 46606); Eltanin Sta. 12 - 1063, 3495 – 3514 m (1, USNM 56524). — Powell Basin, off South Orkney Islands, ANDEEP III ANT XXII- 3, R / V Polarstern, Sta. PS- 67 / 142 - 7, 3406 m (1, SEM, JAB); Sta. PS- 67 / 150 - 8, 1942 m (1, SEM, JAB).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061F0900FF31F9BAFBE5FD2F.taxon	description	Description. All specimens incomplete; holotype 6.5 mm long and 0.7 mm wide for 19 setigerous segments; paratype 6.5 mm long and 0.4 mm wide for 17 setigers; Weddell Sea specimens larger, up to 17 mm long and 0.8 mm wide for 52 setigers. Body cylindrical throughout, not depressed anteriorly; thoracic region widest; abdominal setigers 2 – 3 times longer than thoracic (Fig. 3 A). Color in alcohol: light tan to opaque white. Prostomium conical, narrowing to pointed tip on anterior margin (Figs. 2 F, 3 A); without eyespots; nuchal organs on posterolateral margin of prostomium (Fig. 2 F). Peristomium achaetous, indistinctly separated from prostomium and setiger 1 (Figs. 2 F, 3 A). Thorax with 10 – 11 setigers, all of similar size; digitiform postsetal lobes present from setiger 4 (Fig. 3 A). Abdominal notopodia with long, fingerlike postsetal lobes; neuropodia prolonged, expanded subdistally, with short ventral cirrus (Fig. 3 B). All thoracic parapodia with crenulated capillaries; capillaries with transverse rows of short barbs (Fig. 2 G). Abdominal notopodia with long and short crenulated capillaries and 2 – 3 furcate setae; furcate setae with subequal tynes connected by row of fine needles and thin webbing, shaft with vertical rows of minute barbs (Fig. 3 C). Abdominal neuropodia with 2 – 3 short, smooth spines (Fig. 3 D) and 3 – 6 long, thin, non-crenulated capillaries (Fig. 2 G). Branchiae from setiger 9 – 10 or next-to-last thoracic setiger (Figs. 2 F, 3 A); each branchia short, subtriangular (Fig. 3 B).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061F0900FF31F9BAFBE5FD2F.taxon	etymology	Etymology. The epithet is derived from abyssus, Latin for deep sea.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061F0900FF31F9BAFBE5FD2F.taxon	discussion	Remarks. Berkeleyia abyssala n. sp., B. weddellia n. sp. (see below), and type-species B. profunda, all from abyssal depths differ from the shallow water B. heroae n. sp. in having the abdominal neuropodial spines with entire tips instead of bidentate. B. abyssala n. sp. differs from B. weddellia n. sp. and B. profunda in having branchiae from posterior thoracic setigers instead of abdominal segments. In B. abyssala n. sp. branchiae are present from setigers 9 – 10 whereas they are present from setiger 18 in B. weddellia n. sp., not stated in B. profunda, but not illustrated before setiger 14 in Hartman (1978). Berkeleyia abyssala n. sp. also differs from the other three species in having narrow thoracic segments and elongated abdominal segments; both B. abyssala n. sp. and B. weddellia n. sp. have a ventral cirrus on abdominal neuropodia, but this is longer and more conspicuous in B. abyssala n. sp.. Abdominal neuropodial spines are similarly pointed in B. abyssala n. sp. and B. weddellia n. sp., but blunt-tipped in B. profunda.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD061F0900FF31F9BAFBE5FD2F.taxon	distribution	Distribution. Antarctic and subantarctic seas, abyssal depths of 3111 – 4176 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06180900FF31FCAFFCFBF91E.taxon	materials_examined	Material examined. Antarctica, Weddell Sea, ANDEEP III, R / V Polarstern, Sta. PS 67 / 078 - 4, 21 Jan 2005, 71 ° 9.49 ′ S, 13 ° 59.92 ′ W, 2164 m, holotype (ZMH P- 27782).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06180900FF31FCAFFCFBF91E.taxon	description	Description. A single incomplete specimen 4 mm long, 0.4 mm wide across thorax for 28 setigers. Color in alcohol: light tan, without pigment. Thoracic region with 11 setigers; body cylindrical in cross section, weakly flattened dorsally, abdominal segments cylindrical in cross section. Prostomium conical, triangular in shape, tapering to narrow pointed apex (Fig. 4 A – B); without eyespots; nuchal organs paired notches on anterior margin of peristomium (Fig. 4 A). Peristomium with a single achaetous ring, slightly narrower than setiger 1, but similar in length. Thorax with short, conical notopodial postsetal lobes from setiger 1, increasing in length and shape over thoracic region, initially minute, rounded, then becoming triangular at base narrowing to pointed apex by setiger 8 (Fig. 4 A); neuropodia similar to notopodia with elongate postsetal lobe with triangular base near end of thoracic region; abdominal segments denoted by shift of parapodia dorsally, and abrupt change in notopodia to long, narrow, fingerlike postsetal lobe (Fig. 4 C); abdominal neuropodia becoming thickened, with short ventral cirrus (Fig. 4 C). Thoracic setae all long, crenulated capillaries; abdominal notopodia with crenulated capillaries and 1 – 2 delicate furcate setae; each furcate seta with 5 – 6 thin needles between tynes and rows of fine barbs on shaft (Fig. 4 D). Abdominal neuropodia with 2 – 3 capillaries and 2 – 3 long projecting smooth spines with entire pointed tips (Fig. 4 C, E – F). Branchiae from setiger 18, short at first, becoming full size by setiger 20, each branchia thick, short with rounded apex (Fig. 4 C). Pygidium unknown.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06180900FF31FCAFFCFBF91E.taxon	discussion	Remarks. See comments under B. abyssala n. sp.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06180900FF31FCAFFCFBF91E.taxon	etymology	Etymology. This species is named for the collecting locality in the Weddell Sea, Antarctica.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06180900FF31FCAFFCFBF91E.taxon	distribution	Distribution. Weddell Sea Basin, Antarctica, 2164 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0618091DFF31F8D9FEE5FCBF.taxon	materials_examined	Material examined. Off Western South America, Peru-Chile Trench. — Off Ecuador, R / V Vema Sta. V- 15 - 63, 2681 - 2864 m (1, LACM-AHF Poly 5009). — Off Piura Province, Peru, W of Isla Lobos de Tierra, R / V Anton Bruun Cruise 11, Sta. 69, Milne-Edwards Deep, 4591 m (1, LACM-AHF Poly 5015). — Off Libertad Province, Peru, W of Trujillo, R / V Anton Bruun Cruise 11, Sta. 98, Milne-Edwards Deep, 6052 – 5989 m (2, LACM-AHF Poly 5012); Sta. 111, Milne-Edwards Deep, 3086 – 3202 m, 18 Oct 1965, 08 ° 23 ' S, 80 ° 45 ′ W, 1 paratype (LACM- AHF Poly 5016); Sta. 113, Milne Edwards Deep, 19 Oct 1965, 08 ° 44 ' S, 80 ° 45 ′ W, 5986 – 6143 m, 14 paratype s, (LACM-AHF Poly 5019). — Off Chile, W of Isla Mocha, R / V Vema Sta. V- 17 - 5, 16 Mar 1961, 38.25 ° S, 76.00 ° W, 3824 – 3739 m, 1 paratype (LACM-AHF Poly 5040); Sta. V- 17 - 6, 21 Mar 1961, 37.95 ° S, 75.13 ° W, 4303 – 4323 m, holotype (LACM-AHF Poly 5001); Sta. V- 17 - 7, W of Bahia Mansa, 22 Mar 1961, 40 ° 32 ′ S, 75 ° 08 ′ W, 3089 – 3279 m, 1 paratype (LACM-AHF Poly 5039).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0618091DFF31F8D9FEE5FCBF.taxon	description	Description. All specimens incomplete, many poorly preserved; holotype 15 mm long, 1 mm wide across thorax for 34 setigers; other specimens with 19 – 30 setigers, up to 16 mm long and 1.1 to 0.8 mm wide across thorax. Color in alcohol: opaque white, without pigment. Holotype with 11 thoracic setigers; other specimens with 8 – 11 thoracic setigers; body cylindrical in cross section, throughout; thoracic segments narrower than wide, middle and posterior abdominal segments elongate, longer than wide. Shape of pre-setigerous region distinctive in dorsal view (Fig. 5 A), with an hour-glass shape; prostomium triangular shaped merging indistinctly with narrow anterior of peristomium, becoming wider in posterior half. Prostomium tapering to narrow pointed apex (Fig. 5 A); without eyespots; nuchal organs paired notches on posterior margin of prostomium at juncture with peristomium (Fig. 5 A). Peristomium with a single achaetous ring, narrow anteriorly, wider posteriorly. Thoracic segments with short cirriform notopodial postsetal lobes from setiger 1, these increasing in length over subsequent setigers becoming elongate and fingerlike in posterior thoracic setigers (Fig. 5 B); neuropodia similar to notopodia with elongate postsetal lobe (Fig. 5 B); abdominal segments denoted by appearance of prolonged neuropodium bearing long, brass-colored spines (Fig. 5 C); abdominal notopodia initially without postsetal lobe, this appearing over subsequent setigers, becoming elongate, fingerlike in far posterior setigers (Fig. 5 C). Abdominal segments with parapodia gradually shifting to a more dorsal position. Thoracic setae all long, crenulated capillaries; furcate setae absent. Abdominal neuropodia with 3 – 4 long projecting smooth brass-colored spines with entire rounded tips (Fig. 5 C, E); abdominal notopodia with similar brass-colored long spinous setae, but with pointed capillary tips (Fig. 5 D). No abdominal camerated setae. Branchiae from setiger 24 on holotype, short, cirriform and inconspicuous at first, elongating and becoming slightly longer than notopodial postsetal lobe by setiger 34; branchiae slightly swollen on medial border (Fig. 5 C). Branchiae not observed on other specimens, likely due to poor preservation and their fragmented nature. Pygidium unknown.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0618091DFF31F8D9FEE5FCBF.taxon	discussion	Remarks. Among the five known species of Berkeleyia, B. hadala n. sp. is unique in the Orbiniidae in having a complete transition from typical orbiniid-like camerated capillaries in thoracic setigers to non-camerated and conspicuous brass-colored smooth setae in abdominal segments. The neurosetae are elongate, thickened blunttipped spines, whereas the notosetae are similarly appearing elongate and thickened setae, but with pointed tips.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0618091DFF31F8D9FEE5FCBF.taxon	etymology	Etymology. This species is named for its occurrence in abyssal to ultra-abyssal depths in the Peru-Chile Trench; trench faunas are sometimes called residents of the Hadal Zone.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0618091DFF31F8D9FEE5FCBF.taxon	distribution	Distribution. Off western South America, Ecuador to Chile, lower slope, abyssal and ultra-abyssal depths 2681 – 6143 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0605091CFF31FC3FFC2AFF70.taxon	diagnosis	Diagnosis. Prostomium pointed, conical; peristomium typically with one achaetous ring, but with additional superficial annulae on some species. Branchiae lacking, or present from posterior thoracic, transitional, or abdominal setiger. Posterior thoracic setigers with 0 – 2 postsetal lobes and 0 – 2 subpodial lobes; abdominal setigers with 0 – 4 subpodial papillae; stomach papillae rare, interramal cirri present or absent. Thoracic neurosetae including only capillaries. Without abdominal neuropodial spines, with 2 – 3 imbedded aciculae present or absent.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0605091CFF31FC3FFC2AFF70.taxon	discussion	Remarks. Day (1977) determined that the type species of Haploscoloplos Monro, 1933 a (H. cylindrifer (Ehlers, 1904 )) possessed an anterior row of short hooks in the thoracic neuropodia in addition to capillaries and thus belonged to the genus Scoloplos. He examined a specimen from near Christchurch, NZ; South Island, New Zealand, near the type locality of the species. He therefore proposed a new genus, Leitoscoloplos to include those remaining species formerly assigned to Haploscoloplos. Most of the known species of Leitoscoloplos were summarized by Mackie (1987). Those species have been reconsidered as part of this study. Several new species, new combinations, and new synonymies are proposed from the materials examined as part of this study and are listed below. An assessment of branchial distribution suggests that Leitoscoloplos can be divided into five groups of species. Geographically, species within these groups also have some affiliation to their distribution globally. For example, the two abranchiate species in Group A are deep-sea abyssal species; the three species in Group C occur only along the Atlantic and Gulf coasts of North America, and all 11 species in groups D and E occur in the southern hemisphere of which seven occur in the Southern Ocean. The 11 species in Group B are the most ubiquitous, occurring widely over the world’s oceans. This study suggests that previous records of certain widely recorded species need to be reevaluated. For example, the record of Haploscoloplos kerguelensis from the eastern Mediterranean by Ramos (1976) is most certainly an undescribed species (see Discussion of L. kerguelensis below). Similar identifications of Haploscoloplos or Leitoscoloplos kerguelensis from Asia also need to be reconsidered (see below). One undescribed deep-sea species of Leitoscoloplos was recently identified from offshore Brunei Darussalam in the South China Sea (Blake unpublished). According to this revision, Leitoscoloplos species are categorized as follows:	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0604091FFF31F9FFFCA4FD67.taxon	materials_examined	Material examined: Scotia Sea, West Scotia Basin, Falkland Islands, Eltanin Sta. 6 - 350, 2452 m, Menzies trawl (3, USNM 56455). — off Cape Horn, Eltanin Sta. 4 - 112, 20 Jul 1962, 55.52 ° S, 61.92 ° W, 4008 m, holotype and 7 paratypes, (USNM 55531 – 2). — off Tierra del Fuego, R / V Vema Sta. V- 17 - 56, 4006 m, (1, LACM-AHF Poly 5010) — South Shetland Islands, Eltanin Sta. 4 - 138, 1437 m (3, USNM 56454). — off South Georgia, Eltanin Sta. 9 - 711, 2983 – 3331 m (1, USNM 60630). — Drake Passage, Eltanin Sta. 9 - 740, 384 – 494 m (1, USNM 61944). — South Orkney Islands, Eltanin Sta. 6 - 1082, 298 – 302 m (1, USNM 60631). — Weddell Sea, Antarctica, Glacier Sta. 69 - 21, 2288 m (1, USNM 61945). — Weddell Sea, ANDEEP III ANT XXII- 3, R / V Polarstern, Sta. PS- 67 / 078 - 6, 2168 m (1, SEM, JAB); Weddell Sea, abyssal plain, ANDEEP SYSTCO ANT XXIV- 2, R / V Polarstern, Sta. 33 - 14, 5338 m, 6 specimens (ZMH P- 27794). — South Pacific Ocean, Albatross Cordillera, Eltanin Sta. 14 - 1250, 3638 – 3825 m (2, USNM 60632).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0604091FFF31F9FFFCA4FD67.taxon	description	Description. A small species, up to 18 mm long, 1.0 mm wide for about 30 setigerous segments. Prostomium conical, narrowly rounded on anterior margin (Fig. 6 A); peristomium deeply folded, with 2 – 3 superficial annuli. Thoracic region with 9 – 13 setigers. Thoracic parapodia with short, conical noto- and neuropodial postsetal lobes. Abdominal parapodia only weakly elevated dorsally; with short, fingerlike notopodial postsetal lobes; neuropodia flattened, prolonged, rectangular in shape, distally entire (Fig. 6 B). Thoracic parapodia with fascicles of long crenulated capillaries; abdominal notopodia with capillaries and 1 – 2 furcate setae, each with unequal tynes connected by row of thin needles (Fig. 6 C). Branchiae entirely absent. Pygidium unknown.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0604091FFF31F9FFFCA4FD67.taxon	discussion	Remarks. This species was well described by Hartman (1967) and is illustrated here for the first time. Leitoscoloplos abranchiatus is readily differentiated from related forms by the numerous long, silky appearing capillaries of the thoracic region, the complete absence of branchiae, and abdominal parapodia that are lateral or only weakly elevated.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0604091FFF31F9FFFCA4FD67.taxon	distribution	Distribution. Subantarctic and Antarctic seas, 1400 – 5338 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0607091FFF31FD17FD5CF88D.taxon	materials_examined	Material examined. North equatorial Pacific Ocean, abyssal plain, Clarion-Clipperton Fracture Zone, NOAA BIE Sta. DDT- 08 - 93, 0 2 September 1993, 12 ° 55.633 ′ N, 128 ° 36.011 ′ W, 0.25 m 2 box core, 4843 m, coll. D. T. Trueblood, holotype (USNM 1407119).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0607091FFF31FD17FD5CF88D.taxon	description	Description. Holotype incomplete, 5.5 mm long, 0.6 mm wide across thorax for 22 setigers. Body cylindrical in cross section; parapodia lateral, abdominal parapodia only partially elevated dorsally. Thoracic and anterior abdominal segments about 4.5 x as wide as long; more posterior abdominal segments about as long as wide. Thorax with eight setigers, transition to abdominal segments evident by enlargement of neuropodium and development of a ventral cirrus. Branchiae entirely absent from fragment. Pygidium unknown. Color in alcohol, light tan; no body pigment. Prostomium conical, wide, basally tapering to rounded anterior margin; without eyespots, nuchal organs not observed (Fig. 6 D). Peristomium a single ring, wider than long, about 1.5 x as long as anterior thoracic setigers. Thoracic notopodia enlarged, somewhat swollen, with narrow, finger-like postsetal lobe which becomes wider basally and more triangular in shape along thoracic segments (Fig. 6 D); thoracic neuropodia not as large as notopodia (Fig. 6 D); postsetal lamellae absent on setiger 1, short, fingerlike postsetal lobe present from setiger 2 and continuing through thoracic setigers (Fig. 6 D); abdominal neuropodia enlarged, elongate, swollen apically with short, ventral cirrus., only partially elevated dorsally (Fig. 6 E). Thoracic noto- and neurosetae long crenulated capillaries in dense fascicles of 75 or more setae. Notosetae of first 2 – 3 abdominal setigers similar to thoracic segments with dense fascicles of long capillaries; subsequent abdominal segments with fewer and shorter capillaries, reduced in number to 20 – 25 per notopodium (Fig. 6 D – E). Abdominal neurosetae few, reduced to 4 – 6 very fine capillaries; 1 – 2 embedded aciculae present (Fig. 6 E).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0607091FFF31FD17FD5CF88D.taxon	etymology	Etymology. The species name is from the Latin simplex and refers to the overall lack of typical orbiniid morphology.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0607091FFF31FD17FD5CF88D.taxon	discussion	Remarks. Leitoscoloplos simplex n. sp. is similar to L. abranchiatus in lacking branchiae, having long capillary setae in dense fascicles, and by having abdominal parapodia only weakly elevated instead shifted dorsally as in most orbiniids. These two deep-sea species differ in that L. simplex n. sp. has a peristomium with a large single ring instead of 2 – 3 weak lobes, has ventral cirri in abdominal neuropodia instead of lacking them, and most significantly, lacks furcate setae that are present in L. abranchiatus.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0607091FFF31FD17FD5CF88D.taxon	distribution	Distribution. Abyssal Pacific, 4843 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06010918FF31FF7CFB92FE34.taxon	materials_examined	Material examined. Chile, Punta Iloca, 34 ° 56 ′ S, 72 ° 14 ′ W, 5 Mar 1960, 50 m, fine sand with detritus, holotype of Haploscoloplos kerguelensis chilensis (ZMH-P- 14863); Seno Reloneavi, the Bay off Puerto Montt, N of the light buoy NE of Isla Tengo, LUCE Sta. M- 4 A, 13 – 16 m (2, SMNH 154442); Canal Chacao, Bahía de Ancud, Lechagua, LUCE Sta. M- 11 A, intertidal (1, SMNH 154437); Golfo de Ancud, SW of Isla Tabon, LUCE Sta. M- 44 A, ca. 200 m (3, SEM, JAB); Golfo Ancud, northern part, Canal San Antonio, LUCE Sta. M- 108, 60 m, (1, SMNH 154441); off Valparaiso, Eltanin Sta. 21 - 194, 137 – 141 m (4, USNM 69383). — Straits of Magellan, east of Isla Dawson, R / V Vema Sta. V- 17 - 23, 273 – 280 m (2, LACM-AHF Poly 5003). Comparative material examined. California, numerous specimens of Leitoscoloplos pugettensis from California (Bodega Harbor, Tomales Bay and Gulf of the Farallones) and Canada (Prince Rupert, British Columbia), intertidal to 50 m (JAB).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06010918FF31FF7CFB92FE34.taxon	description	Description. One complete specimen 24 mm long, 1.2 mm wide for 150 setigerous segments; other specimens up to 40 mm long and 2.0 mm wide for about 90 setigers; with 13 – 16 thoracic setigers. Color in alcohol: light tan. Prostomium conical, tapering to narrow anterior tip; without eyespots (Fig. 7 A). Peristomium wider than long, with pair of nuchal organs on anterior lateral margin. Two specimens from Strait of Magellan with multi-lobed proboscis everted. Thoracic notopodia with narrow elongate triangular-shaped postsetal lamella; thoracic neuropodia with elongate postsetal lamellae arising from prominent cushion or mound (Fig. 7 B); abdominal segments with leaflike, subtriangular notopodial postsetal lamellae (Fig. 7 C – D); neuropodia simple, bifid on tip, but lacking ventral cirrus (Fig. 7 D), with prominent inflated subpodial flange present ventral to neuropodia throughout abdominal region (Fig. 7 C – D); subpodial lobes absent. Thoracic noto- and neurosetae and abdominal neurosetae all crenulated capillaries, with crenulations consisting of numerous transverse rows of barbs (Fig. 7 H); abdominal notosetae including capillaries and furcate setae; furcate setae with two blunt-tipped unequal tynes connected by delicate rows of fine needles within a membrane; barbs not apparent on shaft (Fig. 7 F); with SEM, tips of tynes with opening (Fig. 7 G). Abdominal neurosetae smooth, not camerated, including separate dorsal fascicle of long, thin capillaries and a more ventral fascicle of 3 – 4 fine flail setae, not evident in middle and posterior abdominal neuropodia; flail setae curved, capillary tipped, difficult to see with light microscopy (Fig. 7 C-inset). Branchiae first present from setiger 13 – 16; anterior branchiae short, narrow, tapering to pointed tip; increasing in size posteriorly, with abdominal branchiae about twice as long as notopodial lobes; each branchia with distinct subapical flaglike lateral swelling (Fig. 7 C – D). Pygidium with four lobes surrounding terminal anus; two long anal cirri present (Fig. 7 E).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06010918FF31FF7CFB92FE34.taxon	discussion	Remarks. Haploscoloplos kerguelensis chilensis was raised to full species status by Mackie (1987). Leitoscoloplos chilensis appears to be most similar to L. pugettensis in numbers of thoracic setigers, general appearance of the parapodia, and form of the branchiae. The species is characterized by having branchiae first present from one of the last thoracic setigers. Each branchia has a subapical flaglike swelling directed laterally. The abdominal neuropodial lobes are bifid and a long, conspicuous subpodial flange is present. Initially, I considered that the Chilean specimens might be conspecific with L. pugettensis. However, careful study of the parapodia suggested otherwise. Leitoscoloplos chilensis has 13 – 16 thoracic setigers and branchiae from about setigers 12 – 16; L. pugettensis has 14 – 20 setigers with branchiae from setigers 13 – 18. The greater number of thoracic setigers and greater range of branchial initiation in L. pugettensis may, however, be due to much larger specimens being recorded (Hartman 1957; Pettibone 1957; Blake 2000). The branchiae of both species have distal expansions that in L. chilensis are directed laterally and fully swollen in both directions in L. pugettensis. More important differences are with the thoracic parapodia where the neuropodial postsetal lamellae of L. chilensis are longer, more triangular in shape; these are shorter and more papillate than L. pugettensis. The short interramal papilla in anterior abdominal segments of L. chilensis is difficult to observe and has not been reported for L. pugettensis. The discovery of flail setae in the anterior abdominal neuropodia of L. chilensis prompted an examination of L. pugettensis and these minute setae were also present in specimens examined from British Columbia (Blake unpublished) and Costa Rica (Dean & Blake 2015: Fig. 6 B). To date these are the only known examples of flail setae in the genus Leitoscoloplos. The very close similarity of L. pugettensis and L. chilensis suggest a cline between a single wide ranging Eastern Pacific species. The main differences are with the branchial morphology and details of the thoracic neuropodial lamellae. Differences in numbers of thoracic setigers and initiation of the branchiae are likely size related with larger specimens only available for L. pugettensis. The current distribution of L. pugettensis is from Alaska to Costa Rica (Blake 1996; Dean & Blake 2015); L. chilensis has not been recorded north of Chile.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06010918FF31FF7CFB92FE34.taxon	distribution	Distribution. Western Chile, intertidal to 50 m; Straits of Magellan, 273 – 280 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06030914FF31FF7CFF2FFA5F.taxon	materials_examined	Material examined. Chile, South Pacific Ocean, W of Isla Guafo, R / V Vema Sta. V- 17 - 10, 397 - 501 m, (2, LACM- AHF Poly 5038). — Straits of Magellan, R / V Vema Sta. V- 17 - 18, 248 - 262 m (2, LACM-AHP Poly 5002); East of Isla Dawson, R / V Vema Sta. V- 17 - 23, 273 – 280 m (3, LACM-AHF Poly 5003). — South Atlantic, SE of Falkland Islands, R / V Vema Sta. V- 14 - 12, 361 m (1, LACM-AHF Poly 5029). — N of South Georgia, Eltanin Sta. 9 - 732, 220 – 265 m (1, USNM 56507); Sta. 9 - 734, 1299 – 1400 m (1, USNM 56508). — South Georgia, off Cumberland Bay, 54 ° 11 ′ S, 36 ° 18 ′ W, Swedish Antarctic Expedition, Sta. 34, 252 – 310 m, syntype of Haploscoloplos kerguelensis minutus (SMNH 3703). — East Antarctic Peninsula, Prince Gustav Channel, RVIB Nathaniel B. Palmer, Station NBP- 35, 64 ° 10.471 ′ S, 058 ° 505 ′ W, 25 May 2000, Smith McIntyre grab, 651 m, (1, JAB) — South Orkney Islands, Eltanin Sta. 7 - 500, 489 – 490 m (1, USNM 56505); Sta. 14 - 1079, 593 – 598 m (1, USNM 56525); Sta. 12 - 1082, 298 – 302 m (2, USNM 56526); Sta. 12 - 1084, 298 – 403 m (12, USNM 56527). — South Shetland Islands, Hero Sta. 721 - 726 (1, USNM 60170); Sta. 721 - 742 (2, USNM 60169); Sta. 721 - 758 (2, USNM 60172); Sta. 721 - 964 (1, USNM 60166); Sta. 721 - 972 (3, USNM 60158); Sta. 1032 (1, USNM 60167); Eltanin Sta. 6 - 418, 311 – 426 m (1, USNM 56501); Eastwind Sta. 0 44, 19 Feb 1966, 62 ° 11 ′ S, 57 ° 49.5 ′ W, 747 m, coll. D. Pawson and D. Squires (1, USNM 69350); off Smith Island, R / V Vema Sta. V- 17 - 43, 21 Apr 1961, 655 – 673 m (9, LACM-AHF-Poly 5037). — Bransfield Strait, Eltanin Sta. 6 - 410, 220 – 240 m (14, USNM 56521); Sta. 6 - 428, (1, USNM 56502); Sta. 6 - 437, 267 – 311 m (5, USNM 56503). — West Antarctic Peninsula, Hero Sta. 1120 (26, USNM 69381); Eltanin Sta. 5 - 272 (1, USNM 56499); Sta. 6 - 439 (8, USNM 56504); off Adelaide Island, Eastwind Sta. 004 A, 24 Jan 1966, 67 ° 53 ′ S, 069 ° 10 ′ 30 ″ W, 330 m, coll. D. Pawson and D. Squires (12, USNM 69349). — Ross Sea, McMurdo Sound, W of Inaccessible Island, Deep-Freeze II, Glacier Sta. 2, 420 m (2, USNM 1013658). — Weddell Sea, Glacier Sta. 68 - 1, 650 m (12 USNM 46601); Sta. 69 - 8, 585 m (2, USNM 46605).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06030914FF31FF7CFF2FFA5F.taxon	description	Description. A moderate-sized species, up to 30 mm long and 2 mm wide for about 100 setigers; average size 14 mm long and 0.9 mm wide for about 65 setigers. Color in alcohol: brown. Thoracic region inflated, not depressed, with 8 – 10 setigers, slightly wider than abdominal region (Figs. 8 A, 9 A). Prostomium short, conical, pointed, but not acute on tip (Fig. 8 A); two nuchal slits sometimes apparent in dorsolateral locations; without eyespots. Peristomium a single achaetous ring, twice as long as setiger 1 (Fig. 8 A). Thoracic parapodia all similar, inconspicuous; notopodia with short, triangular-shaped postsetal lobes, narrow at first, then becoming thicker in last thoracic setigers (Figs. 8 B, 9 A); neuropodia with papillate postsetal lobe arising from basal cushion (Fig. 8 B). Abdominal notopodia with thin, narrow, fingerlike postsetal lobes and single, thickened, elongated neuropodia (Figs. 8 C, 9 C – D), sometimes with apical notch, never strongly bifurcated (Fig. 8 C). Subpodial flange small, but inflated, continuous with neuropodial lobe (Figs. 8 C, 9 C – D). Branchiae from setiger 13 – 17, short at first, increasing in length posteriorly. Branchiae more or less symmetrical, sometimes curved towards dorsal mid-line (Fig. 8 C). Thoracic setae including crenulated capillaries; neurosetae arising from broad cushion, in two rows, with some capillaries of first row short, thin, straight; setae of second row longer, thicker, and curved (Fig. 9 B); notosetae similarly arranged. Abdominal notosetae including crenulated capillaries and furcate setae; in light microscope, furcate setae observed with unequal tynes connected by membrane of fine needles (Fig. 8 D – E), with SEM 7 – 8 needles observed, individually with sharp tapering tips, lateral needles merging with tynes; tips of tynes expanded, with distinct apical opening (Fig. 9 E). Abdominal neurosetae thin, weakly crenulated; aciculae sometimes with tip emergent. Pygidium a simple ring, lacking cirri (Fig. 9 D).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06030914FF31FF7CFF2FFA5F.taxon	discussion	Remarks. Leitoscoloplos kerguelensis belongs to a group of species with branchiae from anterior abdominal setigers. This species includes individuals having 8 – 10 thoracic setigers and branchiae from setiger 13 – 17. Specimens having branchiae from earlier setigers or from setiger 18 or more posteriorly are here referred to other species (see below). There are numerous records of L. kerguelensis globally, but the species is here restricted to sub-Antarctic and Antarctic locations; some Antarctic and sub-Antarctic records are referred to other species. Leitoscoloplos kerguelensis has, rather than lacks furcate setae (as sometimes stated) and the prostomium is more elongate than its closest relatives. In Antarctica, L. kerguelensis is most closely related to L. geminus and L. mawsoni, differing primarily in having branchiae from setiger 13 – 17 instead of 10 – 12. There are further differences in details of the abdominal neuropodia, shape of the posterior branchiae, and general shape of the prostomium. There may also be important differences in details of the structure of the furcate setae, but further study is needed. However, all three species are similar and separated with difficulty. Both L. geminus and L. mawsoni are limited to relatively shallow waters, ca. 0 – 200 m, whereas L. kerguelensis has been collected from the intertidal to 1400 m, and occurs frequently in samples along the Antarctic Peninsula from 500 – 600 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06030914FF31FF7CFF2FFA5F.taxon	biology_ecology	Biology. Despite being one of the most common orbiniids in Antarctica and certain subantarctic locations, little information is available on the biology of this species. Averincev (1982) identified Leitoscoloplos kerguelensis (as Haploscoloplos) from shallow sites in the Davis Sea, an area off the coasts of Queen Mary Land and Wilhelm II Land, between the Shackleton Ice Shelf and the West Ice Shelf. Russian scientists have maintained research facilities in the area since the 1960 s. As part of annual collections from subtidal collections in depths of 3 – 45 m, Averincev (1982) concluded that the life cycle of this species was short with a one-time recruitment in January – February and a life span of approximately one year. Abundance and biomass ranged from 10 – 400 specimens per m 2 with a biomass of 0.12 to 4 g / m 2.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06030914FF31FF7CFF2FFA5F.taxon	distribution	Distribution. Widespread in Antarctic and subantarctic seas: Strait of Magellan, South Georgia, Kerguelen Islands, South Orkney Islands; South Shetland Islands; Antarctic Peninsula; Ross Sea; Weddell Sea. Intertidal to 1400 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060C0916FF31FA19FAF1FE6D.taxon	materials_examined	Material examined. Uruguay, off the mouth of the Rio de la Plata, IBM Sta. N- 242, 63 m (2, USNM 1013639); Sta. N- 260, 144 m (1, USNM 1013638); Sta. N- 1073, 115 – 117 m (3, USNM 1013637); Sta. 1074, 35 ° 29 ′ S, 53 ° 01 ′ W, 112 m, holotype and 2 paratypes (USNM 1013633 – 4); Sta. N- 1075, 68 m (1, USNM 1013636). — Argentina, IBM Sta. N- 1059, 35 ° 25.9 ′ S, 53 ° 27.9 ′ W, 72 – 80 m, 14 paratypes (USNM 1013635); Golfo San Matías, SAO- 1, Sta. 51, 41 ° 08.30 ′ S, 65 ° 06.30 ′ W, intertidal in gravel, coll. IBM (1, USNM 1013640).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060C0916FF31FA19FAF1FE6D.taxon	description	Description. A small species, holotype complete, approximately 13 – 14 mm long (posterior end coiled) and 0.8 mm wide for about 100 setigers. Color in alcohol: brown. Thoracic region with first 4 – 5 setigers weakly inflated, not depressed, with 9 – 10 setigers, similar in width to anterior abdominal segments (Figs. 9 E, 10 A). Prostomium short, conical, pointed, and narrow (Figs. 9 F, 10 A); two nuchal slits sometimes apparent in dorsolateral locations (Fig. 9 F); without eyespots. Peristomium a single triangular-shaped achaetous ring, narrower, but longer than setiger 1; with prostomium forming triangular “ head. ” Thoracic parapodia all similar, inconspicuous, with elongated postsetal lobes, with notopodia short, triangular in shape (Fig. 10 B); neuropodia with low basal cushion from which digitiform postsetal lobe emerges; postsetal lamellae short, narrow at first, becoming longer and thicker in last thoracic setigers. Abdominal notopodia with thin, narrow, fingerlike postsetal lobes; abdominal neuropodial lobes elongate, thickened apically with distinct ventral cirrus; subpodial flange small but distinct, continuous with neuropodial lobe (Fig. 10 C – D). Branchiae from setiger 13 – 16, short, triangular at first (Fig. 10 A, C), then increasing in length posteriorly (Fig. 10 D); branchiae asymmetrical, with large protruding lateral lobe (Fig. 10 C – D). Thoracic setae crenulated capillaries in dense fascicles with two rows of 20 – 25 setae per fascicle, arising from broad cushion (Fig. 10 B); setae of first row shorter and thinner than those of second row. Abdominal notosetae including 8 – 9 capillaries and 0 – 2 furcate setae; furcate setae with unequal tynes connected by row of fine needles; both tynes with rounded tips, shaft with ribbed crenulations (Fig. 10 E). Abdominal neurosetae including 2 – 3 long, smooth or weakly crenulated capillaries and 1 – 2 short, protruding, curved, blunt-tipped aciculae (Fig. 10 C). Pygidium a smooth, enlarged ring, lacking cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060C0916FF31FA19FAF1FE6D.taxon	etymology	Etymology. This species is named for its proximity to the Rio de la Plata.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060C0916FF31FA19FAF1FE6D.taxon	discussion	Remarks. Leitoscoloplos plataensis n. sp. is closely related to L. kerguelensis in having 9 – 10 thoracic setigers and branchiae from setigers 13 – 16. Leitoscoloplos plataensis n. sp. differs in having the abdominal branchiae with a large protruding lateral lobe, ventral cirri on the abdominal neuropodia, and a different shape to the prostomium and peristomium. Further, furcate setae are rarely found in both the thoracic and abdominal notopodia of L. plataensis n. sp. but are commonly in the notopodia of L. kerguelensis.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060C0916FF31FA19FAF1FE6D.taxon	distribution	Distribution. Known only from off Uruguay and Argentina, intertidal to 144 m in coarse sediments.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060E0911FF31FE14FB85F874.taxon	materials_examined	Material examined. Antarctica: Adelie Land, Commonwealth Bay, Boat Harbor, 67 ° 00 ′ S, 142 ° 36 ′ E, 8 m, coll. J. Haswell, 15 Oct 1912, 55 syntypes (AM W 769). — Wilkes Land, Vincennes Bay, Casey Station, coll. Australian Antarctic Division, Brown Bay, middle, Sta. S 1 P 1 R 1, 0 4 Dec 2005, 66.272 ° S, 110.567 ° E, diver cores, 15 – 25 m, (50, including 15 juveniles, AM); O’Brien Bay- 1, T 2 P 1 R 2, 14 Dec 2006, 66.312 ° S; 110.515 ° E, diver cores, 12 – 25 m, (24, AM); Wilkes Bay, Sta. S 2 P 1 R 3, 15 Dec 2005, 66.526 ° S; 110.526 ° E, diver cores, 10 – 20 m, (26, including 10 juveniles, AM); Sta. S 1 P 2 R 3, 15 Dec 2005, 66.526 ° S; 110.526 ° E, diver cores, 10 – 20 m, (44, AM).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060E0911FF31FE14FB85F874.taxon	description	Description. A moderate-sized species, syntypes up to 32 mm long, 1.5 mm wide for about 100 setigers; other specimens with similar maximal measurements. Color in alcohol: light tan; large specimens from Casey Station S 1 P 1 R 1 with dusky dark pigment on prostomium, peristomium, and first 3 – 4 setigers, most intense on prostomium and anterior peristomium. Thoracic region inflated, not depressed, with 10 setigers, wider than abdominal segments. Prostomium short, conical, rounded or blunted on tip, not acute (Fig. 11 A); two nuchal slits sometimes apparent in dorsolateral locations; without eyespots. Peristomium a single achaetous ring, tapering anteriorly, about one-fourth longer than first setiger (Fig. 11 A). Thoracic parapodia similar, inconspicuous, with short postsetal lobes with rounded tips increasing in size along thorax (Fig. 11 A); notopodial lobes elongated, oval-shaped; neuropodial lobes more triangular, but with rounded, not pointed tips (Fig. 11 B). Abdominal notopodial postsetal lobes short, blunt slightly asymmetrical in anterior segments (Fig. 11 C), becoming longer, more symmetrical, somewhat triangular posteriorly (Fig. 11 D); neuropodia short, rounded, expanded without obvious notch; subpodial flange weakly developed in anterior abdominal setigers (Fig. 11 C), becoming larger, blister-like in far posterior setigers. Branchiae from setiger 11 (rarely 12), short, strap-like at first; becoming wide at base, smoothly tapering to rounded tip (Fig. 11 C – D); far posterior branchiae about twice the length of notopodia. Thoracic notosetae arranged in single spreading fascicle of two rows, with setae of anterior row shorter and thinner; neurosetae arranged in two fascicles dorsal and ventral to postsetal lobe. Abdominal notosetae including crenulated capillaries and 0 – 3 furcate setae; furcate setae with unequal tynes connected by row of fine needles (Fig. 11 E). Abdominal neurosetae thin, weakly crenulated. Pygidium a simple ring, lacking cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060E0911FF31FE14FB85F874.taxon	discussion	Remarks. Leitoscoloplos mawsoni was redescribed by Mackie (1987) and is similar to L. geminus in having up to 10 thoracic setigers and branchiae from setiger 11 – 12. The two species are difficult to separate and differentiated mostly on soft parts that may be affected by preservation. The branchiae of L. mawsoni are initially short and straplike, narrow basally, becoming wider basally further posterior and not appearing asymmetrical. In contrast, the branchiae of L. geminus are short and wide at the base from the first and triangular in shape, becoming larger and distinctly asymmetrical in posterior setigers, bending medially. The posterior neuropodial lobes of L. geminus are more distinctly notched than in L. mawsoni; the former has a more conspicuous subpodial flange with a notch separating it from the neuropodium; the flange of L. mawsoni is poorly developed, but both species develop enlarged blister-like flanges in posterior setigers.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060E0911FF31FE14FB85F874.taxon	biology_ecology	Biology. As is typical for Southern Ocean orbiniids, little is known concerning the biology of L. mawsoni. However, collections from the Australian Antarctic program from December 2005 had two obvious size classes: (1) large mature adults with ripe gametes and (2) small juveniles. Many specimens from Dec. 2005 were packed with eggs with average diameters of 215 µm.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060E0911FF31FE14FB85F874.taxon	distribution	Distribution. Southern Ocean: Adelie Land, Wilkes Land and Ross Sea; 3 – 25 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06080912FF31FF7CFD46FB27.taxon	materials_examined	Material examined. Ross Island, McMurdo Sound, off McMurdo Station, 77 ° 51.067 ′ S, 66 ° 39.880 ′ E, 20 m, in sand and silt, coll. S. Kim and J. A. Blake, 11 Jan 2000, (11, LACM-AHF Poly 8957); same location, 30 m, in sponge mat, coll. S. Kim and J. A. Blake, 15 Jan 2000 (3, LACM-AHF Poly 8958). — Antarctic Peninsula, Hero Sta. 1120, 25 – 31 m (45, USNM 187514); Gamma Island, Staten Island Sta. 32 - 63, coll. W. L. Schmitt, 100 m (1, USNM 46389); Anvers Island, Staten Island Sta. 67 - 63, coll. W. L. Schmitt, 62 m (5, USNM 46390). — South Shetland Islands, Hero Sta. 721 - 726 (2, USNM 60170); Sta. 721 - 742 (6, USNM 60169); Sta. 721 - 752 (3, USNM 60173); Sta. 721 - 819 (2, USNM 60171); Sta. 721 - 965 (2, USNM 60165); Sta. 721 - 968 (1, USNM 60159); Sta. 721 - 972 (2, USNM 60158); Sta. 721 - 975 (3, USNM 60160); Sta. 721 - 979 (1, USNM 60161); Sta. 721 - 980 (2 USNM 60168); 721 - 981 (1, USNM 60163); Sta. 721 - 983 (7, USNM 60162); Sta. 721 - 1033 (1, USNM 60164). — Bransfield Strait, Eltanin Sta. 12 - 1003, 210 – 220 m (1, USNM 56522).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06080912FF31FF7CFD46FB27.taxon	description	Description. A moderate-sized species, up to 28 mm long, 1.5 mm wide for about 85 setigers; average size 25 mm long, 1.2 mm wide for about 65 setigers. Color in alcohol: light tan; color in life: yellow to orange, with light brown pigment around mouth opening (based on personal observations at McMurdo Station, 19 Jan 2000). Thoracic region inflated, not depressed, with 10 setigers (7 – 9 in juveniles), wider than abdominal segments (Figs. 12 A, 13 A); transition from thorax to abdomen abrupt (Figs. 12 A, 13 A). Prostomium short, narrow, conical, blunted on tip, not acute (Figs. 12 A, 13 A – B); two nuchal slits in dorsolateral locations (Fig. 13 B) without eyespots. Peristomium a single achaetous ring, at least twice as wide as long, longer than setiger 1 (Fig. 12 A). Thoracic parapodia similar, inconspicuous, with basal cushion from which setae arise; with triangular-shaped notopodial postsetal lobes and more oval-shaped neuropodial postsetal lobes increasing in size along thorax (Fig. 12 B). Abdominal notopodial postsetal lobes wide basally, tapering to elongate narrow tip (Figs. 12 C – D, 13 C). Neuropodia short, rounded, expanded apically, with small notch from which setae arise; small subpodial flange present ventral to neuropodium, separated by a notch (Fig. 12 C); in more posterior setigers, a large, blister-like subpodial swelling usually present ventral to neuropodium (Fig. 12 D). Branchiae from setiger 11 – 12 (10 in juveniles), usually 11, very short, inconspicuous; branchiae short, triangular at first (Fig. 12 C), becoming asymmetrical and irregular in shape in posterior segments (Fig. 12 D), usually bending medially. Thoracic setae crenulated capillaries; notosetae arising from single spreading fascicle consisting of two rows, with shortest and thinnest setae in anterior row; neurosetae arising from two fascicles more or less dorsal and ventral to postsetal lobe (Fig. 12 B); setae of upper fascicle often with dark bases. Abdominal notosetae including crenulated capillaries and 0 – 2 furcate setae; furcate setae with unequal tynes connected by row of very fine needles as interpreted in light microscopy (Fig. 12 E); with SEM, individual needles appearing thicker and fewer; tynes with apical openings (Fig. 13 E). Anterior abdominal neurosetae long, stiff, becoming thinner, posteriorly. Pygidium a simple ring, lacking cirri (Fig. 13 D).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06080912FF31FF7CFD46FB27.taxon	discussion	Remarks. See comparative remarks under Leitoscoloplos mawsoni.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06080912FF31FF7CFD46FB27.taxon	distribution	Distribution. Widespread in shallow Antarctic seas: Ross Sea, McMurdo Sound; South Orkneys, Antarctic Peninsula; South Shetland Islands; 20 – 220 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060A092CFF31FAD7FD0BFDFC.taxon	materials_examined	Material examined. Antarctic Peninsula, Eltanin Station 6 - 439, 0 9 Jan 1963, 63.83 ° S, 62.60 ° W, 128 – 165 m, holotype and 3 paratypes, USNM 1407121 – 2).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060A092CFF31FAD7FD0BFDFC.taxon	description	Description. All specimens posteriorly incomplete; holotype 8.7 mm long, 0.6 mm wide, for 37 segments; largest paratype 8.3 mm long, 0.35 mm wide for 33 segments. Body rounded in cross section, with thoracic region slightly inflated. Thorax with 9 – 10 setigers, with each segment wider than long (Fig. 14 A – B). Transition from thorax abrupt, denoted by reduction in number of neurosetae and change in form of neuropodial postsetal lobes. Abdominal segments narrow at first, then becoming elongate, nearly twice as long as wide with parapodia at posterior end of each elongated segment (Fig. 14 C). Color in alcohol: brown. Prostomium elongate, more than twice as long as wide; tapering anteriorly to narrow, rounded tip, sometimes curved dorsally; eyespots absent; with paired nuchal organs. Peristomium short asetigerous ring, together with prostomium forming unusually elongate “ head ” (Fig. 14 A – B) Thoracic notopodia short, papillate on setiger 1 and sometimes setiger 2, then becoming long, fingerlike over remaining thoracic setigers; abdominal notopodia elongate, becoming narrow more posteriorly (Fig. 14 C – D). Thoracic neuropodia similar to notopodial lamellae, but overall shorter and more triangular. Abdominal neuropodia, short, thickened basally, notched distally; with subpodial flange (Fig. 14 D). Thoracic setae all long crenulated capillaries. Abdominal notopodia with 6 – 8 crenulated capillaries and 1 – 2 furcate setae; furcate setae with thin needles forming web between subequal tynes; barbs on shaft not apparent in light microscopy (Fig. 14 E). Abdominal neuropodia with 2 – 3 thin, non-crenulated capillaries (Fig. 14 D). Branchiae from setiger 13 – 14, continuing to end of fragment; each branchia short, narrowing to rounded apex, barely longer than notopodial lobes in thoracic segments, shorter in abdominal segments (Fig. 14 D). Pygidium unknown.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060A092CFF31FAD7FD0BFDFC.taxon	etymology	Etymology. The epithet is derived from the Latin nasus (m), for nose, to denote the usually elongate and narrow prostomium-peristomium that characterizes this species.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060A092CFF31FAD7FD0BFDFC.taxon	discussion	Remarks. Leitoscoloplos nasus n. sp. is another Antarctic species in the L. kerguelensis group with a reduced number of thoracic setigers and branchiae from anterior abdominal segments. The species is easily recognized and distinguished from other species of the genus in Antarctica and elsewhere by the elongate and unusually narrow “ head ” consisting of the prostomium-peristomium, and by the long, narrow abdominal segments. Leitoscoloplos drakei described below also has elongate abdominal segments, but this species is thin and threadlike with branchiae limited to far posterior segments.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD060A092CFF31FAD7FD0BFDFC.taxon	distribution	Distribution. Antarctic Peninsula, 128 – 165 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0634092FFF31FD64FCD4FCBF.taxon	materials_examined	Material examined. South Atlantic Ocean, South Georgia Island, N of Shag Rocks, Eltanin Sta. 22 - 1527, 0 9 Jan 1963, 63.83 ° S, 62.60 ° W, 3742 – 3806 m, holotype and 3 paratypes (USNM 69403 – 4).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0634092FFF31FD64FCD4FCBF.taxon	description	Description. All specimens posteriorly incomplete; holotype 16 mm long and 2 mm wide for 40 segments; paratypes of similar size. Color in alcohol: brown with darker pigment markings on prostomium and some anterior segments. Body rounded in cross section, with thoracic region slightly depressed; one paratype with mid-ventral line of body inverted, forming long groove. Transition from thorax abrupt, denoted by reduction in number of neurosetae and change in form of neuropodial postsetal lobes. Prostomium conical, pointed anteriorly (Fig. 15 A); without distinct eyespots, but with several groups of small pigment spots (Fig. 15 B). Peristomium formed of single tapering achaetous ring. Thorax with 10 setigers (Fig. 15 A). Notopodia of setigers 1 – 3 inconspicuous, with short triangular-shaped digitiform postsetal lobes from setiger 4 (Fig. 15 C), becoming bilobed in abdominal setigers, with ventral lobes shorter than dorsal (Fig. 15 D). Thoracic neuropodia with tapering digitiform postsetal lobes (Fig. 15 C); abdominal neuropodia becoming apically thicker and more erect (Fig. 15 D). Thoracic setae all long crenulated capillaries. Abdominal notopodia with crenulated capillaries and 3 – 4 furcate setae; furcate setae with thin needles forming web between subequal tynes; with rows of short barbs on shaft (Fig. 15 E). Abdominal neuropodia with 3 – 4 thin, non-crenulated capillaries and 2 – 3 imbedded simple aciculae. Branchiae from setiger 20, continuing to end of fragment; each branchia short, stubby, barely longer than notopodial lobes (Fig. 15 D). Pygidium unknown. Holotype and one paratype with large, irregularly shaped ova, measuring 450 – 500 µm in largest dimension.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0634092FFF31FD64FCD4FCBF.taxon	etymology	Etymology. This species is named for the USNS Eltanin, former research vessel of the United States Antarctic Research Program.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0634092FFF31FD64FCD4FCBF.taxon	discussion	Remarks. Leitoscoloplos eltaninae n. sp. is a deep-sea species that belongs to the L. kerguelensis group in having branchiae first present from anterior abdominal segments. It is closest to L. rankini n. sp., described below, in having a thorax with 10 setigers and branchiae from similar setigers (setiger 18 in L. rankini n. sp.; setiger 20 in L. eltaninae n. sp.). The two species differ in that L. eltaninae n. sp. has bilobed abdominal notopodia and entire neuropodia, whereas L. rankini n. sp. has undivided, fingerlike abdominal notopodia and bilobed neuropodia. In L. eltaninae n. sp. the branchiae are short and stubby, while in L. rankini n. sp. the branchiae are long and thin.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0634092FFF31FD64FCD4FCBF.taxon	distribution	Distribution. South Atlantic Ocean, 3742 – 3806 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0637092FFF31FC22FD4DF82E.taxon	materials_examined	Material examined. Antarctic Peninsula, Anvers Island, Arthur Harbor, Hero Inlet, Glacier Sta. 68 - Palmer II, 17 Mar 1968, 64.77 ° S, 64.07 ° W, 40 m, holotype (USNM 61943).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0637092FFF31FC22FD4DF82E.taxon	description	Description. Holotype complete, broken into three parts, totaling 20 mm long and 1.2 mm wide for 56 setigerous segments. Color in alcohol: light tan. Thoracic region slightly flattened dorsoventrally; abdominal region cylindrical; middle abdominal segments moniliform. Prostomium reduced, short, triangular, wider than long, weakly pointed anteriorly, smoothly rounded on anterior margin, recessed into large peristomial segment; nuchal organs not observed; no eyespots (Fig. 16 A). Peristomium superficially divided into one large and one small achaetous ring; distinct from setiger 1. Thorax with eight setigers, all similar. Notopodia with thin, cirriform postsetal lobes throughout body (Fig. 16 C – D); thoracic neuropodia simple, with elliptical postsetal lobes (Fig. 16 C); neuropodia of middle and posterior segments dorsoventrally swollen, forming weakly developed ventral flange, surmounted by short, triangular postsetal lobe (Fig. 16 E). All thoracic setae arranged in irregular fascicles of 25 – 30 crenulated capillaries (Fig. 16 C). Abdominal neurosetae including 2 – 3 simple, non-crenulated capillaries and 2 – 3 imbedded aciculae. Abdominal notosetae including 3 – 5 long, crenulated capillaries and 1 – 2 furcate setae; furcate setae with three thin needles connected to blunted subequal tynes by a thin membrane (Fig. 16 F). Branchiae from setiger 17; small, stubby at first (Fig. 16 D), increasing in size over subsequent setigers, becoming greatly enlarged; middle and posterior setigers with enlarged, flattened, membranous branchiae with thick inner and outer gland-like supportive structures and thin membranous blade with venation (Fig. 16 E). Pygidium with two lobes lacking cirri (Fig. 16 B).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0637092FFF31FC22FD4DF82E.taxon	etymology	Etymology. The epithet, phyllobranchus, is derived from the Greek phyllon for leaf; branchos for gill. The name is suggested by the thin membranous appearance of the branchiae.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0637092FFF31FC22FD4DF82E.taxon	discussion	Remarks. Leitoscoloplos phyllobranchus n. sp. is a unique species in the form of the thin, membranous branchiae that start from setiger 17.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0637092FFF31FC22FD4DF82E.taxon	distribution	Distribution. Antarctic Peninsula, 40 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0636092BFF31F8AEFCA2FA5C.taxon	description	Haploscoloplos sp. Hartman 1978: 156 (in part, Glacier Sta. 69 - 19).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0636092BFF31F8AEFCA2FA5C.taxon	materials_examined	Material examined. Drake Passage, ANDEEP I ANT XIX- 3, R / V Polarstern, Sta. PS- 61 / 43 - 2, 3959 m (1, SEM, JAB); Sta. PS- 61 / 46 - 3, 2888 m (1, ZMH P- 27799). — Weddell Sea, Glacier Sta. 69 - 19, 11 Mar 1969, 74.105 ° S, 32.603 ° W, 1622 m, holotype (USNM 1013903); ANDEEP III ANT XXII- 3, R / V Polarstern, Sta. PS- 67 / 121 - 6, 2618 m (1, ZMH P- 27800).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0636092BFF31F8AEFCA2FA5C.taxon	description	Description. Holotype posteriorly incomplete, broken into three parts, 22 mm long, 1 mm wide for 50 setigerous segments; 10 thoracic setigers. Specimen from Sta. PS- 61, 46 - 3 complete, 19 mm long, 0.8 mm wide for 80 setigers; with 11 thoracic setigers. Specimen from Sta. PS- 67, 110 - 11 smaller, complete, in two parts, 7 mm long, 0.4 mm wide for 40 setigers; with 9 thoracic setigers. Thoracic region widest part of body, with 9 – 11 setigers, rounded in cross section, not depressed (Fig. 17 B). Transition between thorax and abdomen abrupt (Fig. 17 A) or with one transitional segment. Abdominal segments becoming narrow in posterior one-third of body. Branchiae from setiger 18 – 21, small and stubby at first, becoming thin, about twice as long as notopodial postsetal lobes (Fig. 17 C). Prostomium conical, pointed; no eyespots (Figs. 17 A, 18 A); nuchal organs as large slit between prostomium and peristomium (Fig. 18 B). Peristomium with one achaetous ring (Figs. 17 A, 18 A). Thoracic segments all similar, with prominent postsetal lobes; notopodial postsetal lobes subtriangular (Fig. 17 B); neuropodial postsetal lobe arising from low postsetal ridge (Fig. 17 B). Middle and posterior abdominal parapodia dorsally elevated; elevated parapodia fused across dorsum, forming raised dorsal crest from which branchiae arise, best observed in posterior abdominal segments (Fig. 18 C). Abdominal notopodia with narrow fingerlike postsetal lobe (Figs. 17 C, 18 D); neuropodia elongated, apically expanded, divided into two lobes between which setae arise (Fig. 17 C); without subpodial flange. Branchiae short at first (Fig. 18 C – D), then becoming longer than notopodial lobes in far posterior segments (Fig. 17 C). Thoracic setae all crenulated capillaries (Fig. 18 E); notopodial fascicles with 6 – 8 setae; neurosetae more numerous, arranged in two dense rows. Abdominal notopodia with 6 – 9 long capillaries and 3 – 4 furcate setae; each furcate seta with one tyne shorter than the other, both blunted on tips with apical notch; tynes connected by thin webbing composed of fine needles (Fig. 17 D). Abdominal neuropodia with long and short capillaries; 1 – 2 very short and thin aciculae, sometimes protruding. Pygidium with two thin cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0636092BFF31F8AEFCA2FA5C.taxon	etymology	Etymology. This species is named for the late Dr. John S. (Stubby) Rankin, Professor Emeritus of the University of Connecticut, friend, and teacher. Dr. Rankin was director of the sampling program during the International Weddell Sea Expedition (1968 – 69).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0636092BFF31F8AEFCA2FA5C.taxon	discussion	Remarks. Leitoscoloplos rankini n. sp. is a deep-sea species belonging to the L. kerguelensis group in having branchiae first present from the anterior abdominal region. The species differs from related forms in the nature of the inflated and elevated parapodia of the posterior abdominal segments. These parapodia are located on the posterior border of the segments and are elevated dorsally to form prominent crests. Further differences with related forms are discussed under L. eltaninae n. sp. (see above).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0636092BFF31F8AEFCA2FA5C.taxon	distribution	Distribution. Drake Passage and Weddell Sea, 1622 – 3959 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06330927FF31FA04FA89FBCF.taxon	materials_examined	Material examined. Drake Passage, Eltanin Sta. 4 - 145, 11 Aug 1962, 60.00 ° S, 64.82 ° W, 3312 – 3532 m, holotype and paratype (USNM 55534 – 5). — Drake Passage, ANDEEP I ANT XIX- 3, R / V Polarstern, Sta. PS- 61 / 043 - 2, 3958 m (1, ZMH P- 27789); PS- 61 / 114 - 6, 2905 m, (1, ZMH P- 27790). — Weddell Sea, Glacier Sta. 68 - 18, 1664 m (20, USNM 46602); Sta. 68 - 55, 2936 m (3, USNM 46603); Sta. 69 - 19, 1622 m (3, USNM 46608); Sta. 69 - 21, 2288 m (3, USNM 46609); Sta. 69 - 27, 4575 m (1, USNM 46610). — Weddell Sea, ANDEEP II ANT XIX / 4, R / V Polarstern, Sta. PS- 61 / 131 - 8, 3068 m, (1, ZMH P- 27791); PS- 61 / 132 - 4, 2085 m (2, ZMH P- 27792); (1, SEM, JAB); Sta. PS- 61 / 132 - 6, 2086 m (1, ZMH P- 27793); Sta. PS- 61 / 136 - 5, 4 741 m (1, ZMH P- 27794); Sta. PS- 61 / 138 - 7, 4539 m, 4541 m (1, ZMH P- 27795); Sta. PS- 61 / 138 - 8, 4539 m (1, SEM, JAB), Sta. PS- 138 - 9, 4 538 m (2, JAB, photographic records); Sta. PS- 61 / 138 - 10, 4537 m (1, SEM, JAB); ANDEEP III ANT XXII- 3, R / V Polarstern, Sta. PS- 67 / 078 - 8, 2167 m (1 juvenile, JAB); PS- 67 / 102 - 8, 4803 m (1, ZMH P- 27798); Sta. PS- 67 / 142 - 7, 3406 m (1, ZMH P- 27797). — South African Basin, ANDEEP III Sta. PS- 67 / 021 - 3, 4551 m (1, ZMH P- 27796).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06330927FF31FA04FA89FBCF.taxon	description	Description. Body thin, threadlike, fragile, largest complete Weddell Sea specimens 15 mm long, 0.35 – 0.5 mm wide for 36 setigerous segments; type specimens from Drake Passage shorter, due to absence of most of abdominal region. Color in life (ANDEEP I – II specimens) iridescent blue cuticle on transparent body (Fig 21 A); in alcohol opaque white to light tan. Thoracic region with 8 – 9 short, annulated setigers, with last segment sometimes longer, transitional (Figs. 19 A, 20 B); thoracic region followed by long abdominal region composed of distinctly elongated segments with parapodia located on elevated ridge on posterior border of each segment (Figs. 19 B – C, 20 C); anterior and middle abdominal segments up to 2.5 x longer than wide; far posterior segments over 7 x longer than wide (Figs. 19 D, 21 B); fragile nature of far posterior segments probably accounting for lack of complete specimens in preserved samples. Demarcation between thorax and abdomen also identified by a reduced number of neurosetae and elongation of neuropodial lobes. Prostomium narrowing anteriorly, conical in shape (Figs. 20 A – B, 21 A – C) sometimes appearing pointed (Fig. 19 A); appearing dorsoventrally flattened with SEM in lateral view (Fig. 20 B); eyespots and nuchal organs not observed in light microscopy; nuchal organs observed in SEM (Fig. 20 B, inset); peristomium swollen, sometimes elongate and fused with setiger 1 (Fig. 20 A), weakly divided into two separate annulations (Figs. 19 A, 20 B), or not. Thoracic parapodial lobes short, stubby, indistinct (Figs. 19 A, 20 B); notopodia becoming elongated and cirriform in anterior abdominal setigers (Fig. 19 B), then becoming narrower and more fingerlike in posterior setigers (Fig. 19 C – D). Abdominal neuropodia thickened, apically expanded (Figs. 19 B – D, 20 C). Thoracic noto- and neurosetae thin crenulated capillaries. Abdominal notosetae including 6 – 8 capillaries, furcate setae absent; abdominal neurosetae including 1 – 2 long capillaries; acicula imbedded, rarely with tip emergent. Branchiae from setiger 18 – 20 (Fig. 19 C); branchial region missing from type specimens. Pygidium with two thin anal cirri (Figs. 19 E – F, 21 B). Description of juvenile. A complete juvenile believed to belong to this species was found in a sample from the Weddell Sea (Sta. PS- 67 / 078 - 8) as part of the ANDEEP III Program on the RV Polarstern. Specimen complete, consisting of 18 setigerous segments 1.24 mm long and 0.15 mm wide (Fig. 19 F). Thorax with seven setigerous segments; separation between thoracic segments and abdomen abrupt. All thoracic segments narrow, wider than long; first two abdominal segments longer, with setiger 8 about as long as wide; following abdominal segments narrow, wider than long. Thoracic noto- and neuropodia with simple fingerlike postsetal lamellae; abdominal notopodia also with simple postsetal lamellae; abdominal neuropodia expanded into inflated glandular lobe bearing weakly notched tip. Thoracic noto- and neurosetae all camerated capillaries; abdominal notosetae also camerated capillaries; abdominal neurosetae simple, smooth capillaries, some minute, hairlike. Branchiae not developed on this juvenile. Pygidium with two lobes surrounding anus; with two long, thin anal cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06330927FF31FA04FA89FBCF.taxon	discussion	Remarks. Leitoscoloplos drakei is a small, fragile deep-sea species that was depicted by Hartman (1967: pl. 34) as having two distinct asetigerous segments preceding the first setiger and with branchiae absent, resulting in her referring the species to the genus Orbiniella. The illustrated specimen was the paratype. The peristomial region of that specimen, upon subsequent examination, was found to have only a single asetigerous segment. The entire peristomial area is swollen and stretched on all specimens and distinct segmental boundaries are not clear, although extra grooves may be apparent providing an appearance of an extra asetigerous segment, but this is variable. Since this species has branchiae and the abdominal parapodia are elevated and modified, it belongs to the subfamily Orbiniinae instead of Microrbiniinae and is here reassigned to the genus Leitoscoloplos. Branchiae are lacking on the type specimens. The Weddell Sea specimens, however, are more complete, with most retaining all or part of their abdominal region. In life, complete specimens are very fragile, with posterior abdominal segments at least 7 x as long as wide. It is unlikely that such specimens would often remain intact in preservation with the typical benthic sieving procedures. However, on the ANDEEP I – II cruises, an elutriation device was used where the organisms were floated out of the sediment on to a 63 µm sieve. These specimens were subsequently set up in Petri dishes in a refrigerator for later examination in life. On those specimens the body in life by reflected light was observed to be of an iridescent blue color (Fig. 21 A). Branchiae were clearly present by at least setiger 20. Further, it was possible to observe the pygidium and two thin anal cirri (Fig. 21 B). Leitoscoloplos drakei differs from other species in the nature of the elongated segments, the overall threadlike appearance of the body, and lack of furcate setae.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06330927FF31FA04FA89FBCF.taxon	distribution	Distribution. Drake Passage, 3312 – 3532 m; Weddell Sea, 1622 – 4575 m; South African Basin, 4551 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063F0926FF31FB8DFC13FE10.taxon	materials_examined	Type species: Lumbricus armiger Müller, 1776, by monotypy. Synonym: Scolaricia Eisig, 1914. Type-species: Scolaricia typicus Eisig, 1914, by monotypy. Fide Day 1973.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063F0926FF31FB8DFC13FE10.taxon	diagnosis	Diagnosis. Prostomium pointed, usually prolonged; single achaetous peristomial ring. Branchiae first present from middle or posterior thoracic setigers or from abdominal setigers (8 – 26). Posterior thoracic setigers with 0 – 2 postsetal lobes and 0 – 2 subpodial lobes, never more than four lobes of both types combined; not forming ventral fringes. Thoracic neurosetae including blunt, inconspicuous uncini, few in number, not in distinct rows, and accompanied by numerous crenulated capillaries; furcate setae usually present; heavy spear-like spines and bristletopped setae absent. Abdominal neuropodia with embedded, non-projecting acicula. Abdominal noto- and or neuropodial flail setae present or absent.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063F0926FF31FB8DFC13FE10.taxon	discussion	Remarks. The definition of Scoloplos is here emended and restricted to species having only inconspicuous spines in thoracic neuropodia accompanied with numerous capillaries, and branchiae from setiger 8 – 26. Leodamas, usually treated as a subgenus of Scoloplos, was raised to full generic status by Blake (2000). The latter genus has large, conspicuous spines in thoracic neuropodia, with few or no accompanying capillaries, and branchiae usually from setigers 4 – 6, however, another group of species has branchiae from posterior thoracic or anterior abdominal setigers. Another, but less reliable distinction between the two genera is that the abdominal neuropodial aciculae tend to be small and imbedded in Scoloplos species and larger and projecting in Leodamas species. Pettibone (1957) distinguished between Scoloplos and Leodamas in a different manner. Scoloplos species were said to have a papilla in the middle of the thoracic neuropodial lobes, while Leodamas species lacked these papillae. While many species of Leodamas do have low, rounded postsetal lobes and lack papillae or cirriform lobes throughout much of the thoracic region, most species develop prolonged postsetal lobes in posterior thoracic setigers. According to Hartman (1948), the thoracic neuropodial postsetal lobes of Leodamas verax Kinberg, the type-species of Leodamas, are triangular and undivided. This structure has been confirmed in the present study. Thus, the presence of a prolonged postsetal lobe on the thoracic neuropodium of the type-species of Leodamas would appear to preclude its use as a definitive character for Scoloplos sensu stricto. The genus Scolaricia was originally distinguished from Scoloplos on the basis of having flail setae in abdominal neuropodia (Eisig, 1914). However, these setae have now been found in several genera and since the character is homoplasic within the Orbiniidae and not unique to Scolaricia, the genus was referred to synonymy with Scoloplos by Day (1973). In the present study, two previously undescribed species of Scoloplos were encountered: S. bathytatus, n. sp., and S. suroestense, n. sp. Another species, S. armiger, the type species, has been reported from South America (Ehlers, 1901; Rozbaczylo, 1985), but was not found in the present study.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063E0923FF31FDCFFE34FE0F.taxon	materials_examined	Material examined. Drake Passage, Eltanin Sta. 6 - 384, 25 Dec 1962, 57.03 ° S, 56.47 ° W, 3138 – 3426 m, 1 paratype (USNM 60685); R / V Polarstern, ANDEEP I, Sta. PS- 61 / 042 - 6, 3692 m. 28 Jan 2002, box core, (1, ZMH P- 27783); Sta. PS- 61 / 046 - 3, 2888 m, (1, ZMH P- 27784); Sta. PS- 61 / 046 - 5, 30 Jan 2002, 2893.6 m, box core (1, ZMH P- 27785); Sta. PS- 61 / 114 - 6, 2905 m (1, ZMH P- 27786); Sta. PS- 61 / 114 - 8, 2905 m (1, ZMH P- 27787; 1, SEM, JAB). — near South Orkney Islands, Eltanin Sta. 7 - 480, 15 Feb 1963, 58.13 ° S, 44.85 ° W, 2800 m, 2 paratypes (USNM 56464). — near South Georgia, Eltanin Sta. 9 - 720, 7 Sep 1963, 56.10 ° S, 34.02 ° W, 2828 – 2873 m, holotype (USNM 60684). — Weddell Sea, Glacier Sta. 69 - 22, 3111 m (3, USNM 46611); Glacier Sta. 68 - 1, 13 Mar 1969, 73 ° 28.4 ′ S, 30 ° 26.9 ′ W, 650 m (8 paratypes, USNM 1013915); R / V Polarstern, ANDEEP III ANT XXII- 3, R / V Polarstern, Sta. PS- 67 / 078 - 4, 2164 m (1, ZMH P- 27788); Sta. PS- 67 / 121 - 12, 2657 m (1, SEM, JAB); Sta. PS- 67 / 153 - 4, 2079 m (1, SEM, JAB).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063E0923FF31FDCFFE34FE0F.taxon	description	Description. A small species, mostly represented by posteriorly incomplete specimens; holotype 4 mm long, 0.5 mm wide for 20 setigers; paratype (USNM 60685) 7.5 mm long, 0.5 mm wide for 29 setigers; specimen from (ZMH P- 27788) larger, complete in two parts, 13 mm long for about 57 setigers. Color in alcohol: light tan. Body cylindrical throughout; thoracic region with 11 – 12 setigerous segments; peristomium and first 3 – 4 setigers swollen, partially inflated, with segmental boundaries somewhat obscured (Figs. 22 A, 23 A – B); subsequent segments smooth, distinct from one another, with prominent dorsal intersegmental annulations apparent from between setigers 4 and 5; each annulation with medial swollen area, sometimes bearing black reticulated pigment (Figs. 22 A, 23 A – B); ventral annulations apparent from setigers 13 – 14. Prostomium elongated, pointed on anterior margin (Figs. 22 A, 23 A – B); no eyespots; nuchal slits observed with SEM (Fig. 23 B – C); peristomium with one simple achaetous ring. Setigers 1 – 2 lacking parapodial appendages, but with well-developed setal fascicles. Notopodia with minute postsetal lamellae from setiger 3 (Fig. 22 A), becoming longer, cirriform over subsequent segments (Fig. 22 B); thoracic neuropodia dorsoventrally elongated, with postsetal lamellae present from setiger 3 – 4 (Fig. 22 B); initially lamellae fingerlike, becoming triangular near end of thoracic region (Fig. 22 B); abdominal notopodia, elongate, fingerlike as in thoracic segments (Fig. 23 E); abdominal neuropodia elongated, flattened, expanded apically, with short ventral cirrus (Fig. 23 E); interramal cirri absent. Branchiae from setiger 9 – 10, continuing to end of fragments; each branchia broad basally, somewhat flattened (Figs. 22 A, 23 E). Thoracic notopodia with fascicles of crenulated capillaries (Fig. 22 E); with those of setigers 2 – 5 unusually long (Fig. 22 A); abdominal notopodia with 2 – 3 non-crenulated, smooth capillaries and 3 – 4 furcate setae (Fig. 22 C). In light microscopy, furcate setae appearing to have a web between two unequal tynes (Fig. 22 C); in SEM furcate setae observed with a curved array of 8 – 9 teeth, fused basally, and partly free at tips connecting and fused to tynes; both tynes with a distinct apical opening (Fig. 23 F). Thoracic neurosetae with 1 – 2 rows of uncini (Fig. 22 D) and 2 – 3 rows of long crenulated capillaries (Fig. 22 E); uncini blunt tipped, curved, bearing distinct ribs (Figs. 22 D, 23 D); abdominal neuropodia with 2 – 3 embedded or partially protruding aciculae. Posterior end with two dorsolateral anal cirri (ZMH P- 27788). A juvenile from ANDEEP I Sta. PS- 61, 046 - 5 (ZMH P- 2785), 1.5 mm long, and with same expanded thorax and long capillary notosetae found in adults. Thorax with nine setigers, branchiae from setiger 8. Noto- and neuropodia first evident from setiger 3. Fascicles of thoracic noto- and neurosetae fewer than in adults, arranged in no more than two rows; 2 – 3 neuropodial uncini per fascicle, only found on setigers 3 – 5, these with distinct ribs along shaft forming shelves along one side, with tip of uncini surrounded by partial hyaline hood on shortest emerging setae; crenulated capillaries with individual facets rib-like, each with finely barbed or serrated border. Abdominal notopodia with narrow, fingerlike lamella, slightly enlarged and rounded apically; abdominal neuropodia expanded, with short ventral cirrus. Abdominal notosetae including 1 – 2 furcate setae and 3 – 4 long, minutely serrated capillaries; abdominal neurosetae smooth capillaries or with minute, barely discernible barbs.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063E0923FF31FDCFFE34FE0F.taxon	etymology	Etymology. Bathytatus, Greek for deepest.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063E0923FF31FDCFFE34FE0F.taxon	discussion	Remarks. Scoloplos bathytatus n. sp. is a small deep-sea species that differs from related forms in having a cylindrical body throughout, and unusually long capillary notosetae in anterior setigers. The intersegmental annulations are especially prominent in this species, as is the swollen and elongated anterior end. The closest relative to S. bathytatus n. sp. appears to be S. ehlersi Blake, 1985, described from sediments near deep-sea hydrothermal vents at the Galápagos Rift off Ecuador. S. ehlersi superficially resembles S. bathytatus n. sp. in size and form, but differs significantly in having branchiae from setiger 21, an anterior abdominal segment, instead of setigers 9 – 10 (Blake 1985).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063E0923FF31FDCFFE34FE0F.taxon	distribution	Distribution. Off South America, in subantarctic areas from the Drake Passage to South Georgia, 2800 – 3463 m; Weddell Sea, 650 – 3111 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063B0923FF31FDCFFCE5F853.taxon	materials_examined	Material examined. Juan Fernandez Islands, Chile Bay behind Punta Suroestense, Anton Bruun Cruise 12, Sta. 134, 13 Dec 1965, 33 ° 34 ′ S, 78 ° 55 ′ W, shallow subtidal (<5 m), holotype and 3 paratypes (USNM 1013917 – 8).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063B0923FF31FDCFFCE5F853.taxon	description	Description. Holotype complete, 12 mm long and 1.2 mm wide for approximately 100 segments; paratypes smaller, up to 75 segments. First four thoracic segments distinctly inflated, due to inverted proboscis visible dorsally through body wall (Figs. 23 G, 24 A – B); following thoracic segments distinctly depressed (Figs. 23 A, 24 B – C); abdominal segments rounded in cross section (Fig. 24 D). Thorax with 10 – 15 setigers, depending upon size of specimens; smallest specimens with fewest thoracic segments, larger specimens with most thoracic segments; last 1 – 2 thoracic segments appearing transitional with abdominal region in having fewer, more tightly grouped setae. Color in alcohol: light tan. Prostomium triangular, pointed anteriorly (Figs. 23 G, 24 A – B); no eyespots; with two ciliated dorsolateral nuchal organs on posterior border with peristomium of holotype (Fig. 24 A); with SEM, nuchal organ of paratype a slit (Fig. 23 A). Peristomium with a single achaetous ring completely fused to setiger 1. Thoracic parapodia with digitiform postsetal lobes from setiger 1 (Fig. 24 A – B); neuropodial lobes slightly shorter than notopodial lobes. Anterior abdominal postsetal lobes similar to those of thoracic region, with neuropodial lobes becoming reduced to short papillae in middle body segments; notopodial lobes remaining long, but shorter than branchiae (Fig. 24 D). No interramal or subpodial lobes present. Notosetae all crenulated capillaries throughout; furcate setae entirely absent. Thoracic neurosetae including 8 – 9 uncini located anterior to 12 – 14 crenulated capillaries (Figs. 23 H, 24 C); uncini slender, no broader than capillaries, with blunted curved tips partially covered by hyaline hood (Fig. 24 E – F), in SEM hood appearing as a sheath extending from tip of shaft posteriorly (Fig. 23 H); shafts with ribs that in light microscope and SEM consist of transverse rows of barbs (Figs. 23 H, 24 E – F), capillaries with transverse rows of barbs (Figs. 23 H, 24 G). Abdominal neurosetae including 2 – 3 straight pointed uncini (Fig. 24 H) and 3 – 4 capillaries. Branchiae from setiger 12 – 17 or first 1 – 2 abdominal segments (Fig. 24 B). Pygidium with terminal anus, encompassed by broad, thickened lobe, without anal cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063B0923FF31FDCFFCE5F853.taxon	discussion	Remarks. Scoloplos suroestense n. sp. is unusual among species of Scoloplos in having branchiae first present from anterior abdominal setigers. In this regard, the species is closely related to S. normalis (Day, 1977) and S. difficilis Day, 1977, both from Australia (Hartman 1957; Day 1977; Mackie 1987). Scoloplos normalis, originally described in the genus Leitoscoloplos by Day (1977), was transferred to Scoloplos by Mackie (1987) after he discovered that the paratypes had a few short, robust and weakly serrated uncini with a close adhering hood among neuropodial capillaries of the first three thoracic setigers; one small specimen had uncini distributed over a greater range of setigers. Scoloplos suroestense n. sp., in contrast, has 8 – 9 uncini and 12 – 14 capillaries in all thoracic neuropodia. Further the uncini of S. suroestense n. sp. have rows of barbs all along the shaft and bear a thin hyaline sheath at the tip. The nature of the thoracic neuropodial uncini on S. suroestense n. sp. also differs from the smooth shafted uncini reported by Day (1977) for S. difficilis.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063B0923FF31FDCFFCE5F853.taxon	etymology	Etymology. The epithet is taken from Punta Suroestense, near the type locality in the Juan Fernandez Islands.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063B0923FF31FDCFFCE5F853.taxon	distribution	Distribution. Juan Fernandez Islands, shallow subtidal.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	Synonym: Branchethus Chamberlin, 1919. Type-species: Branchethus latum Chamberlin, 1919, by monotypy. Fide Hartman 1957.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	diagnosis	Diagnosis. Prostomium pointed on anterior margin, usually prolonged; most species with a single achaetous peristomial segment; immature adults of some species with two achaetous peristomial segments and adults of at least one species with vague indication of two achaetous segments. Branchiae single or multiple branches, either from anterior thoracic setigers 4 – 7 or from posterior thoracic setigers or first abdominal setigers. Posterior thoracic setigers with 0 – 2 postsetal lobes and 0 – 2 subpodial lobes, never more than four lobes of both types combined; not forming ventral fringes. Thoracic neuropodial uncini large, conspicuous arranged in one to many distinct vertical rows, with accompanying capillaries few or entirely lacking; heavy spear-like spines and bristle-topped setae absent. Abdominal neuropodia with projecting aciculae, either thin and inconspicuous or large and curved apically. Abdominal noto- or neuropodial flail setae present or absent.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	etymology	Etymology. The generic name Leodamas Kinberg, 1866, is formed from Leo, Greek for lion, and dama, Latin for deer. It seems likely that Kinberg noticed the branches of the thoracic notopodial lamellae and compared them with antlers of a deer, hence the name. Leo is masculine, dama can be both masculine and feminine, but I believe this genus name is masculine as evidenced by the masculine name of the type species, verax.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	discussion	Remarks. Leodamas was raised to full generic status by Blake (2000). A phylogenetic analysis demonstrated that Leodamas species were more closely related to species of Orbinia, Phylo, and Naineris than to Scoloplos sensu stricto. Previously, Leodamas was regarded as a subgenus of Scoloplos. The chief difference between species of Scoloplos and Leodamas is with the form and arrangement of the thoracic neuropodial uncini. In species of Scoloplos the thoracic neuropodial uncini are relatively thin, inconspicuous, and accompanied in each setal row by numerous capillaries. In contrast, the thoracic neuropodial uncini of all species of Leodamas are large, conspicuous and arranged in 1 – 7 (usually 1 – 4) distinct vertical rows; capillaries if present, are few in number, in separate fascicles, usually dorsal to the uncini, and relatively inconspicuous. One unique feature of several species of Leodamas, including the type-species, L. verax, is that the anterior row of uncini often extends ventrally, curving under other rows of uncini, continuing dorsally as a short posterior row. Other species of Leodamas confirmed to have this feature include L. cirratus, L. cochleatus, L. cylindrifer, L. hyphalos n. sp., L. maciolekae n. sp., L. marginatus, and L. tribulosus. By having such large and heavy thoracic neuropodial uncini, species of Leodamas are more similar to species of Naineris, Orbinia, and Phylo than to Scoloplos. Most species of Leodamas have emergent neuropodial aciculae in abdominal segments. The appearance of branchiae on anterior thoracic setigers in most of the better known species of Leodamas is usually considered as another way to separate these species from Scoloplos where branchiae begin more posteriorly. However, some Leodamas species with rows of heavy thoracic neuropodial uncini do have branchiae first present from a more posterior setiger. In order to better understand the relationships of the South American and Antarctic species of Leodamas encountered as part of this study, species currently assigned to Leodamas either as a full genus or as a subgenus to Scoloplos were reviewed based largely on the literature. This review suggests that species of Leodamas may be divided into two groups (Table 1): (A) Species with branchiae beginning from an anterior thoracic setiger (4 – 7) and with the thoracic neuropodial uncini typically occurring in three or more vertical rows and (B) Species with branchiae beginning from a posterior thoracic or anterior abdominal setiger and with thoracic neuropodial uncini typically occurring in only 1 or 2 vertical rows. In general this dichotomy holds up well, however L. acutissimus (Hartmann-Schröder, 1991) is intermediate with branchiae beginning from a posterior thoracic segment and with 3 – 4 vertical rows of thoracic neuropodial uncini. The following list includes all known species of Leodamas either derived from the literature or encountered in this study. Table 1 includes the main morphological characters as taken from key references or from actual observations. There are likely additional species of Scoloplos that may eventually be reassigned to Leodamas. The following 29 species of Leodamas are currently recognized. Species with branchiae from an anterior thoracic setiger (4 – 7); thoracic neuropodial uncini in 3 – 4 or more vertical rows:	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	As part of this review several potential taxonomic problems have been identified, largely associated with the nature of the abdominal neuropodial uncini, including their size and the degree of curvature of the curved or hooked tip. Leodamas dubius was originally described from West Africa by Tebble (1955). However, the original account was brief and certain key characters were not clearly discussed or illustrated. The species was subsequently reported from Viet Nam (Gallardo 1967), the Andaman Sea (Eibye-Jacobsen 2002), and Australia (Hartmann- Schröder 1979 as L. rubra australiensis fide Eibye-Jacobsen 2002) and Zhadan et al. (2015). The two latter accounts reported considerable variability in the size, shape, and degree of curvature of the abdominal neuropodial uncini. It is likely that the original West African account and the more recent reports from Asia and Australia represent different species. The only resolution to this would be to re-examine the specimens reported by Tebble (1955). Another potential problem involves L. johnstonei which was originally described from southern Africa by Day (1934) and has subsequently been reported from Australia (Day 1977). Here the main issue seems to be with the presence of 1 or 2 subpodial papillae in the last thoracic and anterior abdominal segments. Other aspects of the morphology have not been so carefully compared, and given the great geographic distance between records of the species it would be of interest to compare African and Australian specimens. Scoloplos (Leodamas) mazatlanensis described by Fauchald (1972) from deep water off western Mexico is here referred to Leodamas, but the species is not well described and illustrated and may not belong to this genus. The arrangement of the thoracic neuropodial uncini is not stated, only that 10 – 15 uncini are present per neuropodium. Further, the text suggests that there are numerous capillaries in these neuropodia as well, which if true would imply that the species belongs in Scoloplos sensu stricto. The original specimens need to be reexamined.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	Another species with an interesting history is Scoloplos cylindrifer originally described from South Island, New Zealand by Ehlers (1904). Ehlers had complete specimens up to 17 mm long and 115 setigers. This original description depicted a fairly typical orbiniid with a pointed prostomium, peristomium with a single ring, and parapodia consisting elongate, flattened notopodial lamellae and reduced neuropodia. All setae were described as thin hairy bristles (“ dünner feilkerbiger Borsten ”), undoubtedly referring to the camerated nature of most orbiniid capillaries. The presence or absence of thoracic neuropodial spines or uncini was not indicated. The branchiae were described and illustrated as single, but one was noted to have a protrusion, suggesting bifurcation. The second report of the species was by Augener (1914) from intertidal sands in SW Australia based on two specimens, one of which was missing the anterior end. A specimen from New Zealand was provided from the Bremer Museum for comparison, but it was not stated if this was one of the syntypes from Ehlers’ collection. The Australian specimen was larger, 42 mm long and with 210 segments. The nature of the parapodia and setae were not mentioned. Instead, a detailed description of the branchiae was provided; these were determined to have 2, 3, and 4 branches. The one figure (Augener 1914: Plate I, fig. 4) clearly shows dichotomous branching. Augener (1926) recorded the species from near Dunedin, South Island, New Zealand. He noted that the branchiae were from setiger 22 and had up to four branches; no information was provided on the thoracic neurosetae. The fourth report of the species was by Monro (1939) based on several specimens from Tasmania, Australia. One complete specimen was 30 mm long with 140 setigers. All setae were reported as camerated capillaries leading Monro to transfer the species from Scoloplos to Haploscoloplos. He noted that branchiae were branched with up to five filaments. Hartman (1957) referred to the species as Haploscoloplos cylindrifer and reviewed the reports and noted considerable variability within the species accounts, in particular that the branchiae began anywhere from setigers 17 – 50. None of these earlier reports made any mention of spines or uncini in the thoracic neuropodia; but projecting uncini were observed by Ehlers (1904) in the posterior neuropodia, a characteristic typical of many species of Leodamas. Furcate setae were not reported in any of these early accounts. In the same paper where she reviewed the history of Haploscoloplos cylindrifer, Hartman (1957) described a new species, Scoloplos (Leodamas) dendrobranchus from various intertidal habitats in South Australia. This was another species with dendritically branched branchiae with up to six filaments reported from setiger 18, or the first abdominal setiger. In addition to capillary setae, Hartman reported that this species lacked notopodial furcate setae but had 8 – 14 large thoracic neuropodial uncini arranged in a distinct J-shaped row anterior to the capillaries; these uncini were reported as blunt tipped, and with no hood. She also reported the presence of projecting aciculae in posterior neuropodia. All of these characters agree with the genus Leodamas as defined in this study for species of Group B, where large thoracic neuropodial uncini are present in 1 – 2 vertical rows and branchiae begin in posterior thoracic or anterior abdominal segments. Day (1975: 1977) reported on eight specimens from South Australia that he identified as Scoloplos cylindrifer that differed from earlier accounts in having instead of lacking a small group of curved, serrated hooks in addition to crenulate capillaries in thoracic neuropodia. He also had Monro’s specimens in the British Museum checked and they were reported to him as also having hooks in thoracic neuropodia. For this reason, Day (1975) synonymized Hartman’s (1957) S. dendrobranchus with S. cylindrifer. Day (1977) later identified numerous additional specimens of S. cylindrifer from most coasts of Australia and considered it to be one of the most common orbiniids he encountered. In the same paper, Day (1977) determined that because Monro (1993 a) had established Haploscoloplos cylindrifer as the type species of his genus Haploscoloplos Monro, that a new genus was required because the type species had an anterior row short hooks in the thoracic neuropodia in addition to capillaries and thus belonged to the genus Scoloplos. In addition to the Australian material, he examined a specimen from near Christchurch, South Island, New Zealand, near the type locality of the species and thus confirmed the presence of thoracic neuropodial hooks in the species from both New Zealand and Australia. He therefore proposed a new genus, Leitoscoloplos to include those remaining species formerly assigned to Haploscoloplos (see above for earlier account of Leitoscoloplos). Day & Hutchings (1979) summarized the Australian and other records for the species. Hartmann-Schröder (1981) as part of a series of papers on Australian polychaetes provided the first detailed description of the thoracic neurosetae of Scoloplos cylindrifer since Hartman (1957) (as S. (Leodamas) dendrobranchus). The thoracic neurosetae included both capillaries and uncini. The latter were arranged in a horseshoe-shaped double row with the anterior row extending from the top of the fascicle vertically, and then curving under and extending part way up the posterior border of the setal fascicle becoming a short second row (Hartmann-Schröder, 1981: Fig. 101). This is similar to what Hartman (1957) called a J-shaped row. The uncini have thick shafts, narrowing to a blunt tip; a lateral sheath is present together with transverse ribs on the concave side of the shaft. The uncini on the anterior row have less distinct ribs on the shaft than the posterior uncini (Hartmann-Schröder, 1981: Figs. 104 – 105). As in previous reports, furcate setae were not observed. Hartmann- Schröder (1981) also noted that flail setae were absent, branchiae were first present from setiger 18 with up to five branches, and observed abdominal neuropodia with two protruding aciculae (Hartmann-Schröder, 1981: Fig. 103). These observations by six different investigators eventually provided details sufficient to categorize the species. Based on the definition provided in the present study, the orbiniid species “ cylindrifer ” belongs to the genus Leodamas Group B and is included as such in Table 1. Leodamas cylindrifer is one of several species in the genus where a vertical anterior row of neuropodial thoracic uncini curves under other setae and continues again dorsally as a short posterior row. The status of Alcandra robustus described by Kinberg (1866) is uncertain. The only specimen, an anterior fragment from Brazil with the head and eight setigers, was examined by Hartman (1948, 1957). The specimen was reported as having a conical prostomium, branchiae from setiger 5, only capillaries in both noto- and neuropodia of setiger 1, and with uncini in palisaded rows from setiger 2. Uncini were illustrated by Hartman (1957) as curved with a blunt tip and with transverse rows of ribs on the convex side of the shaft. Due to the fragmented nature of the holotype, this species cannot be fully compared with other species or even confirmed as belonging to Leodamas. In the present study, eight species, three new to science are reported from South American and Antarctic seas. The type species, Leodamas verax is redescribed from new material off Argentina and a neotype is designated. Type specimens of five of Ehlers’ species have been examined and redefined, resulting in one being designated a synonym and another being resurrected from synonymy. Species / Character Shape of thorax in X- No. thoracic setigerous No. rows of thoracic Capillaries with Structure of thoracic neuropodial section segments neuropodial uncini thoracic neuropodial uncini uncini Group A: Species of Leodamas with branchiae from anterior thoracic setigers; thoracic neuropodial uncini typically in 3 or more vertical rows Leodamas verax Kinberg, Dorsoventrally flattened 22 – 24 3 vertical rows & 1 short Absent Blunt – tipped with groove on convex posterior row curving ventral to side; with weakly developed transverse Type species) rows 1 – 3 ribs along shaft Leodamas brevithorax Narrow, becoming depressed 15 – 17 4 vertical rows with first Few in dorsal tuft Uncini curved with rounded tip and Eibye – Jacobsen, 2002) or flattened from setiger 4 curving under 2 – - 3 and shaft with 5 – 12 transverse ridges forming row 4 Leodamas chevalieri Flattened, broad 20 – 27 4 – 5 vertical rows Present, long, becoming Uncini straight, narrowing at tip, blunt, Fauvel, 1902) more numerous with lateral hood Leodamas cochleatus Rounded, only weakly 10 – 29 (size related) 3 vertical rows & 1 short Absent Uncini of anterior setigers with straight Ehlers, 1900) flattened dorsally posterior row curving ventral to shaft, blunt tip and weak transverse rows 1 – 3 ribs; transitioning to uncini with curved expanded tips with subapical notch and prominent ribs on shaft Leodamas cirratus (Ehlers, Dorsoventrally flattened 21 – 32 3 long vertical rows & 1 short Absent Long, tapering; blunt-tipped with long) posterior row curving under vertical notch on concave side; weakly rows 1 – 3 developed transverses ribs on shaft Leodamas dendrocirris Dorsoventrally flattened. 17 – 18 4 – 5 vertical rows; arrangement Crenulate capillaries in Long, curved apically with blunt tip Day, 1977) not stated. single posterior row and transverse rows of ribs on convex side. Leodamas dubius Dorsoventrally flattened. 15 – 19 or 21 – 23 4 – 5; last row short Few with posterior row Long, curved apically to blunt tip; shaft Tebble, 1955) uncini with transverse ribs; Thai and Australian specimens with thickened hood, imparting bidentate appearance. Leodamas fimbriatus Not stated. 24 – 30 Up to 4 vertical rows of uncini; Absent Uncini of first row longest, thickest, Hartman, 1957) arrangement not stated. and with sharply curved, smooth tips; uncini of following rows thinner, less curved Leodamas gracilis (Pillai, Short, depressed or flattened. 13 – 17 1 anterior row of 3 – 4 heavy Crenulate capillaries in Two types: 3 – 4 anterior heavy, simple) spines; 2 – 3 vertical rows of posterior row of uncini spines; second curved spines with numerous hooded uncini; first hooded tip and transverse rows of ribs row curves under rows 2 – 3. on shaft …… continued on the next page Species / Character Shape of thorax in X- No. thoracic setigerous No. rows of thoracic Capillaries with Structure of thoracic neuropodial section segments neuropodial uncini thoracic neuropodial uncini uncini Leodamas hamatus Dean & Dorsoventrally depressed, 13 – 21 2 – 4 vertical rows & partial 5 th 2 – 7 thin capillaries in Two types: anterior 4 – 5 setigers with Blake, 2015 but not flattened. row dorsal tuft straight shaft, blunt tip and thin hood on convex side; uncini of following setigers with larger thickened hood, imparting bidentate appearance Leodamas hyphalos n. sp. Inflated first 3 – 4 setigers, 16 – 18 4 vertical rows; first row 2 – 3 capillaries in Shaft curved to straight, tapering to then depressed but not curving ventral to 2 and 3, then superior position to last rounded apex; shaft with irregular flattened merging with posterior row row of uncini transverse ribs Leodamas johnstonei (Day, Flattened dorsally, rounded 18 – 24 3 – 5 vertical rows Few in posterior row Shaft curving at tip; weakly serrated, 1934) ventrally with lateral flange Leodamas latum Dorsoventrally flattened ~ 20 Not stated, but “ setae arranged Present Elongate, curved to narrow tip, shaft Chamberlin, 1919) in vertical series. ” with numerous transverse rows. Leodamas marginatus Dorsoventrally flattened 14 – 20 3 vertical rows & 1 short 0 – few in tuft superior to Blunt-tipped with sub-terminal groove Ehlers, 1897) after first 3 setigers transverse row curving ventral 3 vertical rows of uncini or notch & low transverse crenulated to rows 1 – 3 ribs on shaft (SEM) Leodamas orientalis Broadly oval 18 – 21 4 – 5 vertical rows, 5 th row from 1 – 2 in uppermost Curved, blunt-tipped, with up to 9 Gallardo, 1967) New middle thoracic setigers, only location transverse ribs on concave side status ½ as long as 1 – 4. Leodamas Broad, dorsoventrally 11 – 13 3 – 4 vertical rows of uncini; Long, thin silky Distally curved, notched, with lateral perissobranchiatus n. sp. flattened arrangement not stated. camerated setae mixed flange and transverse rows of ribs with uncini along shaft Leodamas rubrus (Webster, Broadly oval, dorsoventrally 23 – 28 3 – 5; arrangement not stated. Few in uppermost Curved apically, with blunt tip and 1879) depressed location transverse ridges on convex side of shaft Leodamas thalassae Dorsoventrally flattened 12 – 15 2 curved rows of large uncini. A row posterior to Thick, curved apically, with blunt tip Amoureux, 1982) uncini and numerous transverse ridges on shaft Leodamas tribulosus Dorsoventrally flattened 22 – 25 5 – 7 dense vertical rows of Crenulated capillaries in Bent in posterior direction; tip with 2 Ehlers, 1897) uncini; first row curves under 2 rows posterior to pointed teeth followed by long groove rest of uncini, merging with uncini on convex side flanked by lateral; shaft short posterior row with rows of low transverse ribs. …… continued on the next page Species / Character Shape of thorax in X- No. thoracic setigerous No. rows of thoracic Capillaries with Structure of thoracic neuropodial section segments neuropodial uncini thoracic neuropodial uncini uncini Group B: Species of Leodamas with branchiae from posterior thoracic or anterior abdominal setigers; thoracic neuropodial uncini typically in 1 – 2 rows Leodamas acutissimus Only slightly flattened 14 – 20 3 – 4 rows Present in single row Uncini of anterior setigers smooth, Hartmann-Schröder, 1991) posterior to last row of curved with 4 – 5 transverse rows of uncini denticles; uncini of posterior setigers straight with lateral sheath and no rows of denticles Leodamas agrestis Nonato Broad, dorsoventrally 15 1 row, setigers 1 – 8; additional Present as dorsal tuft, Single row of uncini, curved, tapering Luna, 1970 depressed anterior row of 2 – 3 large, middle and posterior to pointed tip; large anterior spines heavy spines setigers 7 – 15 thoracic setigers short, thick, tapering to narrow tip Leodamas cylindrifer Dorsoventrally depressed 14 – 17 A single J-shaped row with 8 – Present with ca. 12 Simple, blunt, distally curved, with Ehlers, 1904) 14 uncini curving ventrally capillaries in a vertical lateral sheath or hood; shaft with under group of capillaries; fascicle transverse ribs uncini reduced to ~ 7 in posterior thoracic setigers. maciolekae n. sp. Flattened 40 2 rows, with 1 st row curving Absent Simple, weakly curved, without under 2 nd. transverse ribs madagascarensis Fauvel, Dorsoventrally flattened 24 – 30 2 rows, with 1 st curving under Few in a dorsal tuft Simple, blunt, straight; without 2 nd. transverse ribs mazatlanensis (Fauchald, Weakly dorsoventrally 15 Not stated, but 10 – 15 uncini Present “ numerous ” Simple, curved, with 10 – 15 transverse) flattened present. shallow ridges on convex side. minutus Lopez, Cladera cylindrical 13 1 – 2 rows (set 1 – 3), 2 rows (set Absent setigers 1 – 9; Simple, straight with weak transverse San Martin, 2003 4 – 13) present from setiger 10 ribs platythoracicus Lopez, Cylindrical anteriorly; flatted 19 1 (set 1) 1 – 2 uppermost in Simple, straight, without transverse ribs Cladera & San Martin, 2003 posteriorly 2 (set 2 – 13) fascicle 1 (14 – 19) texana (Maciolek & cylindrical 11 – 20 1 row of 5 – 9 uncini 1 – few, in dorsal tuft Simple, weakly curved, rounded tip, Holland, 1978) — Includes without transverse ribs Naineris sp. A of Taylor 1984).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	aciculae flail setae Begin	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	materials_examined	Type species) aciculae 62 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	acicula	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	transverse ribs to spines with curved and expanded tips with subapical notch and prominent ribs on shaft	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	hyaline hood thoracic neuropodial uncini. Islands; shallow subtidal, 598 m. Leodamas dendrocirris Noto: Absent; Absent 5 Thoracic notopodia divided into 2 – 5 Australia, New South Day 1977 Day, 1977) Neuro: 1 long acicula separate branches continuing on Wales, 65 m. with smooth bent tip. abdominal segments; thoracic neuropodia with a single postsetal lamella.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	projecting, slightly 15 abdominal segments, then curved to blunt tip. disappearing. …… continued on the next page Species / Character Emergent abdominal Abdominal Noto- Setiger Unique characters Geographic References noto- & neuropodial & neuropodial Branchiae Distribution aciculae flail setae Begin Leodamas gracilis (Pillai, Noto: absent; Absent 6 Presence of two kinds of thoracic Ceylon; Viet Nam, Pillai 1961; Gallardo) Neuro: 1 – 2 simple, neuropodial uncini: 3 – 4 heavy, simple shallow water; Andaman 1967; straight aciculae similar anterior spines; plus more numerous Sea, 19 – 38 m. Eibye-Jacobsen 2002 to heavy spines of uncini in 2 – 3 vertical rows with thoracic neuropodia hooded tip and transverse rows of ribs on shaft. Leodamas hamatus Dean Noto: absent; Absent 6 Heavy, curved uncini in abdominal Off Pacific Costa Rica, Dean & Blake 2015 Blake, 2015 Neuro: large, projecting neuropodia; change in structure of 11 – 26 m. acicula with hooked tip. thoracic neuropodial uncini from anterior to posterior of thorax. Leodamas hyphalos n. Noto: absent; Noto: 2 flail setae 6 Intersegmental annulations from Drake Passage in deep This study. Neuro: 1 – 2 blunt-tipped present; setigers 8 – 9; notopodial flail setae; water; 2888 – 4008 m. aciculae. Neuro: Absent	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	Leodamas latum Noto: absent Not stated. 5, stated as Anterior thoracic branchiae single, Off Panama, 588 m; off Chamberlin 1919; Fauvel Chamberlin, 1919) Neuro: 1 blunt acicula somite 6 by then divided into 3 – 9 palmately Burma, 457 m. 1932; Hartman 1957 (Fauvel 1932) Chamberlin arranged branches through middle abdominal segments; then number decreasing again in posterior abdominal segments Leodamas marginatus Noto: absent; Absent 6 Neuropodial subpodial lobes absent. Southern South Ehlers 1897; Ehlers, 1897) Neuro: 1 projecting America; widespread in Hartman 1957, 1966; acicula, distally curved sub-Antarctic and Knox 1998; This study Antarctic seas; intertidal to 1674 m Leodamas orientalis Noto: absent Neuro: 1 Absent 6 Furcate setae with nearly equal tynes; Viet Nam; Andaman Gallardo 1967; Eibye- Gallardo, 1967) New distally hooked acicula abdominal neuropodia with ventral Sea, 21 – 79 m. Jacobsen 2002 status cirrus Leodamas Noto: absent Absent 4 Branchiae single on anterior and Western Chile, 192 m. This study perissobranchiatus n. sp. Neuro: tip of acicula middle thoracic segments; becoming emergent palmately branched with 2, 3, and 4 branches in abdominal segments …… continued on the next page Species / Character Emergent abdominal Abdominal Noto- Setiger Unique characters Geographic References noto- & neuropodial & neuropodial Branchiae Distribution aciculae flail setae Begin Leodamas rubrus Noto: absent; Absent 6 Furcate setae with nearly equal tynes; E and SE United States; Webster 1879: Hartman Webster, 1879) Neuro: 1 heavy spine Last thoracic and anterior abdominal Gulf of Mexico; 1951, 1957; Taylor 1984 with curved, smooth tip segments with long, tapering postsetal intertidal to 200 m. lobe. Leodamas thalassae Noto: 1 present, pointed; Not stated 5 Prominent postsetal lobe in thoracic NE Atlantic, off Brittany Amoureux 1982 Amoureux, 1982) Neuro: 1 present, pointed neuropodia; relatively few thoracic coast of France, 850 – neuropodial uncini. 1400 m. Leodamas tribulosus Noto: absent; Absent 5 Large number of thoracic uncini each Western South America, Ehlers 1897; This study Ehlers, 1897) Neuro: 1 – 2 aciculae with curved posteriorly and with dorsal Patagonia; Argentina; blunt tips. groove terminating in two pointed intertidal to shallow teeth. subtidal Leodamas acutissimus Noto: not emergent; Noto: absent; 16 – 18, Thoracic neuropodial uncini transition Australia, Gladstone Hartmann-Schröder, 1991; Hartmann-Schröder, Neuro: thin curved Neuro: present posterior from 3 – 4 rows of smooth curved and Lizard Island, Zhadan (2015) 1991) spines, with tips thorax spines with transverse ribs to straight Qld, emergent spines with lateral sheath and no ribs. Leodamas agrestis Noto: not emergent; Absent 16, 1 st Last 9 – 10 thoracic setigers with three Off Brazil, 2 – 100 m Nonato & Luna 1970 Nonato & Luna, 1970 Neuro: not emergent abdominal large bent, pointed, acicular spines anterior to single row of pointed uncini	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	capillaries. maciolekae n. sp. Noto: single spine; Noto: Absent; 29, thoracic Large number of thoracic setigers (40); Argentina, 14 m This paper Neuro: single thin Neuro: Present, with abdominal neuropodial flail setae straight acicula with tapering mucron-like tip	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD063A0937FF31F864FD89FAB3.taxon	description	mazatlanensis Noto: not emergent; Not stated 12 Not well described; thoracic Off Western Mexico, Fauchald 1972 Fauchald, 1972) Neuro: 3 – 4 curved, neuropodial with fingerlike postsetal 2487 – 2560 m project lobe; abdominal neuropodia with ventral cirrus. …… continued on the next page Species / Character Emergent abdominal Abdominal Noto- Setiger Unique characters Geographic References noto- & neuropodial & neuropodial Branchiae Distribution aciculae flail setae Begin minutus Lopez, Noto: not emergent; Absent 12 – 16 Cylindrical thorax, not flattened; Pacific Panama, Lopez et al. 2003 Cladera & San Martin, Neuro: sigmoid acicula setigers 1 – 3 uniramous, notosetae intertidal absent. platythoracicus Lopez, Noto: not emergent; Absent 20, 1 st Thorax cylindrical setigers 1 – 5, then Pacific Panama, Lopez et al. 2003 Cladera & San Martin, Neuro: single, brown, abdominal distinctly flattened; thoracic neuro intertidal straight acicula uncini in 1 row on setiger 1, then 2 rows, again reduced to 1 row setigers 14 – 19. texana (Maciolek & Noto: not emergent; Absent 2 nd to 4 th Thoracic neuropodial uncini in single NE Colombia; Gulf Maciolek & Holland 1978; Holland, 1978) — Neuro: narrow, thin, tip abdominal row throughout of Mexico, Taylor 1984; Granados- Includes Naineris sp. A emergent Louisiana-Texas, 2 – 5 Barba & Solís-Weiss 1997 b Taylor (1984). m treadwelli (Eisig, Noto: not emergent; Absent Last Thoracic neuro uncini transition from 2 Caribbean; Puerto Treadwell 1901; Hartman) Neuro: not emergent, or thoracic or rows to 1 row anterior to posterior. Rico; NE Colombia; 1957; Maciolek & Holland only the tip 1 st Pacific Mexico, 6 – 1978; Leon-González & abdominal 220 m Rodríquez 1996; Granados- Barba & Solís-Weiss 1997 a Accounts from West Africa (Tebble 1955) and Indo-Pacific (Eibye-Jacobsen 2002; Zhadan et al. 2015) likely represent different species. (2) Accounts from Panama (Chamberlin 1919) and Burma (Fauvel 1932) may represent different species.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062E0930FF31FF7CFBE1F930.taxon	materials_examined	Material examined. Uruguay, IBM Sta. N- 254, 27 – 30 m (1, USNM 1013643); IBM Sta. N- 1071, 36 – 42 m, sand and shells (1, USNM 1013642). — Argentina, IBM Sta. 2287 (R / V A. Saldanha), 38 ° 05 ′ S, 56 ° 43.5 ′ W, 67 m, (1, USNM 1013644). — Argentina, intertidal collected by J. M. Orensanz: Bahía de San Blas, north of Riacho Jabali, Oct 1968 (1, JAB); NE of Isla Jabali, intertidal, Apr 1970 (3, 21, and 15 specimens USNM 1013646 – 8); Riacho Jabali, intertidal, muddy sand, Oct 1968 (17, USNM 1013652); Bahía de San Antonio, oeste, Marejada norte. coll. R. Olivier and J. M. Orensanz, 6 Feb 1971, intertidal (15, USNM 1013655); 8 Feb 1971, intertidal (1, USNM 1013656); 9 Dec 1971, intertidal (1, USNM 1013650); 11 Dec 1972, intertidal (3, USNM 1013653); Golfo San Matías, IBM Sta. SAO-III- 1 0 41, intertidal, sandy gravel, 1972, neotype (USNM 1013645); Las Grutas, intertidal, under mussel bed, 7 Feb 1971, coll. J. Escofet and J. M. Orensanz (7, USNM 1013651).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062E0930FF31FF7CFBE1F930.taxon	description	Description. A large species, up to 15 cm long, 2.8 mm wide, for 340 setigers. Color in alcohol: light tan to flesh colored, sometimes with dusky pigment patch in middle of prostomium. Body dorsoventrally flattened in thoracic region, rounded in abdominal region; thoracic region with 22 – 24 setigers, last of which is transitional; peristomial segment and all setigerous segments readily distinct from one another; individual segments without additional annulations (Fig. 25 A). Branchiae from setiger 5 – 6, continuing to end of body; each branchia broad basally, tapering distally (Fig. 25 A – C). Prostomium triangular in shape, bluntly pointed on anterior margin; proboscis saclike, with numerous lobes (Figs. 25 A, 26 A); peristomium with one simple achaetous ring, prominent anterolateral nuchal slits present (Fig. 26 A, inset); eyespots absent (Fig. 25 A). Thoracic parapodia well developed, with conspicuous branched notopodial lamellae (Fig. 25 A – B) and numerous golden neuropodial uncini. Notopodia with single notopodial lamella to setiger 2 – 6, becoming double, then triple or quadruple from about setiger 4 – 16 (Fig. 25 A – B); branched notopodia sometimes continuing on first or second abdominal setiger. Neuropodia of thoracic setigers 1 – 20 without lobes or lamellae (Fig. 25 B), from setiger 21 – 22 or transition to abdominal region, a single ventral cirrus and sometimes a second ventral cirrus (or subpodial lobe) present; these continuing into abdominal region (Fig. 25 C). Abdominal parapodia all similar, lacking interramal cirri; ventral cirrus present to about setiger 65 (Fig. 25 C), second ventral cirrus (or subpodial lobe) sometimes present from about setigers 31 – 40; notopodial postsetal lamella of last few thoracic setigers continuing through abdominal region. Notosetae including fascicles of crenulated capillaries in thoracic and abdominal notopodia; 1 – 3 furcate setae in posterior thoracic and abdominal notopodia; 1 – 2 straight, tapering notopodial spines in abdominal notopodia with furcate setae and capillaries (Fig. 26 E); in light microscope furcate setae with unequal tynes, connected by membrane consisting of fine needles (Fig. 25 F); in SEM, furcate setae with 11 – 12 delicate needles on each side with apical needles merging with tynes (Fig 26 F), tynes with minute openings in tips, shafts with transverse rows of fine barbs (Fig. 26 F). Thoracic neuropodial uncini arranged in three long vertical rows and one shorter posterior row curving ventrally under rows 1 – 3 (Fig. 26 B – C); uncini golden in color, thick, blunt-tipped, with lateral groove or notch, some with dark internal core (Fig. 25 D – E); in SEM subterminal groove present on convex side and with elongate shaft bearing weakly developed transverse ribs (Fig. 26 D); capillaries entirely lacking. Abdominal neuropodia with 1 – 2 projecting aciculae (Figs. 25 G, 26 G) and fascicle of delicate capillaries (Fig. 25 C). Pygidium short, bulbous, with anus directed dorsally, surrounded by lobed border bearing two pair of tapering anal cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062E0930FF31FF7CFBE1F930.taxon	discussion	Remarks. Leodamas verax was described by Kinberg (1866) from depths of 62 m off southeastern South America. In that paper, Kinberg established the genus Leodamas, with L. verax as the type species. The species has gone unreported since its original description, although Hartman (1948; 1957) redescribed the holotype which was archived in the Swedish Museum. Subsequent to Hartman’s examination, the holotype appears to have been lost; curators at the Swedish Museum have not been able to locate the specimen. I also requested a search of the collections at the Allan Hancock Foundation, on the possibility that Hartman might have inadvertently retained the holotype in her research collections, but the type was not located there. Because of the importance of L. verax to the nomenclature of the genera Scoloplos and Leodamas, a neotype has been designated from among the abundant new material from Argentina to replace the lost holotype (USNM 1013645).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062E0930FF31FF7CFBE1F930.taxon	distribution	Distribution. Known only from off Uruguay and Argentina, intertidal to 62 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06280932FF31F8AFFD7FFACD.taxon	materials_examined	Material examined. Argentina, IBM Sta. Comp IV- 62, 21 Mar 1964, 37 ° 50 ′ S, 57 ° 21 ′ W, 14 m, holotype (USNM 1013916).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06280932FF31F8AFFD7FFACD.taxon	description	Description. A single nearly complete specimen measures 3 mm wide and 50 mm long for 167 setigers. Body anteriorly flattened, with first five segments somewhat inflated dorsally due to contained proboscis. Thorax 40 setigers long, with last two segments somewhat transitional; branchiae long, narrow, from setiger 29; first neuropodial postsetal lamellae from setiger 34. Color in alcohol: brown. Prostomium sharply pointed (Fig. 27 A), with distinct anterolateral nuchal slits at junction with peristomial segment. Anterior thoracic parapodia simple rings; with short notopodial postsetal lamella (Fig. 27 A – B); abdominal notopodia elongate, narrow. Neuropodial postsetal lamellae first present from setiger 34, grading into abdominal neuropodial morphology on transitional setigers 39 – 40; abdominal neuropodia elongate, with a single laterally directed ventral cirrus (Fig. 27 C); interramal cirri lacking. Thoracic notosetae all thin, crenulated capillaries; anterior abdominal notosetae including a single emergent spine, 6 – 8 long capillaries, and 1 – 4 furcate setae bearing unequal tynes connected by row of delicate needles on inner edges (Fig. 27 D). Thoracic neuropodial uncini maximally numbering about 40, arranged in two rows, with anterior row curving ventrally under second row and continuing dorsally to enclose second row as a short third row or extension (Fig. 27 B, inset); uncini simple, most worn, slightly curved, lacking distinct ribs (Fig. 27 E – F); capillaries entirely absent in thoracic neuropodia. Abdominal neurosetae including a single thin acicula, a single, very thin capillary (Fig. 27 H), and a single flail seta; flail setae with abruptly tapering mucron-like tips (Fig. 27 G).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06280932FF31F8AFFD7FFACD.taxon	etymology	Etymology. This species is named for Dr. Nancy J. Maciolek, polychaete systematist, in recognition of her prior work on similar species of Orbiniidae.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06280932FF31F8AFFD7FFACD.taxon	discussion	Remarks. Leodamas maciolekae n. sp. is referred to Leodamas because the thoracic neuropodial setae are dominated by large, conspicuous uncini and capillaries are absent. Leodamas maciolekae n. sp. belongs to the group of species having branchiae from posterior thoracic or anterior abdominal setigers (Table 1). There are four species that are closely related to L. maciolekae n. sp.: L. minutus, L. platythoracicus, L. texana, and L. treadwelli .. The main characters differentiating these five species are listed in Table 1. L. maciolekae n. sp. differs from the other four species in having many more thoracic setigers (40 instead to 11 – 22), complete absence of accompanying capillaries in the thoracic neuropodia, in having abdominal neuropodial flail setae instead of lacking them, by having the branchiae from a late thoracic setiger instead of transitional or abdominal segments. In the latter character, the species is closest to L. treadwelli. Further, the arrangement of thoracic neuropodial uncini into two rows, branchiae first present from posterior thoracic setigers and a distinctly dorsoventrally flattened thorax is also similar to that of L. treadwelli. However, the greater number of thoracic setigers (40 vs. 14 – 22) and the presence of very delicate flail setae in the abdominal neuropodia of some setigers in L. maciolekae n. sp. have not been reported for L. treadwelli and its relatives.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06280932FF31F8AFFD7FFACD.taxon	distribution	Distribution. Argentina, shallow subtidal.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062A094EFF31FABEFA40FB5F.taxon	materials_examined	Material examined. Chile, Patagonian region, Straits of Magellan, Eltanin Sta. 11 - 960, 64 m (1, USNM 60649). — Tierra del Fuego, Hero Sta. 656, 18 m (2, USNM 60676); Staten Island, Hero Sta. 71 - 2 - 6, 0 – 1 m (2, USNM 60675). — Falkland Islands, Hero Sta. 672, 50 m (1, USNM 60677); Sta. 676, 18 m (1, USNM 60678). — Drake Passage, Eltanin Sta. 9 - 740, 384 – 494 m (1, USNM 56459); Sta. 12 - 1089, 641 m (1, USNM 56461). — South Orkney Islands, Eastwind Sta. 1966 - 028, 188 – 192 m (2, USNM 67615). — N. of Elephant Island, ANDEEP I, R / V Polarstern, Sta. PS- 61 / 045 - 1, Otter trawl, 196 – 269 m (1, SEM, JAB); South Shetland Islands, Hero Sta. 700, 38 m (1, USNM 60682); Sta. 1064, intertidal (2, USNM 60681); Eastwind Sta. 0 8, 97 – 113 m (3, USNM 67614); Eltanin Sta. 6 - 410, 220 – 240 m (12, USNM 56463, 60648); Sta. 12 - 1003, 210 – 230 m (1, USNM 56466). — Antarctic Peninsula, off Anvers Island, Hero Sta. 957, 190 m (1 USNM 60679); Sta. 972, 40 m (1, USNM 60680); Sta. 1101, 360 – 370 m (1, USNM 60683); Arthur Harbor, Sta. 1897 (1, USNM 69382). — Ross Sea, western sector, Eltanin Sta. 32 - 2075, 568 m (1, USNM 60670); Sta. 32 - 2085, 468 – 482 m (1, USNM 60671); Sta. 32 - 2088, 430 – 433 m (USNM 60672); Staten Island Sta. 1, 201 m (1, USNM 67613); off Ross Ice Shelf, Eltanin Sta. 32 - 2065, 473 – 475 m (1, USNM 60669). — Ross Sea, eastern sector, Eltanin Sta. 27 - 1869, 1565 – 1674 m (4, USNM 60651); Sta. 27 - 1870, 659 – 714 m (9, USNM 60652); Sta. 27 - 1885, 311 – 328 m (6, USNM 60653); Sta. 27 - 1896, 70 – 81 m (2, USNM 60654); Sta. 27 - 1897, 362 – 375 m (1, USNM 60655); Sta. 27 - 1901, 445 – 448 m (1, USNM 60656); Sta. 27 - 1903, 640 – 646 m (1, USNM 60657); off McMurdo Sound, Eltanin Sta. 27 - 1907, 891 m (2, USNM, 60658); Sta. 27 - 1916, 728 m (1, USNM 60659); off Moubray Bay, Eltanin Sta. 32 - 1995, 344 – 348 m (3, USNM 60660); Sta. 32 - 1996, 348 – 352 m (1, USNM 60661); Sta. 32 - 1997, 523 – 528 m (7, USNM 60662); Sta. 32 - 2012, 589 – 608 m (1, USNM 60663); Sta. 32 - 2014, 567 m (1, USNM 60664); Sta. 32 - 2031, 535 m (9, USNM 60665); off Terra Nova Bay, Eltanin Sta. 32 - 2035, 876 m (1, USNM 60666); Sta. 32 - 2036, 334 – 335 m (1, USNM 60667); Sta. 32 - 2039, 565 – 569 m (1, USNM 60668); off Cape Adare, Sta. 32 - 2125, 160 – 164 m (1, USNM 60673); Deep Freeze III, Atka Sta. 23, 392 m (1, USNM 67609); Robertson Bay, Deep-Freeze I, Edisto Sta. 3, 27 m (1, USNM 67605); Moubray Bay, Deep Freeze IV, Northwind Sta. 8, 134 m (1, USNM 67612). — McMurdo Sound, Deep Freeze I, Edisto Sta. 8, 321 m (5, USNM 67604); Deep Freeze II, Glacier Sta. 2, 384 m (1, USNM 67606); Sta. 6 B, 250 m (2, USNM 67607); Deep Freeze III, Glacier Sta. BL- 16, 140 m (2, USNM 67611); Burton Island Sta. 3, 433 m (8, USNM 67608); off Cape Royds, Ross Island, U. S. Navy Antarctic Expedition, Sta. 99, Jan 29, 1948, 106 m, coll. D. C. Nutt (11, USNM 23869); Sta. 104, 106 m (5, USNM 23853 – 4); near shore Cape Evans, off Scott’s Hut, 16 Jan 2000, 9 m, coll. S. Kim (1, JAB, SEM). — Budd Coast, Vincennes Bay, near Wilkes Station, Deep Freeze III, Atka Sta. 29, 135 m (1, USNM 67610). — Weddell Sea, Glacier Sta. 69 - 1, 513 m (6, USNM 46612). — South Pacific Ocean, SE of New Zealand, near Antipodes Island, Eltanin Sta. 32 - 2143, 2010 – 2100 m (3, USNM 60674).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062A094EFF31FABEFA40FB5F.taxon	description	Description. Largest specimens posteriorly incomplete, 62 mm long, 3 mm wide for 54 setigers; type specimens reported to be 80 mm long for 102 segments (Ehlers, 1897). Color of larger specimens brown; smaller specimens opaque white to light tan. Thoracic region with peristomium and first three setigers only slightly flattened, thereafter dorsoventrally flattened; abdominal region cylindrical in cross section. Thorax with 14 – 20 setigers, 11 – 19 according to Hartman (1966); transition to abdominal region abrupt. Prostomium triangular in shape, narrowing to pointed anterior end (Fig. 28 A), appearing somewhat flattened in lateral view (Fig. 29 A); nuchal organ a broad curving slit or groove on either side (Fig. 29 A). Peristomium with one simple asetigerous ring, distinctly separated from setiger 1 (Figs. 28 A, 29 A). Thoracic parapodia all similar; notopodia with cirriform, postsetal lamellae (Fig. 28 A); notopodial lamellae short on setiger 1, becoming full size by setiger 6 – 8 (Fig. 28 A); thoracic neuropodia with swollen lobes from which rows of uncini emerge (Fig. 28 B); a small triangular-shaped neuropodial postsetal lobe sometimes present from middle body segments. Abdominal parapodia lacking ventral and interramal cirri; each notopodium with long, cirriform postsetal lamella (Fig. 28 D); neuropodium elongated truncate (Fig. 28 D). Notosetae including crenulated capillaries in thoracic and abdominal notopodia; furcate setae (Fig. 28 E) present in abdominal notopodia. Furcate setae with unequal tynes connected by web of fine needles (Fig. 28 E). Thoracic neuropodia with three long dorsoventral rows and one short, curved fourth transverse row of yellow uncini (Fig. 28 C) curving ventral to first three rows; first and fourth row sometimes appearing to merge into Ushape ventral to rows 3 and 4; uncini thick, blunt-tipped, with lateral notch or groove (Fig. 28 F – G); with SEM groove broad and flattened, continuing from rounded apex and merging with low transverse crenulated ribs extending around shaft, these not seen in light microscopy (Fig. 29 C); with small group of crenulated capillaries sometimes present superior to three rows of uncini, especially in juveniles. Abdominal neuropodia with few smooth, non-crenulated capillaries; embedded acicula present in notopodia; single emergent acicula with curved tip present in neuropodia. Branchiae from setiger 6, continuing to end of body; each branchia thick, cirriform, tapering to rounded tip, with thick rows of cilia on medial side (Figs. 28 C, 29 B).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062A094EFF31FABEFA40FB5F.taxon	biology_ecology	Biology. Leodamas marginatus is one of the few species of Antarctic polychaetes to be the subject of an investigation of its reproduction, life history, and ecology. Hardy (1977) studied two populations occurring between the littoral zone and 35 m depth on Signi Island in the South Orkney Islands (60 ° 42 ′ S; 45 ° 39 ′ W). Hardy (1977) considered his specimens of L. marginatus to be small, but they were larger than any encountered in the present study, being up to 99 mm long for 185 segments. Hardy (1977) found the male: female ratio to be 1: 1.85, with 38 % of the population being juveniles. In midwinter (July) the species was found to spawn a single cocoon containing an average of 551 eggs with an average diameter of 600 µm. Embryos develop slowly to the 3 – 4 segment stage by September. At that time the larvae hatch and burrow into the substratum where they complete their development, with metamorphosis occurring in December and January. Development is therefore direct, without any planktic larval stage. Another 30 months are required before this cohort spawns. Hence, Hardy (1977) was able to determine that three years are required for one generation of this species to develop and reproduce. Mature females live at least five years and may produce a single cocoon in each of two or three spawning seasons. Averincev (1982) working in shallow waters in the Davis Sea found the species on rock faces with a thin layer of silt at a depth of about 25 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062A094EFF31FABEFA40FB5F.taxon	discussion	Remarks. Leodamas marginatus is reported to have only uncini in thoracic neuropodia (Hartman, 1957). Some specimens in the present collection, however, have a superior group of long crenulated capillaries located dorsal to the uncini. These capillaries normally occur in the smaller specimens and juveniles. Leodamas marginatus mcleani was distinguished from the stem form by Benham (1921) because a separate group of uncini was present posterior to the three main rows. This character appears to be typical of the species as a whole, however, and a subspecies is not supported; further in some instances, the shorter fourth row merges ventrally with the first row forming a U-shape of uncini ventral to rows 2 and 3. This arrangement is similar to several other species of Leodamas. See further comments with L. cirratus and L. hyphalos (below). Scoloplos (Leodamas) naumovi described by Averincev (1982) from shallow waters of the Davis Sea is not well described, but agrees with the characters reported here for L. marginatus.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD062A094EFF31FABEFA40FB5F.taxon	distribution	Distribution. South America, Straits of Magellan and Patagonian regions; Falkland Islands; sub-Antarctic latitudes off SE Argentina and SE New Zealand; Antarctic Peninsula; Ross Sea; Weddell Sea; Intertidal to 1674 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0656094BFF31FB1FFCAFFF14.taxon	materials_examined	Material examined. Argentina, offshore, 190 km E Puerto San Julien, Santa Cruz, about 280 km NW of Falkland Islands, 49 ° 35 ′ S 64 ° 43 ′ W, 127 m, holotype of Arica cirrata (ZMH V 1224); R / V Vema Sta. V- 17 - 86, SE of Camarones, 225 – 227 m, 11 Jun 1961 (4, LACM-AHF Poly 5034); R / V Vema Sta. V- 18 - 12, continental slope E of Deseado, 424 – 428 m (2, LACM-AHF Poly 5030). — Argentina, nearshore, IBM Sta. Mej- 12, 24 m (1, JAB); IBM Sta. H- 17, 16 m (1, USNM 1013659); IBM Sta. N- 1055, 92 – 96 m (1, SEM stub, USNM 1013663); San Antonio Oeste, Marejada Norte (1, USNM 1013661); Golfo San Matías, Piedra Coloradas, Feb 1972, coll. Escofet and J. M. Orensanz (2, USNM 1013660); IBM Sta. Mej- 12 (1, USNM 1013662). — Falkland Islands, Port William, 3 Sep 1902, Swedish Antarctic Expedition 1901 – 1903, Sta. 52, 51 ° 40 ' S; 57 ° 44 ' W, 17 m, in sand (1, SMNH 3106); Port Stanley, 9 Apr 1927, coll. W. S. Schmidt (1, USNM 24341). — Chile, Straits of Magellan, Eltanin Sta. 7 - 967, 81 m (1, USNM 56465). — Tribune Bank, 52 ° 38 ′ S, 70 ° 00 ′ W, 46 m, sand and gravel, coll. E. Nordenskold, holotype of Aricia ohlini (SMNH 551). — South Orkney Islands, Eltanin Sta. 12 - 1079, 593 – 598 m (1, USNM 56467).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0656094BFF31FB1FFCAFFF14.taxon	description	Description. Holotype (ZMH V 1224) incomplete, 24 mm long, 1.5 mm wide for 73 setigers; thoracic region narrow, with 27 setigers, flattened at first, becoming more rounded in abdominal region. Falkland Islands specimen (SMNH 3106) incomplete, about 17 mm long and 1.5 mm wide for 54 setigers; thoracic region narrowing anteriorly, slightly depressed, with 32 setigers, last four setigers increasingly smaller, with fewer uncini. Tribune Bank specimen (SMNH 551) also incomplete, 17 mm long and 1.5 mm wide for 47 setigers; thoracic region with 21 setigers. Color in alcohol: brown. Prostomium triangular in outline, tapering anteriorly, but not acutely pointed; without eyespots; multi-lobed proboscis present (Fig. 30 A); paired nuchal organs present dorsolaterally at border with peristomium (Fig. 29 D, inset). Peristomium with one well-developed achaetous ring distinctly separated from prostomium and first setiger (Figs. 29 D, 30 A). Notopodial postsetal lobes from setiger 1, short, fingerlike at first, then increasing in length, becoming cirriform by setigers 4 – 5 (Figs. 29 D, 30 B), continuing through abdominal segments. Thoracic neuropodia with setae arising from elongate thickened lobe; with short, conical postsetal lobe first present from middle of neuropodium from about setiger 25 or last 3 – 7 thoracic setigers (Fig. 30 B); with short, cirriform subpodial lobe resembling ventral cirrus first present from last 2 – 6 thoracic setigers, continuing posteriorly through 18 – 20 abdominal setigers (Fig. 30 B – C). Abdominal neuropodia with thickened elongated lobes bearing short cirriform postsetal lobe (Fig. 30 C). Thoracic and abdominal notosetae including fascicles of crenulated capillaries and 3 – 4 short, furcate setae; furcate setae with unequal tynes, connected by thin webbing composed of very fine needles and with smooth shaft (Fig. 30 D); with SEM fine needles between tynes numbering 7 – 8 on a side, merging with tynes; each tyne with expanded apex, narrowing to bluntly pointed tip, but with narrow, elongate opening on inner border of tyne (Fig. 29 H); shaft with transverse rows of minute barbs (Fig. 29 H). Thoracic neuropodial uncini arranged in three long vertical rows and one short posterior row, similar to S. marginatus (Fig. 29 D – E), without accompanying capillaries; uncini blunt tipped, with weakly developed subapical notch or groove and with smooth shaft (Fig. 30 E – F); with SEM subapical groove, elongate, flattened extending about one-third distance to point of emergence from neuropodium, rest of shaft with weakly developed transverse ribs (Fig. 29 E – F); abdominal neurosetae including capillaries and an acicular spine sometimes with thin hyaline hood (Fig. 30 G), sheath not apparent in SEM (Fig. 29 G). Branchiae from setiger 6 (Figs. 29 D, 30 A), each broad, basally tapering to prolonged, nipple-like extension; with lateral cilia visible (Fig. 30 B – C). Branchial bases of some abdominal segments connected with low ciliated crest. Pygidium of specimen from USNM 1013660 with anus directed posteriorly, surrounded by dorsal pair of thick lobes and four pairs of lateral cirri; dorsal most pair longest, weakly moniliform, one with bifurcate tip, other with single tapering tip; two middle pair short, stubby, sometimes one missing; ventral most pair short, narrow, tapering to pointed tip.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0656094BFF31FB1FFCAFFF14.taxon	discussion	Remarks. The holotype was collected at a depth of ca. 125 m offshore SW Argentina and approximately 280 km NW of the Falkland Islands. The type specimen agreed very well with Ehlers’ (1887) original account both with size, number of segments, and morphology. The Falkland Islands specimen was examined by Hartman (1953: 38) who found it agreed with Ehlers (1897) original account; my examination of this specimen confirms this identification. Ehlers’ holotype is 24 mm long for 73 segments with 27 thoracic segments; the largest specimens in the new collections are 17 mm long for 54 segments with 32 thoracic segments. The type specimen of Aricia ohlini from the Straits of Magellan also agrees well with Leodamas cirratus. Leodamas cirratus closely resembles L marginatus and L. cochleatus in the arrangement and form of the thoracic neuropodial uncini, which are arranged into four vertical rows and have grooves on one side of the tip and transverse ridges or rows of minute barbs along the shaft seen best in SEM. In L. cirratus, the uncini are not accompanied by capillaries, whereas superior capillaries are sometimes present in L. marginatus. Leodamas cirratus has a single subpodial lobe or ventral cirrus from posterior thoracic and some abdominal segments; this lobe is lacking on L. marginatus. The prostomium of L. cirratus is more acutely pointed and the anterior thoracic region is less distinctly tapered than in L. marginatus. Further, the thoracic region of L. cirratus is more dorsoventrally flattened than in L. marginatus. Differences with L. cochleatus include the presence of thoracic neuropodial uncini with a broad, heavily notched apex and with distinct transverse ridges on the shafts. Additionally, L. cochleatus has abdominal notopodial acicular spines in addition to neuropodial (see below). The presence of moniliform pygidial cirri appears to be unusual among orbiniids, but these have not been well studied.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0656094BFF31FB1FFCAFFF14.taxon	distribution	Distribution. Off the SE coast of Argentina, shallow subtidal to 225 – 428 m; Falkland Islands 17 – 127 m; Straits of Magellan, 45 – 80 m; South Orkney Islands, 593 – 598 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06530945FF31FEF6FBEDFEDC.taxon	materials_examined	Material examined. Chile, Straits of Magellan, Tribune Bank, 52 ° 38 ′ S, 70 ° 00 ′ W, 46 m, sand and gravel, coll. E. Nordenskold, holotype of Aricia cochleata (SMNH 549). — Off Argentina, E of Mar del Plata, R / V Vema Station, V- 17 - 101, 450 – 454 m, 19 Jun 1961 (5, LACM-AHF Poly 5043; 3, LACM-AHF Poly 5045).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06530945FF31FEF6FBEDFEDC.taxon	description	Description. Holotype (SMNH 549) incomplete, 32 mm long, 2 mm wide for 110 setigers, color in alcohol pale yellow. Argentinean specimens all incomplete, smaller, 8 – 10 mm long, 0.8 – 1 mm wide, with 24 – 30 setigers (LACM-AHF Poly 5043); juveniles also present, one mostly complete, 4.5 mm long, 0.3 mm wide, with 40 setigers (LACM-AHF Poly 5045), color in alcohol tan. Body of all specimens flattened dorsally throughout, rounded ventrally, more so in the abdominal segments; body widest in thoracic segments, tapering posteriorly. Prostomium triangular in outline, tapering anteriorly to narrow, blunt tip (Fig 31 A); without eyespots; paired nuchal organs narrow slits, dorsolateral at border with peristomium. Peristomium with one achaetous ring only vaguely separated from prostomium, but well separated from first setiger (Fig. 31 A). Holotype with 29 setigers in thoracic region; smaller Argentinean specimens with 10 – 11 thoracic setigers. Notopodial postsetal lobes from setiger 1, fingerlike in shape, well developed from the first, increasing in size over thoracic region (Fig. 31 A), continuing through abdominal segments. Thoracic neuropodia elongate thickened lobes, with no postsetal lobe or lamella present; thoracic uncini arranged in three elongate rows, with the first appearing to curve ventrally forming a fourth row behind the third, similar to that of L. marginatus and L. cirratus. Abdominal neuropodia thickened elongated lobes, with short ventral cirrus on apex of neuropodium and prominent cirriform subpodial lobe at base of neuropodium (Fig. 31 B) present from first present abdominal setigers, continuing posteriorly through on all abdominal segments. Thoracic notosetae including fascicles of crenulated capillaries; abdominal notosetae including capillaries, 1 – 2 straight spines with narrow pointed tips (Fig. 32 F), and 1 – 3 furcate setae (Figs. 31 I, 32 H); furcate setae each with unequal tynes bearing fine needles; shaft smooth (Figs. 31 I, 32 H). Thoracic neuropodia with uncini arranged in three long vertical rows and one short posterior row, similar to L. marginatus and L. cirratus; without accompanying capillaries; uncini of anteriormost 2 – 3 setigers with straight shaft bearing weakly developed transverse ribs and with a rounded narrowing apex; with elongate narrow groove on one side (Figs. 31 C – E, 32 A – C); subsequent setigers with shaft of uncini developing prominent transverse ribs or rows of blunt barbs; with tip of uncini becoming expanded, curved, blunt, with subapical pocket or notch on concave side (Figs. 31 F – H, 32 D – E). Abdominal neurosetae including capillaries and 1 – 2 acicular spines with tip narrowing to curved blunt tip (Fig. 32 G). Branchiae from setiger 6, each broad, basally tapering to prolonged, narrow apical extension (Fig. 31 A – B). Pygidium unknown.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06530945FF31FEF6FBEDFEDC.taxon	discussion	Remarks. Aricia cochleata and A. ohlini were both briefly described but not illustrated by Ehlers (1900) from the same locality in the Strait of Magellan and subsequently fully described and illustrated in Ehlers (1901). Augener (1926) synonymized A. cochleata with A. ohlini based on collections from New Zealand. He did not examine the original collections and provided little justification for the synonymy. Hartman (1957, 1966), Rozbaczylo (1985) and others, however, recognized and perpetuated this synonymy with little or no discussion despite there being clear differences between the two species in Ehlers’ (1901) published descriptions and illustrations. Further, if these two species were synonyms, then A. cochleata would have to be the valid name, having been described first in the same paper by Ehlers (1900). Both species names were referred to Scoloplos (Leodamas) by Hartman (1957) and are clearly species of Leodamas as defined in the present paper. Despite the assumption of synonymy, an inspection of the descriptions of these two species suggests that they are different. This was verified by examining the type specimens and additional collections. In the present paper, Leodamas ohlini becomes a synonym of L. cirratus and L. cochleatus is redescribed and resurrected as a distinct and valid species. The main difference between Leodamas cirratus (with L. ohlini as a synonym) and L. cochleatus is with the nature of the thoracic neuropodial uncini. In L. cirratus, these uncini are relatively simple, straight-shafted with a weakly developed subapical notch or groove; in SEM weakly developed transverse ridges were observed. In contrast, the thoracic neuropodial uncini of L. cochleatus exhibit a distinct change in structure from those of the anteriormost 2 – 3 setigers where uncini have a relatively smooth, straight shaft bearing weakly developed transverse ridges and a narrow, rounded apex and an elongate narrow groove on one side. These uncini are replaced in middle and posterior thoracic neuropodia by spines with distinct transverse ribs or rows of blunt barbs on the shaft and with the tip of the uncini becoming expanded, curved, blunt, and bearing a subapical pocket or notch on the concave side. These differences with the thoracic uncini between L. cochleatus and L. cirratus (as L ohlini) were clearly described and illustrated by Ehlers (1901); L. cirratus is most closely related to L. marginatus (see above). Additional features of L. cochleatus not seen in L. cirratus are with the presence of abdominal spines (aciculae) in the neuropodia and uniquely, in the notopodia (Fig. 31 B). The neuropodial spines number 1 – 2 and are weakly curved and blunt-tipped apically (Fig. 32 F – G). The notopodial spines number 1 – 2 and are straight and also bluntly tipped (Fig. 31 B). Leodamas hamatus recently described from off Costa Rica by Dean & Blake (2015), is another species where the neuropodial uncini change morphologically from anterior to posterior thoracic setigers. However, in contrast to L. cochleatus, the posterior neuropodial spines of L. hamatus develop a prominent, thickened hood-like structure on the convex side of the curved spines. In addition, the abdominal neuropodial uncini of L. hamatus are large, heavy and curve to a pointed tip instead of being of being narrow and blunt-tipped.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06530945FF31FEF6FBEDFEDC.taxon	distribution	Distribution. Offshore Argentina, to 454 m; Chile, Straits of Magellan; 46 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065D0946FF31F94EFEE5F91F.taxon	description	Scoloplos (Leodamas) spp. Hartman 1967: 108 (in part).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065D0946FF31F94EFEE5F91F.taxon	materials_examined	Material examined. Drake Passage, Eltanin Sta. 4 - 112, 20 Jul 1962, 56.03 ° S, 61.93 ° W, 4008 m, 13 paratypes (USNM 56456); Sta. 4 - 126, 29 Jul 1962, 57.20 ° S, 62.75 ° W, 3733 – 3806 m, holotype (USNM 1013904); and 13 paratypes (USNM 56457); Sta. 4 - 155, 17 Aug 62, 56.52 ° S, 63.25 ° W 3927 m, 7 paratypes (USNM 56458); R / V Polarstern, ANDEEP I, Sta. PS- 61 / 043 - 2, 3958 m (1, SEM, JAB); PS- 61 / 046 - 3, 2888 m (1, SEM, JAB).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065D0946FF31F94EFEE5F91F.taxon	description	Description. Majority of specimens small, incomplete; holotype 5.5 mm long and 0.7 mm wide for 29 setigers; largest paratype 9.0 mm long and 0.6 mm wide for 34 setigers. A single, much larger incomplete specimen from ANDEEP I Sta. PS- 61 046 - 3 broken into two parts with 82 setigers, measuring 36 mm long and 3 mm wide across thorax. Color in alcohol: light brown. Thoracic region with 16 – 18 setigers, inflated in first 3 – 4 setigers (Fig. 33 B), subsequent thoracic setigers depressed; transition to abdominal region gradual, with last three thoracic setigers having fewer setae (Fig. 33 C). Intersegmental annulations first present from setigers 8 – 9; these weakly developed, never prominent (Fig. 33 A). Branchiae from setiger 6 (Figs. 33 A, 34 A); thoracic and anterior abdominal branchiae basally inflated (Figs. 33 A, 34 A), subsequent abdominal branchiae expanded (Fig. 33 J); branchiae absent from far posterior setigers. Prostomium triangular in outline, pointed on anterior margin (Figs. 33 A, 34 A); eyespots absent; nuchal organs in SEM as transverse slits at border of prostomium and peristomium (Fig 34 A); proboscis divided into 3 – 4 lobes (Fig. 34 A). Peristomium with one short achaetous ring (Figs. 33 A, 34 A). Thoracic notopodia with minute postsetal lamellae on setigers 1 – 2, barely seen in SEM (Fig. 33 A), becoming larger more visible from setiger 3 (Fig. 33 A), short at first, then elongating, becoming unusually long, fingerlike structures (Figs. 33 A – C, 34 A), continuing through abdominal region. Thoracic neuropodia with setae arising from elongated thickened lobes (Figs. 33 C, 34 B); postsetal lamellae from setiger 5 – 11, attached to posterior border of upper one-third of setal lobe (Figs. 33 C, 34 B); each lobe short triangular at first, then elongating in transitional region to form fingerlike lamella; a single subpodial lobe from setiger 14 – 15, continuing through anterior abdominal segments (Fig. 33 C); absent from middle and posterior abdominal segments (Fig. 33 J). Abdominal neuropodia elongated, with short ventral cirrus (Fig. 33 J). Thoracic notopodia with fascicles of numerous crenulated capillaries and a single furcate seta; abdominal notopodia with three thin crenulated capillaries, two flail setae (Fig. 33 I) and 2 – 3 furcate setae (Figs. 33 G, 34 E); furcate setae thin, delicate, easily broken, with unequal tynes connected by thin webbing composed of fine needles and shaft with faint annulations (Fig. 33 G); with SEM, furcate setae with 9 – 10 needles on each side with lateral ones merging with tynes; each tyne with minute apical opening (Fig. 34 E). Flail setae with thick, non-crenulated shaft bearing thin, crenulated tips (Fig. 33 I). Thoracic neuropodia with dense fascicles of blunt-tipped uncini arranged in four rows (Fig. 33 B – C); uncini of anterior row typically continuing ventrally below rows 2 and 3, then merging with row 4 forming a U-shape (Fig. 33 D); in some neuropodia, rows 2 and three also joined ventrally; uncini of anterior row sharply curved, with 3 – 5 transverse ridges (Fig. 33 E), with SEM ridges appearing irregular, angular (Fig. 34 C); uncini of posterior row not as sharply bent, with 9 – 10 transverse ridges (Fig. 33 F); 2 – 3 long crenulated capillaries present in superior position of last row of uncini (Fig. 33 B – C, 34 B). Abdominal neurosetae including 1 – 2 simple, blunt-tipped acicula (Figs. 33 H, 34 D) and 2 – 3 thin, simple capillaries (Fig. 33 J).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065D0946FF31F94EFEE5F91F.taxon	etymology	Etymology. hyphalos: Greek for submerged, in the deep.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065D0946FF31F94EFEE5F91F.taxon	discussion	Remarks. Of the six species of Leodamas encountered in this study, L. hyphalos n. sp. is the only one to bear flail setae in the abdominal notopodia. Leodamas hyphalos n. sp. is closest in morphology to L. marginatus in the nature and arrangement of the neuropodial uncini; both species have a few superior capillary setae dorsal to the posterior row of uncini. The thoracic neuropodial uncini of L. marginatus are arranged in three long vertical rows and with a short fourth row that continues ventral to the first three; in contrast, there are four long rows of uncini in L. hyphalos n. sp. with the first and last often merged ventrally and forming a U-shape. Although the majority of specimens were small, the much larger specimen from Sta. PS- 61 046 - 3 from lower slope depths of 2888 m was similar to L. marginatus in size. The smaller specimens of L. hyphalos n. sp. all occurred at abyssal depths greater than 3600 m, suggesting that the species may be size limited in the deeper parts of its habitat, possibly due to limited or patchy organic input to the abyssal sediments. The close similarity of L. hyphalos n. sp. to L. marginatus suggests that it may be a lower slope and abyssal sibling of the widely distributed and common shelf and upper slope species.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065D0946FF31F94EFEE5F91F.taxon	distribution	Distribution. Known only from the Drake Passage between South America and the Antarctic Peninsula; 2888 – 4008 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065E0940FF31F8DFFDBEFA7F.taxon	description	Scoloplos (Leodamas) sp. Hartman 1967: 108 (in part, Sta. 753 only).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065E0940FF31F8DFFDBEFA7F.taxon	materials_examined	Material examined. Western Chile, off Valparaiso, Eltanin Sta. 9 - 753, 26 Sep 1963, 33.27 ° S, 71.78 ° W, 192 m, holotype (USNM 1013905) and 3 paratypes (USNM 56460).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065E0940FF31F8DFFDBEFA7F.taxon	description	Description. All types incomplete, largest paratype 17 mm long, 4 mm wide for 44 setigerous segments. Thoracic region broad, dorsoventrally flattened, with 11 – 13 setigers, narrowing abruptly to more oval-shaped abdominal region. Color in alcohol: brown. Prostomium reduced, pointed on anterior margin (Fig. 35 A). Peristomium reduced, hidden by setiger 1 dorsally, reduced ventrally to simple ring around oral opening; nuchal slits present on lateral margins of peristomium; proboscis saclike. Thoracic parapodia all similar, well developed, with those of anterior segments narrowest. Segmental dorsal sense organs not present. Notopodial postsetal lamellae with broad, flattened bases tapering to narrow tips (Fig. 35 C); neuropodia consisting of broad tori bearing triangular-shaped postsetal lamellae (Fig. 35 B – C). Abdominal parapodia all similar, shifted only about 20 – 45 ° dorsally; with cirriform postsetal lamellae (Fig. 35 D). Branchiae from setiger 4; branchiae single, flattened, acuminate on anterior thoracic setigers (Fig. 35 C), becoming palmately branched from last thoracic or transitional segment of abdominal region; branchiae formed of two branches (Fig. 35 A), then increasing to three and finally four branches (Fig. 35 D); 4 - branched arrangement continuing until about setiger 40, thereafter branches reduced to 3, then 2, and 1 in far posterior segments. Notosetae including dense fascicles of long, crenulated capillaries in thoracic setigers and crenulated capillaries, furcate setae and cross-striated, non-crenulated capillaries in abdominal notopodia; furcate setae with unequal tynes between which fine needles connected in a web on both sides (Fig. 35 F). Neurosetae of thoracic setigers in 3 – 4 dense rows of uncini intermixed with few long, thin silky crenulated capillaries (Fig. 35 B – C); uncini distally curved, notched with lateral sheath and transverse ribs along shaft (Fig. 35 E); abdominal neurosetae short, non-crenulated capillaries, few in number; tip of single acicula emergent.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065E0940FF31F8DFFDBEFA7F.taxon	etymology	Etymology. Perissobranchiatus: perisso, Greek for beyond the regular number or size; branchos, Greek for gill.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065E0940FF31F8DFFDBEFA7F.taxon	discussion	Remarks. Leodamas perissobranchiatus n. sp. is most closely related to L. latum (Chamberlin, 1919), originally described from 588 m off the Pacific coast of Panama in having branched or multiple branchiae arising from a single location. The species was later reported by Fauvel (1932) from 457 m off Burma. Leodamas perissobranchiatus n. sp. differs from L. latum in having branchiae first present from setiger 4 instead of 5, in having each branchia with maximally four branches in a palmate arrangement instead of nine, and in having 11 – 13 thoracic setigers instead of 19 – 20. In addition, the branchial branches of L. perissobranchiatus arise separately, whereas in L. latum, each branch arises from a common raised core. There are also differences with the thoracic neuropodial uncini; in L. perissobranchiatus there is a lateral sheath along the shaft that is not present in L. latum. Unlike most other orbiniids, L. perissobranchiatus n. sp. has the abdominal parapodia in a more lateral position, shifted dorsally to only about 20 – 45 °, probably due to the space taken up from the bases of the additional branchiae; most dorsally oriented branchiae are present in far posterior segments. Another species of Leodamas with branched branchiae is L. cylindrifer (Ehlers, 1904) from intertidal zones in New Zealand and Australia. However, in this species the branchiae are first present from an anterior abdominal segment and are dendritically branched instead of palmate.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD065E0940FF31F8DFFDBEFA7F.taxon	distribution	Distribution. Western Chile, 192 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06580942FF31F9FFFC32FEDC.taxon	materials_examined	Material examined. Argentina, Mar del Plata, intertidal, Feb 1970, coll. J. M. Orensanz (1 juvenile, JAB); Santa Clara, mussel beds, coll. R. Elias, 12 Jan 2001, (3, MCZ 135298); Golfo San Matías, Las Chañares, intertidal, Feb 1972, Coll. J. M. Orensanz (2, USNM 1013664); South of Isla Colorado, intertidal, Jan 1973, coll. J. M. Orensanz (7, USNM 1013667); Puerto Lobos Beach, intertidal, 21 Jan 1973, coll. J. M. Orensanz (1, USNM 1013666); IBM Sta. SAO-IV- 1133, intertidal (5, 1013665). — Tierra del Fuego, Hero Sta. 71 - 2 - 8, intertidal (1, USNM 69384); Staten Island, off Tierra del Fuego, Hero Sta. 71 - 2 - 21, intertidal (1, USNM 60686). — Chile, Valparaiso Province, Viña del Mar, Montemar, next to Estacion de Biologia Marina, Universidad de Chile, 32 ° 57 ′ 25 ″ S, 71 ° 33 ′ W, sheltered beach, intertidal sand, coll. Eric Guiler, Feb 1955 (10, LACM-AHF Poly 5022); Puerto Montt, 19 Dec 2003, coll. I. Kruse, (3, SEM, JAB); Isla Santa Maria, Dec 2003, coll. I. Kruse, 1 specimen (MCZ 135297). — Straits of Magellan, Punta Arenas, in sand, Sep 1892, Coll. W. Michaelsen, syntype of Aricia tribulosa (ZMB 6767). — Peru, Punta Chira, ca. 30 km north of Camana, 9 Aug 1955, intertidal, coll. G. Hartmann, holotype of Scoloplos armiger trioculata (ZMH P- 14965).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06580942FF31F9FFFC32FEDC.taxon	description	Description. A single complete specimen from Staten Island 8 mm long, 1 mm wide for 80 setigerous segments; larger specimens from Chile up to 40 mm long, 2.5 mm wide for about 185 segments. Anterior segments dorsoventrally flattened, abdominal segments cylindrical in cross section. Thoracic region with 22 – 25 segments; Peruvian specimen with 16. Color in alcohol brown with lighter areas between segments and on prostomium. Prostomium pear-shaped, acutely pointed on anterior margin (Fig. 36 A, D) or narrowing to rounded tip (Fig. 37 A); juveniles with short, rounded prostomium; with 0 – 3 pairs of eyespots, usually only present in smallest or juvenile specimens; nuchal organs narrow vertical slits at posterior margin of prostomium (Fig. 37 A); two indistinct achaetous rings preceding first setiger on smaller specimens (Figs. 36 A, 37 A), forming smooth circular rings, ventrally forming lateral lips of mouth; larger specimens with less distinct rings, sometimes appearing to be single achaetous segment. Specimens from Montemar with multi-lobed proboscis everted (Fig. 36 D). Thoracic notopodia simple, with fascicles of long, tapering crenulated capillaries (Fig. 37 B – C); long, thin, cirriform postsetal lobe from setiger 1 (Fig. 36 A, D), gradually becoming longer and thicker in last 10 thoracic setigers. Abdominal notopodia elongated with swollen, medial expansion directed laterally (Fig. 36 E). Thoracic neuropodia expanded, with short, thick postsetal lobe from setiger 1 (Fig. 37 B – C). Abdominal notopodia with elongate postsetal lobe, thickened basally, tapering to narrow tip (Fig. 36 E). Abdominal neuropodia elongate divided apically producing short presetal lobe and elongate postsetal fingerlike lobe, between which setae emerge (Figs. 36 E, 37 I). Thoracic notosetae including 10 or more long crenulated capillaries; abdominal notosetae with five or more capillaries and 2 – 5 furcate setae; each furcate seta with two unequal blunt-tipped tynes joined by thin membranous web composed of fine needles (Fig. 37 F – G). Thoracic neurosetae including dense fascicles of uncini in 5 – 6 long vertical rows and one short posterior row and crenulated capillaries in 1 – 2 rows posterior to uncini (Fig. 37 A – C); first row of uncini longest, curving ventrally below other uncini and continuing dorsally as posterior short row (Fig. 37 B – C). Uncini strongly bent in a posterior direction, convex side of shaft with transverse rows of minute barbs or teeth, curving into dorsal groove terminating apically in two pointed teeth (Fig. 37 D), with thin hyaline sheath observed in light microscope surrounding end of uncini (Fig. 36 C), with SEM sheath a flange, extending along lateral sides of shaft to point of emergence from neuropodium (Fig. 37 D); abdominal neurosetae with 2 – 5 crenulated capillaries and 1 – 2 protruding acicular spines with curved, blunt tips (Figs. 36 E, 37 H – J). Cirriform branchiae from setiger 5 (Fig. 36 A – B). Pygidium with several large and small lobes, anal cirri absent (Fig. 36 B).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06580942FF31F9FFFC32FEDC.taxon	discussion	Remarks. Leodamas tribulosus is readily distinguished from other species by the unusual thoracic neuropodial uncini with a dorsal groove that terminates in two apical teeth and with a prominent lateral sheath. The species is common along the Chilean coast and in Patagonia where it occurs in the intertidal zone (Hartman, 1966; Hartmann- Schröder, 1962 b; 1965). The holotype of Scoloplos armiger trioculata agrees in all particulars with L. tribulosus, and is herein synonymized with this species. As part of a study of Orbiniidae phylogeny by Bleidorn et al. (2009), specimens identified as Protoariciella uncinata from Mar del Plata, Argentina were found to have the same genetic structure as Leodamas tribulosus from Chile and these authors concluded that the Argentinian specimens were juveniles of L. tribulosus. Elias et al. (2000) had earlier reported P. uncinata from Mar del Plata and noted that its morphology was variable including having a prostomium that was often pointed instead of rounded, thus further supporting the concept that juveniles of L. tribulosus have a rounded prostomium, two achaetous peristomial rings, and eyespots sometimes present. The same features are present in several of the smaller specimens examined in the present study. Three of the specimens given to C. Bleidorn were provided to me and were carefully examined; in addition to the characters mentioned, the thoracic neuropodial uncini have a distinct apical curvature, lateral sheath, and are bifid on the tips as in L. tribulosus. This does not confirm, however, that P. uncinata of Hartmann-Schröder (1962 a) is the same species and in fact, it shares characters with Naineris grubei.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06580942FF31F9FFFC32FEDC.taxon	distribution	Distribution. Peru; Chile; Argentina; Patagonia; intertidal to low water.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0644095CFF31FBB6FD03F86A.taxon	materials_examined	Material examined. Western Chile, off Chiloe Island, Eltanin Sta. 6 - 333, 27 Nov 1962, 42.93 ° S, 75.58 ° W, 3655 – 3651 m, holotype (USNM 55530).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0644095CFF31FBB6FD03F86A.taxon	discussion	Remarks. The holotype is the only known specimen of C. chilensis and is incomplete. The thorax consists of 13 setigers with branchiae from setiger 9. The species was originally differentiated from related species by the presence of three types of setae in the first three thoracic setigers: (1) crenulated capillaries, (2) short thin uncini sometimes with tips appearing bristled, and (3) larger, thicker uncini, also sometimes appearing bristled. The bristled appearance of these uncini is due to fraying of a sheath that encompasses part of the shafts best seen in SEMs of the new species, C. bilamellata described below. While the details of bristling and ribbing of these setae may be specifically unique to C. chilensis, the presence of three types of setae in setigers 1 – 3 has also been reported for C. calida Hartman, 1957 and C. schmitti (Pettibone, 1957). Capillaries are lacking in C. mexicana Fauchald, 1972. One feature overlooked by Hartman (1967), which may make C. chilensis specifically unique in the genus, is the presence of a row of shorter and thinner uncini among the numerous capillaries of setigers 4 – 5. Pettibone (1957) reported the presence of some uncini on setiger 4 in C. schmitti, but there have been no reports of such setae beyond setigers 1 – 3 in C. calida and C. mexicana. The posterior end of the holotype of C. chilensis is not well preserved and it is not clear if several fragments in the same vial belong to the holotype specimen. Nevertheless, abdominal setae may prove to be diagnostic for Califia species. Posterior notopodia of C. chilensis have a type of flail seta with a thickened shaft and finely tapered, ribbed capillary tip. Flail setae were not observed in specimens of C. schmitti collected by the author from the continental slope off the North Carolina. It would be useful to study the abdominal setae in the other species in order to determine specific differences.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0644095CFF31FBB6FD03F86A.taxon	distribution	Distribution. Off western Chile, 3651 – 3655 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0644095CFF31FF73FC23FBCA.taxon	diagnosis	Diagnosis. Prostomium pointed on anterior margin. Peristomium consisting of a single achaetous ring. Transition from thorax to abdomen abrupt due to distinct change in neuropodia. Branchiae from setiger 8 – 10; each branchia simple, lanceolate, may be lacking in most of abdominal region. Setigers 1 – 3 with dense fascicles of thickened uncini in neuropodia and 0 to few capillaries; 0 to few similar spines or uncini present in subsequent thoracic setigers, but capillaries numerous; neuropodial uncini with shafts either smooth or with ribs; tip of shaft with distinct sheath, often frayed, appearing bristled in light microscopy. Neuropodia with or without postsetal lobe; subpodial lobes absent. Abdominal segments lacking interramal and ventral cirri. Abdominal setae including capillaries, furcate setae, and flail setae; no uncini. Nature of pygidium unknown.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0644095CFF31FF73FC23FBCA.taxon	discussion	Remarks. Califia is characterized by having heavy spines or uncini in anterior thoracic neuropodia, with setigers 1 – 3 appearing visibly different from other thoracic segments. Pettibone (1957) noted that modified setae were sometimes present among the capillaries of the unmodified setiger 4 of C. schmitti (Pettibone, 1957). This same feature has been observed on setigers 4 – 5 of the holotype of C. chilensis Hartman, 1967; C. bilamellata n. sp. has some neuropodial uncini on all thoracic setigers (see below). Califia is closely related to the genus Uncorbinia described by Hartmann-Schröder (1979) from Western Australia. Uncorbinia also has thickened neuropodial spines limited to the anterior segments of the thorax. In Califia, these anterior modified segments are biramous, with the notopodia bearing large fascicles of capillaries. In Uncorbinia, segments 1 – 4 are uniramous with notopodia entirely lacking. Furthermore, the uncini of Califia appear hooded on their tips due to a distinct sheath that upon wear appears bristled due to frayed fibrils, whereas the heavy spines of setigers 1 – 4 of Uncorbinia are either simple uncini or subuluncini. Uncorbinia has a few serrated uncini among the capillaries on the biramous setiger 5. Four Califia species are presently known from slope depths, one new species described here is from continental shelf depths.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06470958FF31FF7CFB39FEDD.taxon	materials_examined	Material examined. Southern Chile, Seno Reloneavi, the Bay off Puerto Monntt, N of the light buoy NE of Isla Tengo, LUCE Sta. 4 A, 11 Sep 1948, 41 ° 28 ′ 54 ″ S, 72 ° 57 ′ 24 ″ W, 13 – 16 m, paratype (SMNH 4351); Golfo de Ancud, SW of Isla Tabon, LUCE Sta. M- 44 A, 24 Jan 1949,41 ° 58 ′ S, 73 ° 18 ′ W, ca. 200 m, holotype (SMNH 4350). — Off Uruguay, IBM Sta. N- 1073, R / V A. Knipovich, 115 – 117 m, muddy sand, 4 specimens (2, USNM 1407120), (2, SEM, JAB).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06470958FF31FF7CFB39FEDD.taxon	description	Description. All specimens incomplete; holotype 12 mm long and 1.2 mm wide for 45 setigers; paratype 6.6 mm long and 0.5 mm long for 39 setigers; largest Uruguayan specimen 15 mm long, 1 mm wide for 70 setigers. Thoracic region divided into modified anterior region consisting of three setigers with prominent neuropodial spines and few capillaries (Fig. 38 A, 39 A, C) followed by more typical region with numerous neuropodial capillaries and few spines extending to setiger 16 – 18. Color in alcohol: light tan. First three modified thoracic setigers appearing different from following setigers due to presence of enlarged neurosetae (Figs. 38 A, 39 A – C). Prostomium triangular, narrowing to pointed tip on anterior margin (Figs. 38 A, 39 C), or blunted based on preservation (Fig. 39 A); eyespots absent; nuchal organs paired transverse slits at border of prostomium and peristomium (Fig. 39 A) proboscis a soft sac, partially everted on paratype. Peristomium not annulated, completely fused with prostomium (Figs. 38 A, 39 A). Thoracic notopodial lamellae fingerlike from setiger 1 (Fig. 38 A), short at first becoming longer and more prominent from setiger 4 – 5; neuropodia of Chilean specimens with single postsetal lamella from setiger 4, continuing to setiger 9, then second neuropodial lamella from setiger 10 – 12 (Fig. 38 A), continuing to setiger 16 – 18, then second one lost; Uruguayan specimens with second neuropodial lamella only on last 2 – 3 thoracic setigers; a single subpodial lamella present through first 3 – 6 anterior abdominal segments (Fig. 38 F). Abdominal parapodia all similar, with long, thin notopodial lobe and divided neuropodial lobe (Fig. 38 F); no interramal cirrus. Thoracic notopodia with simple fascicle of crenulated capillaries; abdominal notopodia with anterior ventral fascicle of 3 – 4 thick crenulated capillaries and a dorsal fascicle of 10 – 12 thinner crenulated capillaries, and 1 – 2 furcate setae (Fig. 38 F). Furcate setae with unequal tynes connected by 3 – 4 thin needles on each side, merging and fused with tynes; tips of tynes with distinct openings (Fig. 39 G – H); shafts generally smooth except for few minute barbs, but no transverse ridges. Thoracic neuropodia with three types of setae: (1) an anterior row of short, narrow, prominently crenulated blunt-tipped uncini having a notched tip and hyaline hood or sheath (Fig. 38 B, D – E); (2) heavy uncini on setigers 1 – 3 in second and third row with a smooth shaft and pointed to worn tip, sometimes with remnants of hyaline hood or with hood worn to frayed fibril endings or entirely absent (Fig. 38 B – C), with SEM sheath sometimes frayed on tip, extending posteriorly along shaft to where weak transverse ribs apparent (Fig. 39 B, E); (3) crenulated capillaries. Narrow uncini (1) present in all thoracic setigers, numbering 5 – 6 throughout, representing anterior row of uncini in setigers 1 – 3, then shifted ventrolateral in setigers 4 – 18 and surrounded by several rows of capillaries (Fig. 39 F); heavy uncini (2) limited to second and third rows in setigers 1 – 3 numbering 4 – 5 per row (Figs. 38 B, 39 B, D); capillaries limited to small dorsally located fascicle in setigers 1 – 3, then in dense fascicles of 4 – 6 rows in setigers 4 – 18. Abdominal neuropodia with 2 – 3 narrow aciculae, barely emergent and 4 – 5 thin, weakly barbed to smooth capillaries (Fig. 38 F). Branchiae from setiger 9 – 10 (Fig. 38 A), short, conical at first, becoming very broad at base, then triangular in middle of thoracic region; anterior abdominal branchiae short, triangular (Fig. 38 F), becoming long, narrow in posterior segments. Pygidium unknown.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06470958FF31FF7CFB39FEDD.taxon	etymology	Etymology. The specific name, bilamellata, is Latin (bi for two; lamella for plate) and refers to the double neuropodial lamellae of the posterior thoracic segments.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06470958FF31FF7CFB39FEDD.taxon	discussion	Remarks. Califia bilamellata n. sp. is the first species of the genus to be collected from continental shelf depths; all previously described species have been recorded from slope and abyssal depths. Califia bilamellata n. sp. differs from all other species of the genus in having one type of narrow uncini present in all of the thoracic setigers in addition to the typical heavy modified uncini of setigers 1 – 3. The narrow uncini occur in the anterior row in setigers 1 – 3 and in a more ventral location in following thoracic setigers. In other species, the narrower uncini may occur in setigers 4 – 5, but never over the entire thoracic region (see discussion for C. chilensis above). By having two distinct types of uncini, the smaller of which is present throughout the thoracic region with capillaries, this species shares generic characters with species of Scoloplos and may represent a transitional species between the two genera. In addition, C. bilamellata n. sp. is unique among species of Califia in having two thoracic neuropodial lamellae in posterior thoracic setigers and in having an additional subpodial lobe in some anterior abdominal setigers. The Chilean and Uruguayan specimens appear to represent the same species with the only apparent difference being that the paired postsetal lamellae of thoracic neuropodia are distributed over 10 or more setigers in the former and restricted to the last 2 – 3 setigers in the latter. However, only six specimens of this species have been collected to date and variation is not well documented.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06470958FF31FF7CFB39FEDD.taxon	distribution	Distribution. Chile, 13 – 200 m in fine to coarse sand; off Uruguay, 115 – 117 m in muddy sand.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06400958FF31FE9BFB72FBE3.taxon	diagnosis	Diagnosis. Prostomium conical, pointed; peristomium with 1 achaetous ring. Branchiae from thoracic setigers (5 – 20). Posterior thoracic segments with postsetal lobes (2 – many) and subpodial lobes (3 – many), usually forming ventral encircling fringe of 5 or more lobes. Thoracic neurosetae including blunt uncini, crenulated capillaries and rarely subuluncini; heavy spear-like or brush-tipped spines absent. Abdominal neuropodia with flail setae.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06400958FF31FE9BFB72FBE3.taxon	discussion	Remarks. Species having a modified posterior thoracic region with spearlike spines are referred to the genus Phylo Kinberg in accordance with Hartman (1957) and Day (1973). Species of Phylo are, however, closely related to Orbinia species in overall morphology and are often treated as a subgenus of Orbinia. Results of recent molecular analyses (Bleidorn 2005; Bleidorn et al. 2009) confirm these findings. To date, 20 species and subspecies of Orbinia sensu stricto are known with two new species recently described from offshore Brazil (Leão & Santos 2016). Most have branchiae from setiger 5 – 7, while a small group of three species have branchiae from setiger 8 or more posteriorly. A fourth species, belonging to the latter group has been discovered from intertidal sand sediments in Argentina. A single specimen of a species with branchiae from setiger 6 has been found in the South Shetland Islands on the Antarctic Peninsula and may represent another undescribed species. This specimen is described, but not named here due to the lack of sufficient material.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06400955FF31FB9DFCD4FC40.taxon	materials_examined	Material examined. Argentina, intertidal, sand beaches, coll., J. M. Orensanz: Golfo San Matías, Las Grutas, 14 Jan 1973, 4 paratypes (USNM 1013910); Golfo Nuevo, Golfo San José, San Ramon, 17 Nov 1975, holotype and 2 p aratypes (USNM 1013908 – 9); 17 Feb 1975, 2 paratypes (USNM 1013911).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06400955FF31FB9DFCD4FC40.taxon	description	Description. All specimens posteriorly incomplete; holotype from San Ramon 10 mm long, 1 mm wide for 60 setigerous segments; paratypes from Las Grutas larger, up to 30 mm long, 1.2 mm wide for 95 setigerous segments. Body depressed in thoracic region; abdominal segments cylindrical. Thorax with 17 – 24 setigerous segments, with largest specimens having more thoracic setigers; at least 1 – 2 segments transitional. Color in alcohol: light brown, with white-colored sub-neuropodial abdominal flanges. Prostomium conical, acutely pointed on anterior margin (Fig. 40 A); no eyespots; nuchal organs not observed. Peristomium reduced, fused to setiger 1; proboscis with 3 – 4 lobes. Thoracic setigers all similar. Thoracic notopodia with postsetal lobes from setiger 4 – 5, lobes short at first, becoming cirriform in middle and posterior thoracic segments (Fig. 40 A, C – D), continuing on following abdominal setigers (Fig. 40 E – F). Largest specimens with distinct interramal cirrus in posterior thoracic setigers, first present from about setiger 18 – 19 (Fig. 40 D); interramal cirrus absent in abdominal segments. Thoracic neuropodia reduced to low thickened ridge from which setae emerge (Fig. 40 B – C); postsetal lobes present from medial posterior edge of setiger 3 – 4, short at first, becoming larger, triangular-shaped cirri by setiger 10 – 11 (Fig. 40 C); last 1 – 4 thoracic setigers with two postsetal lobes and 1 – 9 subpodial lobes on each side, forming distinct ventral fringe (Fig. 40 B, D) continuing through 3 – 7 abdominal setigers (Fig. 40 B); all subpodial lobes cirriform, expanded basally; numbers of segments with subpodial lobes dependent upon size, larger specimens with more. Abdominal parapodia elevated dorsally on large fleshy parapodial cushion (Fig. 40 E); neuropodia bilobed with inner lobe or dorsal cirrus shorter; outer lobe or ventral cirrus longer (Fig. 40 E – F); fleshy subpodial flanges present, with medial notch (Fig. 40 E – F). Thoracic notosetae all crenulated capillaries (Fig. 41 D); abdominal notosetae including crenulated capillaries (Fig. 40 L) and furcate setae (Fig. 40 J); furcate setae with bifid-tipped unequal tynes connected by thin webbing composed of very fine needles (Fig. 40 J), with SEM individual needles tapering to fine tip, tips of tynes flattened, with distinct opening (Fig. 41 E); shaft smooth, transverse rows of barbs not apparent. Thoracic neurosetae with 4 – 5 more or less vertical rows of uncini (Figs. 40 B, 41 A – B); with companion crenulated capillaries in superior position of last row (Figs. 40 B – D, 41 A – B), some posterior thoracic setigers with a few additional capillaries in middle of neuropodium (Figs. 40 D, 41 B); uncini of setigers 1 – 4 thinner, more delicate than those on following thoracic setigers, where thick, heavy uncini in superior locations grade ventrally to thinner ones (Figs. 40 B – C, 41 A); thickest uncini with blunted tip, curved convex side flattened, then grading into 3 – 4 prominent transverse ribs on convex curvature, rest of shaft smooth; ribs most prominent on anteriormost uncini (Figs. 40 G – H, 41 A – C), thin uncini smooth or with transverse ribs weakly developed (Fig. 40 I). Abdominal neurosetae include 3 – 4 flail setae (Fig. 40 K), a thin, imbedded acicula, and an occasional delicate, smooth capillary seta; flail setae with thickened shaft bearing delicate ribs and very thin, smooth, terminal extension piece (Fig. 40 K). Branchiae from setiger 13 – 18, each elongated, expanded basally (Figs. 40 C, E – F).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06400955FF31FB9DFCD4FC40.taxon	etymology	Etymology. This species is named for the late Dr. José M. (Lobo) Orensanz, who generously allowed me to study his collections of Orbiniidae from Argentina and Uruguay, and who made significant contributions to the study of the polychaetes of Argentina and the Southern Ocean.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06400955FF31FB9DFCD4FC40.taxon	discussion	Remarks. Orbinia orensanzi n. sp. belongs to a small group of species having branchiae from segments posterior to setigers 5 – 6, including O. hartmanae Day, 1977 from eastern Australia, O. riseri (Pettibone, 1957) from eastern North America and O. johnsoni (Moore, 1909) from western North America. Of these, only O. riseri and O. orensanzi n. sp. have interramal cirri. In O. riseri, the interramal cirrus is present in abdominal parapodia, whereas in O. orensanzi n. sp. they are present only in thoracic parapodia. A distinct ventral cirrus, present in O. riseri, is lacking in O. orensanzi n. sp. Thoracic neuropodial uncini are all smooth in O. hartmanae, ribbed and smooth in O. orensanzi n. sp., and ribbed with hoods in O. riseri and O. johnsoni.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06400955FF31FB9DFCD4FC40.taxon	distribution	Distribution. Argentina, intertidal in sand beaches.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064D0955FF31FC22FC14F82F.taxon	materials_examined	Material examined. Antarctic Peninsula South Shetland Islands, Eltanin Sta. 6 - 437, 267 – 311 m (1, LACM-AHF Poly 4994).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064D0955FF31FC22FC14F82F.taxon	description	Description. A single specimen included among USNS Eltanin collections from Eltanin Station 437 and identified by Dr. Olga Hartman, as Phylo kupfferi is here referred to the genus Orbinia because posterior thoracic modified notosetae are not present. Other specimens in the same sample are referred to Phylo felix (see below). Specimen mostly complete, 0.8 mm wide across anterior thoracic region, 7 mm long for 35 setigerous segments. Color light tan in alcohol with no pigmentation. Anterior end of body swollen through setiger 5. Thoracic region with 12 setigers; no posterior modified thoracic segments. Prostomium short, triangular, pointed on anterior margin; nuchal organs not observed. Peristomium short and narrow. Branchiae from setiger 6. Pygidium unknown. Thoracic notopodia short with inconspicuous cirriform lobes on setigers 1 – 5; with the branchiae they become long and prominent on setiger 6, continuing posteriorly. Thoracic neuropodia with a single postsetal lobe through setiger 6, increasing to 3 – 4 from setiger 7, becoming continuous with subpodial ventral fringe on setiger 11; ventral fringe continuing posteriorly to abdominal setiger 16. Abdominal notopodia with elongate dorsal cirrus; abdominal neuropodia flattened, rounded apically, with distinct ventral cirrus. Interramal cirri not present. Thoracic notosetae long, camerated capillaries arranged in two rows; thoracic neurosetae with three rows of heavy, curved uncini and a posterior row of heavy camerated capillaries. Individual uncini with smooth curved tip followed by transverse ribs further down shaft; with light microscopy, evidence of sheath on side opposite transverse ribs. Abdominal notosetae consisting of 3 – 4 long, narrow camerated capillaries and 2 – 3 delicate furcate setae; furcate setae with unequal tynes with thin webbing between. Abdominal neurosetae with 1 – 2 aciculae, sometimes emergent, with curved blunted tips and 2 – 4 long, thin, simple capillaries.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064D0955FF31FC22FC14F82F.taxon	discussion	Remarks. This specimen was among a small collection from Eltanin Sta. 437 identified by Hartman (1966) as Phylo kupfferi, here referred to P. felix (see below); this single specimen is the only representative of the genus Orbinia reported to date from Antarctica and may represent an undescribed species, but due its incomplete nature and small size, it cannot be named at this time.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064D0955FF31FC22FC14F82F.taxon	distribution	Distribution. Antarctic Peninsula, South Shetland Islands, 267 – 311.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064C0954FF31FF73FABFFCF1.taxon	diagnosis	Diagnosis. Prostomium pointed on anterior margin; peristomium with one achaetous ring. Branchiae first present from setiger 5 – 7. Posterior thoracic segments with several postsetal lobes and subpodial lobes (at least five of each type) together usually forming ventral fringe. Thoracic neurosetae including blunt uncini and crenulated capillaries; posterior thoracic segments with modified spearlike spines. Flail setae present or absent in posterior abdominal notopodia.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064C0954FF31FF73FABFFCF1.taxon	discussion	Remarks. Species of Phylo are closely related to species of Orbinia and differ chiefly in having the thoracic region divided into anterior and posterior regions; the posterior region bears modified spines. Phylogenetically, the modified thoracic spines are apomorphic rather than plesiomorphic but provide species of Phylo with an obvious and practical distinctness that makes them easy to identify. Because of this character, Phylo is retained as a genus, although subgeneric rank with Orbinia might be preferred by some investigators. Ten species of Phylo were reviewed by Hartman (1957), who provided detailed descriptions for three, including the type species, P. felix Kinberg. Additional species have been described by Day (1961; 1977), Wu (1962), Mohammad (1970), and Hartmann-Schröder & Rosenfeld (1990). Phylo felix was encountered in the present study and appears to be limited to South America and the Antarctic Peninsula. Orbinia (Phylo) minima described from the Antarctic Peninsula by Hartmann-Schröder & Rosenfeldt (1990) is represented only by small specimens but agrees well with P. felix.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064C0951FF31FC6EFBF1F817.taxon	materials_examined	Material examined. Uruguay: IBM Sta. N- 242, 63 m in sand (2, USNM 1013676); IBM Sta. N- 250, 83 m (7, USNM 1013677); IBM Sta. N- 1066, 72 – 86 m (1, USNM 1013678); IBM Sta. N- 1073, 115 – 117 m (1, JAB). — Argentina, offshore, R / V Vema Sta. V- 18 - 12, continental slope E of Deseado, 424 – 428 m (2, LACM-AHF Poly 5036, 5044); V- 17 - 101, E of Mar del Plata, benthic trawl, 19 Jun 1961 (4, LACM-AHF Poly 5041). — Argentina, nearshore, San Antonio Bay, intertidal, 1 Jan 1973, coll. J. M. Orensanz (1, USNM 1013684); Marajada norte, high intertidal, 8 Feb 1971, coll. Panetta (5, USNM 1013685); Riacho Jabali, San Blas Bay, 4 Oct 1968, intertidal, muddy sand flats, coll. J. M. Orensanz (4, USNM 1013682); Mar del Plata, mussel bed, 19 Aug 1970, coll. J. M. Orensanz (1, USNM 1013683); Golfo San Matías, low intertidal, in gravel, IBM Sta. SAO-III- 1 0 41 (1, USNM 1013680); IBM Sta. SAO-III- 1048, intertidal (1, USNM 1013679); IBM Sta. N- 1054, 58 – 65 m, (1, USNM 1013675); IBM Sta. N- 1059, 80 – 72 m (1, USNM 1013674); IBM Sta. N- 1073, 115 – 117 m, (1, USNM 1407118); IBM Sta. N- 1074, 112 m (1, USNM 1013673); IBM Sta. N- 1075, 68 m (2, USNM 1013672; 1, USNM 1407117); Tierra del Fuego, Hero Sta. 651, 40 m (1, USNM 60642); Staten Island, Hero Sta. 659, intertidal (1, USNM 60643); Hero Sta. 665, 44 m (4, USNM 60644). — Falkland Islands, Teal Inlet, 2 Apr 1927, intertidal, coll. W. L. Schmidt (1, USNM 24431). — SE of Falkland Islands, R / V Vema Sta. M- 14 - 12, 361 m (1, LACM-AHF Poly 5029). — Chile, Golfo de Quetalmahué, Isla Pullinque, N of Punta Ranqui, LUCE Sta. M- 8 B, Intertidal in mud (1, SMNH 154448); Golfo de Ancud, SW of Isla Tabon, LUCE Sta. M- 44, ca. 200 m, fine sand mixed with clay (1, SMNH 154446); Seno Reloneavi, Isla Tenglo, the bay on the South Side, LUCE Sta. M- 60 intertidal in sand (15, SMNH 154435); Seno Reloneavi, Piedra Azul, NW of Punta Quillaipe, LUCE Sta. M- 16 E, 30 m (5, SMNH 154445); Golfo Coreovado, Baja Vettor Pisani, LUCE Sta. 65 A, 8 m, (1, SMNH 154443); Seno Reloneavi, E of Isla Guar, LUCE Stas. M- 144, ca. 250 m, (1, SMNH 154436); same data, Sta. M- 144 A (1, SMNH 154439); Seno Reloneavi, Bahía Chincui, LUCE Sta. M- 145, 70 – 80 m, (4, SMNH 154438); SW of Valdivia, 39 ° 59.9 ′ S; 74 ° 01.5 ′ W, 15 Mar 1960, 260 m, dredged, holotype of Phylo felix heterosetosa (ZMH P- 14871). — Straits of Magellan, Punta Arenas, in sand, coll. Sep 1892, W. Michaelsen, syntype of Aricia michaelseni (ZMB 6764); Voillier Cove, 54 ° 53 ′ S, 69 ° 38 ′ W, 3 Feb 1896, 18 m, in sand, coll. E. Nordenskold (2, SMNH 1398); Puerto Tor, 55 ° 67 ′ S, 67 ° 06 ′ W, 11 Feb 1896, 36 – 46 m, shell bottom with rocks, coll. E. Nordenskold (1, SMNH 1399); Puerto Eugenia, 54 ° 56 ′ S, 67 ° 43 ′ W, 12 Feb 1896, 18 – 27 m, rocks with algae, coll. E. Nordenskold (2, SMNH 1400). — Antarctic Peninsula, Bismarck Strait, Hero Sta. 970, 102 m (1, USNM 60645); Bransfield Strait, Eltanin Sta. 6 - 410, 220 – 240 m (1, USNM 56452); South Shetland Islands, Eltanin Sta. 6 - 437, 267 – 311 m (3, USNM 56453). — Off Elephant Island, R / V Walther Herwig Sta. 148, 61 ° 12.7 ′ S, 55 ° 56.4 ′ W, 134 m, holotype and 14 paratypes (ZMH 19930 - 1) of Orbinia (Phylo) minima.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064C0951FF31FC6EFBF1F817.taxon	description	Description. A large species, one complete Chilean specimen 80 mm long, 2.9 mm wide, for 240 setigers; incomplete specimens larger, up to 92 mm long. Anterior fragments of 3.5 mm wide suggesting even larger specimens; Hartman (1948) recorded one of Kinberg’s fragmented specimens at 5 mm wide. Thorax with 15 – 19 setigerous segments; (1) anterior thoracic region with 10 – 12 setigers; (2) posterior region with 5 – 8 setigers. Prostomium triangular, narrow, pointed on anterior margin depending upon preservation (Figs. 42 A, 43 A – B), peristomium a narrow asetigerous segment, smaller than setiger 1 (Figs. 42 A, 43 A – B); eyespots absent; nuchal organs narrow paired slits at border of prostomium and peristomium (Fig. 43 B). Thoracic notopodia, with elongate, fingerlike postsetal lamellae continuing through abdominal segments (Figs. 42 A, 43 B). Interramal cirrus present between noto- and neuropodia of posterior thoracic segments, continuing over most abdominal segments (Fig. 42 C). Thoracic neuropodia with 2 – 3 postsetal lamellae from setiger 1, increasing to 9 – 12 over middle and posterior thoracic setigers (Figs. 42 A, 43 E); ventral fringe of numerous subpodial lobes or stomach papillae from setiger 11 – 14 (Figs. 42 A, 43 F), these beginning as 1 – 3 lobes increasing to 25 or more, nearly encircling ventral side of worm, abruptly absent from setiger 17 – 20, depending upon size of worms; abdominal neuropodia expanded apically, divided into two lobes; with a single ventral cirrus (Fig. 42 C). Thoracic notosetae including dense fascicles of crenulated capillaries and imbedded aciculae; abdominal notosetae including long, thin capillaries and 3 – 4 furcate setae; furcate setae with unequal tynes connected by a web of numerous fine needles; tips of tynes blunted, shaft with transverse rows of barbs (Fig. 42 G). Thoracic neuropodia of setigers 1 – 10, with 4 – 6 rows of uncini of two types: (1) 3 – 5 rows of large, heavy uncini, each with curved apex surrounded by long sheath and followed by shaft with transverse ridges; sheath sometime frayed, appearing bristled (Figs. 42 D, 43 C – D), (2) a posterior row of narrower crenulated spines (Fig. 42 E); posterior row of numerous crenulated companion capillary setae accompany uncini; from about setiger 11 – 12, uncini of posterior thoracic neuropodia mostly replaced by large, dark, spear-like spines (Figs. 42 B, F, 43 E) accompanied by numerous long, crenulated capillaries (Fig. 43 E). Abdominal neurosetae including 5 – 6 short capillaries and 1 – 2 imbedded aciculae (Fig. 42 C). Branchiae from setiger 4 – 5 (Figs. 42 A, 43 B), simple, with lateral and medial cilia, continuing posteriorly (Fig. 42 C). Pygidium enlarged, swollen, turned dorsally, with two ventral rounded lobes and two dorsal lobes from which a pair of long anal cirri arise; anus located dorsally between all four lobes (Fig. 42 H).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064C0951FF31FC6EFBF1F817.taxon	discussion	Remarks. Phylo felix was thoroughly reviewed, accurately described, and elegantly illustrated by Hartman (1957). The present specimens agree well with her description, although the large collection of specimens permits additional details to be added. In particular, the distribution of thoracic neurosetae is more complex in that there are many more capillaries accompanying the uncini than previously reported.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064C0951FF31FC6EFBF1F817.taxon	description	The holotype of Phylo felix heterosetosa from Chile described by Hartmann-Schröder (1965), has been examined and not found to differ from the stem form. The subspecies is therefore synonymized with P. felix in this study.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064C0951FF31FC6EFBF1F817.taxon	distribution	Distribution. South America: Brazil, Uruguay, Argentina, Patagonia, Southern Chile, Straits of Magellan; Falkland Islands; Antarctic Peninsula and off Elephant Island, Intertidal to 430 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06480953FF31FF57FCDBFE48.taxon	diagnosis	Diagnosis. Prostomium rounded or truncate on anterior margin. Peristomium with 1 – 2 achaetous rings. Thorax with 12 – 30 or more segments; branchiae first present from setiger 2 – 23. Thoracic neuropodia with 0 – 2 postsetal lobes; no subpodial lobes. Thoracic neurosetae including capillaries, or capillaries mixed with blunt-tipped uncini, sometimes hooded, or uncini and subuluncini. Abdominal setae including capillaries and sometimes furcate setae in notopodia and capillaries and imbedded or protruding aciculae in neuropodia. Paired dorsal sensory organs present in some species.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06480953FF31FF57FCDBFE48.taxon	discussion	Remarks. The following six species of Naineris were encountered and are treated in this paper:	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06480953FF31FF57FCDBFE48.taxon	description	N. antarctica, n. sp. The holotype vial of N. brevicephala Hartmann-Schröder, 1960 from Peru was examined and found to contain a syllid. Until the actual type specimen is located, N. brevicephala is best treated as incertae sedis.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06480953FF31FF57FCDBFE48.taxon	discussion	Remarks on the genus Protoariciella Hartmann-Schröder, 1962 a. Protoariciella was established for a small orbiniid that had two peristomial rings, and no distinct body regions, but has neuropodial uncini on a defined number of anterior setigers. The genus currently includes five species: P. uncinata Hartmann-Schröder, 1962 a, the type species, from Peru and northern Chile; P. heteroseta Hartmann-Schröder, 1962 b from northern Chile; P. parauncinata Hartmann-Schröder, 1965 from northern Chile; P. subuluncinata Hartmann-Schröder, 1974 from West Africa; and P. oligobranchia Hobson, 1976 from British Columbia. The genus appears to be confused because the type species, P. uncinata, was also reported to have thickened notopodial setae in the posteriormost segments (Hartmann-Schröder, 1962 a: 134; 1965: 131, fig. 156). None of the other four species are reported to have such setae in abdominal notopodia, yet this character was included in the original generic definition (Hartmann- Schröder, 1962 a: 133) and was used by Rullier (1972) and Fauchald (1977) to define and distinguish Protoariciella from related genera. Apart from a record of P. uncinata from Argentina by Elias et al. (2000), there have been few reports of any Protoariciella species in recent years. However, as part of a recent molecular analysis of some Orbiniidae by Bleidorn et al. (2009), specimens from Argentina collected by R. Elias and identified as P. uncinata were included in the analysis and were found to have the same genetic structure as Leodamas tribulosus from Chile. Some of Elias’s specimens were sent to me for examination in this study and the modified spines were clearly identical to those of L. tribulosus (see above). These are thus juveniles of L. tribulosus and were treated as such by Bleidorn et al. (2009). However, this does not demonstrate that P. uncinata of Hartmann-Schröder (1962 a) is the same species. To add to the confusion, Naineris antarctica n. sp. has two peristomial rings, but otherwise differs considerably from all of the previously described species of Protoariciella, found in the Antarctic collections. This new species has heavy spines in all abdominal notopodia (see below), but also has a distinct thorax and abdomen. Given the small size of the various species of Protoariciella (all less than 10 mm) described thus far and the fact that two achaetous peristomial segments are characteristic of larval and postlarval stages of different species of Naineris and Leodamas tribulosus, it seems likely that the five species of Protoariciella are all juveniles of other orbiniids. There is no information to indicate that any of Hartmann-Schröder’s specimens were sexually mature. Apart from the double nature of the peristomial rings, the new Antarctic species agrees with the definition of Naineris to which it is here assigned. Assuming that Protoariciella species are indeed juveniles of other larger species, then the genus would be a synonym of either Leodamas or Naineris depending on the placement of the type-species P. uncinata. Both P. uncinata and P. parauncinata have bifid neuropodial uncini and may be juveniles of N. grubei or possibly L. tribulosus, whereas P. heteroseta, with neuropodial uncini that have entire tips might be a juvenile of N. chilensis. Apart from the specimens identified as P. uncinata by Elias et al. (2000) from Argentina and demonstrated to be juveniles of L. tribulosus, no adult specimens resembling the three South American species of Protoariciella were encountered in the present study.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064B0953FF31FE3AFA41F847.taxon	materials_examined	Material examined. Galápagos Islands, Isla Santa Cruz, Puerto Nunez, intertidal in rocks, Anton Bruun Cruise 12, Sta. 66 - 120 (1, USNM 60628).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064B0953FF31FE3AFA41F847.taxon	description	Description. Galápagos Island specimen incomplete, lacking pygidium and last few posterior setigers; 50 mm long and 3 mm wide for 160 setigers. Color in alcohol: light tan. Prostomium short, blunt, slightly rounded on anterior margin (Fig. 44 A); eyespots arranged in two groups of small pigment spots; everted proboscis large, saclike, multilobed (Fig. 44 A). Peristomium a single achaetous ring appearing irregular in shape, fused dorsally to posterior margin of prostomium (Fig. 44 A). Branchiae from setiger 5, continuing to posterior end; each branchia short at first, flattened, cirriform, tapering to pointed tip (Fig. 44 B); branchiae increasing in length, with those of posterior abdominal segments longest and least erect. Paired dorsal sensory organs anterior and medial to branchial bases of anterior segments. Low dorsal crests present between anterior abdominal branchiae. Thoracic notopodia broad, triangular, tapering to narrow tip (Fig. 44 B); abdominal notopodia digitiform, with blunted tip (Fig. 44 C). Posterior thoracic setigers with interramal swelling between neuropodia and notopodia (Fig. 44 B); distinct interramal cirrus lacking in thoracic and abdominal regions. Thoracic neuropodia elongate, thickened lobes, with posterior margin forming postsetal lobe, dorsally pointed (Fig. 44 B); abdominal neuropodia reduced to short, blunted postsetal lobe (Fig. 44); ventral cirri lacking. Thoracic neurosetae including dense fascicles of hundreds of capillaries arranged in 6 – 7 rows; capillaries of anteriormost row shorter, thicker, more strongly bent than those of subsequent rows; each capillary with minute teeth arranged in transverse rows on shaft (Fig. 44 F); thoracic uncini absent. Abdominal neuropodia with few capillaries and 2 – 3 smooth, curved aciculae with narrow tip (Fig. 44 D). Thoracic notopodia with 30 – 40 long, thin capillaries similar in structure to neurosetae; abdominal notosetae including capillaries and 1 – 2 furcate setae; each furcate seta with unequal tynes connected by webbing composed of fine needles; shaft with transverse rows of minute barbs (Fig. 44 E).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064B0953FF31FE3AFA41F847.taxon	discussion	Remarks. A more detailed description of Naineris setosa together with a review of its biology and ecology was presented by Blake & Giangrande (2011) who reported on an invasive occurrence of the species from a fish aquaculture facility in Brindisi, Italy. Naineris setosa is well-known from tropical and subtropical habitats in Bermuda, Florida and Gulf of Mexico, the Caribbean, and most recently from the Pacific coast of Costa Rica and Mexico (Blake & Giangrande 2011; Dean & Blake 2015). The specimen reported here from the Galápagos Islands agrees very well with those from reported from the North American locations and thus the range extends well out into the Pacific.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD064B0953FF31FE3AFA41F847.taxon	distribution	Distribution. Atlantic Ocean, Bermuda; Florida; Mexico, Vera Cruz; Puerto Rico, Belize; eastern Pacific, Mexico, Acapulco, Costa Rica, Cocos Islands, Galápagos Islands; invasive in the Adriatic and Mediterranean Seas.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0675096CFF31FF7CFB91FBCF.taxon	materials_examined	Material examined. Argentina, Staten Island off Tierra del Fuego, Hero Cruise 712, Sta. 664 (1, USNM 60639). — Strait of Magellan, Eltanin Cruise 11, Sta. 960 (1, USNM 60638).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0675096CFF31FF7CFB91FBCF.taxon	description	Description. Both specimens posteriorly incomplete, with largest (USNM 60639) 23 mm long, 2 mm wide for 64 setigers. Color in alcohol: light tan to brown. Prostomium blunt, with slightly rounded frontal margin (Fig. 45 A); no eyespots; peristomium a simple achaetous ring, ventrally forming lips of mouth; proboscis partially everted, appearing dendritic. Thoracic region with 17 – 19 setigers, appearing dorsally compressed; 1 – 2 transitional segments present between thorax and abdomen; abdominal region cylindrical. Branchiae from setiger 4, continuing to posterior end; each branchia flattened, cirriform, tapering to pointed tip (Fig. 45 F – G), ciliated on inner margins; branchiae of posterior segments flatter and broader (Fig. 45 H). Thoracic notopodial postsetal lobe elongate, thin, and fingerlike, with forked tips by setiger 17 – 18 (Fig. 45 G); subsequent notopodial lobes and those of posterior segments forked (Fig. 45 H) or undivided; occurrence of forked notopodial lobes irregular from segment to segment; interramal cirrus absent. Thoracic neuropodia slightly thickened, with short, fingerlike postsetal lobe from setiger 1 (Fig. 45 F); abdominal neuropodia divided into two apical lobes, between which setae emerge (Fig. 45 H). Thoracic notopodia with 30 – 40 long, crenulated capillaries and 3 – 5 furcate setae; abdominal notopodia with few capillaries and furcate setae; each furcate seta with unequal tynes having blunted, bifid tips; tynes connected by a thin membrane composed of very fine needles, shafts with transverse ribs (Fig. 45 E). Thoracic neuropodia with dense fascicles of uncini (Fig. 45 B) and crenulated capillaries (Fig. 45 C); each uncinus with transverse ribs; abdominal neurosetae reduced to a few crenulated capillaries and 1 – 2 smooth, slightly curved aciculae (Fig. 45 D).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0675096CFF31FF7CFB91FBCF.taxon	etymology	Etymology. furcillata: Latin for forked.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0675096CFF31FF7CFB91FBCF.taxon	discussion	Remarks. Naineris chilensis Carrasco, 1977 is a junior homonym of N. dendritica chilensis Hartmann- Schröder, 1965 and is herein renamed N. furcillata. The specimens described here are considered to represent the same species as Carrasco’s material from western Chile. The type specimens of Carrasco’s species were requested but were not provided. Naineris furcillata is unique in the genus in having the posterior thoracic and abdominal notopodial postsetal lobes and abdominal neuropodia with bifid or forked tips. The occurrence of forked or undivided lobes in the notopodia is variable from segment to segment, but consistent in the neuropodia; Carrasco’s holotype is depicted as having only the neuropodial lobes forked.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0675096CFF31FF7CFB91FBCF.taxon	distribution	Distribution. Argentina, Patagonian region; Chile, Strait of Magellan; 10 – 64 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06740969FF31FBB2FD20FEFF.taxon	materials_examined	Material examined. Ecuador, Anton Bruun Sta. 66 - 70 (1, USNM 60641), 8 – 9 m; 3 juveniles (USNM 60637). — Peru, South of Callao, Anton Bruun Sta. 65 - 215, shallow subtidal (USNM 60640). — Chile, Arica Province, Aricia, 18 ° 29 ′ 33 ″ S, 70 ° 19 ′ 17 ″ W, intertidal shale, coll. Eric Guiler, Papudo Corvette sta. N 17, 26 – 28 Feb 1955 (1, LACM- AHF Poly 5021); Chile, Puerto Aguirre, coll. 21 Jul 1958, 10 m, holotype of Naineris dendritica chilensis (ZMH- P- 15326).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06740969FF31FBB2FD20FEFF.taxon	description	Description. A large species, Chilean specimen [Holotype of N. dendritica chilensis] from Puerto Aguirre 60 mm long, 6 mm wide for approximately 250 setigerous segments. Body broad, depressed in thoracic region, cylindrical in abdominal region. Thorax with 15 – 30 setigers, depending upon size: larger specimens with more thoracic setigers. Branchiae from setiger 7 – 8, continuing to posterior end. Prostomium broadly rounded on anterior margin (Figs. 46 A, 47 A); no eyespots; no nuchal organs observed. Peristomium a single narrow folded achaetous ring (Figs. 46 A, 47 A); proboscis large, multilobed (Fig. 46 A). Thoracic notopodial postsetal lamellae broadly triangular (Fig. 46 B); abdominal notopodial postsetal lamellae similar, but not as broad and elongated (Fig. 46 C). Thoracic neuropodial postsetal lobes foliaceous ridges with uppermost edge prolonged (Fig. 46 B); abdominal neuropodial postsetal lobes lower, less foliaceous (Fig. 46 C). Thoracic notosetae all crenulated capillaries; abdominal notosetae including capillaries, 2 – 3 furcate setae and 5 – 6 deeply imbedded aciculae; furcate setae with unequal tynes, longest blunt on tip, shortest thin, pointed, with about 10 thin needles between tynes (Fig. 47 D); shaft with numerous crowded transverse rows of barbs merging with bases of needles. Thoracic neurosetae including three rows of uncini and subuluncini intermixed with capillaries (Fig. 47 B), especially in ventral-most portion of fascicles; uncini including smooth spines (Fig. 46 F) and less numerous smaller, weakly ribbed uncini (Fig. 46 D); subuluncini with minute barbs on capillary extension (Figs. 46 E, 47 B). Abdominal neurosetae including capillaries and 5 – 6 smooth spines (Figs. 46 G, 47 C). Abdominal parapodia dorsally elevated, forming channel with parapodia and setae of right and left sides nearly overlapping medially. Anus terminal, surrounded by lobes, cirri lacking.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06740969FF31FBB2FD20FEFF.taxon	discussion	Remarks. N. dendritica chilensis Hartmann-Schröder is here raised to full species status. This species is similar to N. dendritica, but differs because the neuropodial postsetal lobes are prolonged on their superior most margins instead of being reduced to a small papilla as is typical for N. dendritica. Furthermore, the thoracic neuropodial uncini are mostly smooth instead of being mostly ribbed. The three juvenile specimens from Ecuador (USNM 60637) have more uncini with transverse ridges in the thoracic neuropodia than the adults, but an adult identification was confirmed for the same sample and it is not known how the various setal types develop in orbiniids.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06740969FF31FBB2FD20FEFF.taxon	description	Based on my own observations of N. dendritica from the eastern North Pacific (Blake 1996) and the few specimens of N. chilensis available for study, the differences between the two species are not great and they likely represent a sibling species pair with subtle parapodial and setal differences representing a clinal variation over the distribution from Canada to Chile.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06740969FF31FBB2FD20FEFF.taxon	distribution	Distribution. Ecuador to Chile, intertidal to 10 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0671096BFF31FE7FFC8AF977.taxon	materials_examined	Material examined. Northern Chile, Iqique, LUCE Sta. M- 131, intertidal, red rocks in pools (1, SMNH 154447). — Southern Chile, Seno Reloneavi, Canal Tenglo, between Isla Tengo and Angelmó, LUCE Sta. M- 13, 0 – 6 m (1, SEM, JAB); Seno Reloneavi, Isla Tenglo, the bay on the South Side, LUCE Sta. M- 60, intertidal (4, SMNH 154440); Bahía de Ancud, between Punta San Antonio and Punta Colorado, LUCE Sta. M- 55, intertidal (1, SMNH 154444); Golf Corcovado, Boca del Guafo, Isla Guafo, the anchorage E of Punta Weather, LUCE Sta. M- 70 A, 25 m (1, SMNH 154450); Golfo de Ancud, Canal Caicaen, E of the mouth of Canal Quigua, LUCE Sta. M- 45, 18 m (1, SEM, JAB). — Straits of Magellan, near the estuary of Río los Ciervos, S of Punta Arenas, LUCE Sta. M- 115, intertidal (1, SMNH 154449).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0671096BFF31FE7FFC8AF977.taxon	description	Description. All specimens incomplete; largest fragment nearly complete, 85 mm long and 2.4 mm wide for 146 setigers. Color in alcohol: dark brown. Largest specimens with prostomium truncate, slightly rounded on frontal margin (Figs. 48 A, 49 A, 50 A); eyespots lacking; smaller specimens with prostomium more pear-shaped, blunt on anterior margin (Fig. 48 A); peristomium with two achaetous rings in juveniles and smaller specimens (Fig. 49 A), reduced to a single achaetous ring in larger specimens (Figs. 48 A, 50 A); proboscis not observed. Thoracic region with 19 – 20 setigers (17 according to Gravier 1909), appearing dorsally compressed; abdominal segments cylindrical in cross-section. Thoracic notopodia elongate, cirriform from setiger 1 (Fig. 48 B), continuing through thoracic (Fig. 50 B) and abdominal setigers; neuropodia swollen, bearing large fascicles of setae and a single fingerlike postsetal lobe from setiger 1 (Fig. 48 B); abdominal neuropodia simple, bluntly rounded, bearing a short ventral cirrus (Fig. 48 C); a distinct ventral flange present; interramal cirrus lacking. Thoracic notosetae including 30 – 35 long, crenulated capillaries; abdominal notopodia with 15 or more capillaries and 5 – 6 furcate setae; furcate setae with unequal tynes having blunted, notched tips, tynes connected by row of fine needles appearing as a thin membrane in light microscopy, shaft with ribs along one edge (Figs. 48 H, 49 D), in SEM 6 – 7 needles on either side, merging with tynes; tynes with distinct openings on tips (see arrows, Fig. 50 E). Thoracic neurosetae including 7 – 8 rows of numerous uncini and two rows of crenulated capillaries (Fig. 50 C); uncini with ribbed shaft and a bluntly rounded tip bearing a terminal notch, appearing bifid in some angles; entire end of shaft and tip with distinct lateral flange appearing hood-like in certain views (Figs. 48 D – G, 49 B – C, 50 D), smaller specimens with tips of uncini appearing more notched, probably due to less wear (Fig. 49 B – C); abdominal neurosetae including 1 – 2 thin protruding aciculae with curved blunted tips, sometimes with thin membranous mucron (Fig. 48 I), and 5 – 6 thin crenulated capillaries. Branchiae from setiger 4 on all specimens (Figs. 48 A, 49 A, 50 A); branchiae small, conical at first, increasing in size rapidly over following setigers, becoming cirriform with broad base and tapering to pointed tip; branchiae on abdominal segments considerably larger than on thoracic segments, triangular in shape; branchiae heavily ciliated on both margins. Bases of abdominal branchiae close together, joined by low transverse ridge. Middle thoracic through anterior abdominal segments with pair of oval-shaped dorsal sense organs medial and anterior to branchial bases.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0671096BFF31FE7FFC8AF977.taxon	discussion	Remarks. Naineris grubei is closely related to N. furcillata in the shape of the prostomium, number of thoracic setigers, and distribution and form of the setae. The two species differ in that the notopodia of posterior thoracic and abdominal setigers in N. furcillata have a distinctly forked appearance, whereas in N. grubei the notopodium is simple and entire throughout. Both species have abdominal neuropodia with a short ventral cirrus. The main difference between N. grubei and other congeners is in the nature of the notched or bidentate tips of the thoracic neuropodial uncini. The new collections provide an opportunity to expand the original descriptions of Gravier (1908, 1909). The number of thoracic setigers was reported to be 17 in the original description, while the specimens from the Lund University Chile Expedition always have 19 – 20. The branchiae consistently begin on setiger 4 in the Lund materials, whereas Gravier (1909) indicated that they began on setiger 7 on his specimen from Peru. The small oval dorsal sensory organs of thoracic and anterior abdominal setigers do not appear to have been reported previously. The difference in the number of thoracic setigers and position of the first pair of branchiae between the original account of Gravier (1908, 1909) and the new materials from Chile are likely due to size of the specimens. Graviers’ specimens were smaller, less than 5 mm long and with less than 50 segments. These correspond closely with small specimens considered to be juveniles and identified as N. cf. grubei by Blake (1996) from southern California where the number of thoracic setigers ranged from 8 – 13 and branchiae first occurred from setiger 5 – 6.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0671096BFF31FE7FFC8AF977.taxon	distribution	Distribution. Ecuador, Peru, and Chile, intertidal to 25 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06730965FF31F8E7FD8DF8AA.taxon	materials_examined	Material examined. Argentina, Mar del Plata, Rocas Pya Chica, intertidal, Jan 1973, coll. Marchetti, holotype (USNM 1013686); Feb 1970, coll. J. M. Orensanz, 3 paratypes (USNM 1013687).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06730965FF31F8E7FD8DF8AA.taxon	description	Description. A small species, holotype incomplete, 12 mm long, 0.8 mm wide for 62 setigers; paratypes of similar size, but not well preserved, one complete. Thoracic region with 12 – 13 setigers, with transition to abdomen abrupt, characterized by reduction of neurosetae and change from bidentate to unidentate neuropodial uncini. Prostomium about as wide as long, broadly rounded on anterior margin (Fig. 51 A); no eyespots. Peristomium elongate achaetous region formed of two indistinct rings, more or less fused. Notopodial postsetal lobes elongate, fingerlike throughout body (Fig. 51 A – B). Thoracic neuropodia swollen, forming rounded tori from which setae emerge; postsetal lobes from setiger 1, continuing through abdominal region. Thoracic notosetae crenulated capillaries. Furcate setae absent. Thoracic neurosetae including crenulated capillaries with numerous spinelets along shaft (Fig. 51 C) and bidentate ribbed uncini arranged in 2 – 3 rows; uncini of anterior row shorter, more strongly curved, those of last row longer and straighter (Fig. 51 D – F). Anterior abdominal neurosetae including curved blunt-tipped unidentate uncini and capillaries; posterior abdominal setigers with 2 – 3 unidentate acicular spines, at least one of which has crenulations (Fig. 51 B). Branchiae from setiger 5 – 6 continuing to end of body. Pygidium a rounded lobe with terminal anus; lacking cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06730965FF31F8E7FD8DF8AA.taxon	discussion	Remarks. The specimens studied here are probably juveniles. They are representative of a transitional phase between the traditional definition of a small orbiniid such as Protoariciella, which normally has two achaetous peristomial rings and Naineris, which has one. These specimens are referred to Naineris because juveniles of this genus are known to have two achaetous rings as larvae and juveniles and one as an adult. Naineris argentiniensis n. sp., although represented only by small specimens, has a close relationship with N. grubei, known from the eastern Pacific, in the bifid nature of the neuropodial uncini and occurrence of branchiae from anterior thoracic segments. Naineris argentiniensis n. sp. differs considerably from N. grubei, however, in lacking furcate setae and flail setae, by having a broad, straplike abdominal notopodium instead of one that is thin and fingerlike, having branchiae from setiger 5 – 6 instead of 4, and by having low, rounded abdominal neuropodia instead of elongate, bilobed ones.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06730965FF31F8E7FD8DF8AA.taxon	distribution	Distribution. Argentina, intertidal.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD067F0966FF31F9E7FC5EFC2C.taxon	materials_examined	Material examined. Weddell Sea, Glacier Sta. 69 - 1, 512 m (2, USNM 46604). — Ross Sea, East of Cape Adare, Eltanin Sta. 32 - 1995, 10 Jan 1968, 72.05 ° S, 172.63 ° E, 344 – 348 m, holotype and 3 paratypes (USNM 690405 – 6); N. of Ross Island, Eltanin Sta. 32 - 2050, 22 Jan 1968, 77.03 ° S, 168.50 ° E, 909 – 923 m, 1 paratype (USNM 1013906); Ross Sea, Moubray Bay, off Cape Hallett, Deep Freeze IV, Northwind Sta. 8, 12 Jan 1959, 72.288 ° S, 170.300 ° E, 135 m, 1 paratype (USNM 1013907).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD067F0966FF31F9E7FC5EFC2C.taxon	description	Description. A small species, holotype complete, 7.5 mm long and 0.75 mm wide for 50 setigers. Thoracic region with 9 – 10 setigers; transition from thorax to abdomen generally abrupt, with last 1 – 2 thoracic setigers having fewer neuropodial uncini. Branchiae from setiger 6 – 7 continuing to posterior end of body (Fig. 52 A – B). Anus terminal, located between two rounded lobes, each bearing thin anal cirrus (Fig. 52 B). Prostomium weakly pear-shaped, smoothly rounded on anterior margin (Figs. 52 A, 53 A), no eyespots; paired nuchal organs at margin of prostomium and peristomium (Fig. 53 A, inset). Peristomium with two achaetous rings (Figs. 52 A, 53 A). Notopodia with elongated postsetal lobes throughout body, with those of first few thoracic and last abdominal segments shortest (Figs. 52 A – B, 53 A). Thoracic neuropodia swollen, forming rounded tori from which setae emerge (Fig. 52 C); postsetal lobes first present from setiger 6, continuing to abdominal region. Abdominal neuropodia elongate, rounded apically, with short ventral cirrus (Figs. 52 D, 53 D). Thoracic notosetae including crenulated capillaries and shorter, non-capillary tipped, but sharply pointed setae (Fig. 52 E), and furcate setae. Abdominal notosetae including pointed setae, 1 – 2 heavy, smooth acicular spines (Fig. 52 D, F) and furcate setae; furcate setae with unequal tynes bearing thin needles between tynes (Fig. 52 G); in SEM tynes with entire narrow tips with 4 – 5 needles on either side merging with tynes (Fig. 53 E – F), shafts with few irregular barbs, otherwise smooth. Thoracic neurosetae including crenulated capillaries and ribbed uncini arranged in two rows (Figs. 52 C, H, 53 C); depression or notch visible on concave curvature of spine in light microscopy, with evidence of lateral ribs on some spines, shaft generally appearing smooth (Fig. 52 H); with SEM concave side of curved apex flattened, only weakly notched, shaft with transverse rows of barbs continuing from posterior of curved apex to emergence from neuropodium (Fig. 53 C). Abdominal neurosetae including a few capillaries setae and 1 – 2 strongly curved acicular spines (Figs. 52 I, 53 B, D).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD067F0966FF31F9E7FC5EFC2C.taxon	etymology	Etymology. The species is named for Antarctica, because it is the only species of the genus known from the Southern continent.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD067F0966FF31F9E7FC5EFC2C.taxon	discussion	Remarks. Naineris antarctica n. sp. differs from other species of the genus in having heavy acicular spines in abdominal notopodia which, with the strongly curved neuropodial aciculae provide a striking armature to the abdominal region. The paratypes from Eltanin Sta. 2050 have a somewhat more conical prostomium than the other specimens, but otherwise agree in all other respects.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD067F0966FF31F9E7FC5EFC2C.taxon	distribution	Distribution. Antarctica, Weddell and Ross Seas, 344 – 923 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD067E0966FF31FBABFB3BF8A9.taxon	materials_examined	Type genus. Microrbinia Hartman, 1965, designated by Blake 2000.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD067E0966FF31FBABFB3BF8A9.taxon	diagnosis	Diagnosis. Body small, lacking distinct regions; parapodia lateral throughout, none shifted dorsally. Prostomium broad, bluntly rounded or more elongate and conical; nuchal organs present. Peristomium with 1 – 3 achaetous rings, separated from prostomium. Noto- and neuropodial postsetal lamellae reduced to short lobes. Bases of podia separated throughout; setal tori simple. Setae consisting of capillaries always present, blunt-tipped spines or uncini and swan hooks present or absent; furcate setae typically absent. Branchiae typically absent, rarely present, if present; simple throughout, oval to flattened with two longitudinal rows of cilia. Pygidium with few cirri or cirri absent. Inclusive genera. Microrbinia, Orbiniella, Proscoloplos, and Pettibonella.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD067E0966FF31FBABFB3BF8A9.taxon	discussion	Remarks. Two genera, Orbiniella and Proscoloplos and seven species including two new species were encountered in the present study. The species and genera presently assigned to this subfamily are largely defined on negative characters including the absence of distinct body regions, unmodified posterior parapodia, and often the absence of branchiae. Modified setae are rare and when present are similar to the aciculae found in larger species of the Orbiniinae. Several described species are literally microscopic in size (1 – 3 mm long), approximating dimensions reported for post-larvae of other orbiniids (e. g., Okuda 1946; Blake 1980), suggesting that many species of this subfamily may be juveniles of species in other orbiniid genera. This does not apply to Microrbinia linea Hartman, 1965, a small deep-water species off the U. S. Atlantic coast that Blake (1993) determined was sexually mature year round. Mature ova are also reported for Orbiniella andeepia, O. uniformis, and O. landrumae n. sp. in this paper, and O. nuda, and O. plumisetosa in previous reports (see Table 2; this study, see below). Reports of gametes or other evidence of sexual maturity in other species in this subfamily are rare.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06790961FF31FF73FA49FA13.taxon	description	Synonym: Falklandiella Hartman, 1967. Fide Buzhinskaja 1992: 76. Type species: Falklandiella annulata Hartman, 1967, by monotypy.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06790961FF31FF73FA49FA13.taxon	diagnosis	Diagnosis. Body elongate, with separation between thorax and abdomen indistinct, anterior segments may be narrower than more posterior segments, but size changing gradually over several segments, or no change in appearance between anterior and posterior segments; prostomium broad or elongate with paired nuchal organs usually present, these sometimes pigmented, eyespots present or absent; peristomium with 1 – 2 asetigerous rings. Noto- and neuropodia poorly developed, consisting of low tori from which setae emerge; with only simple postsetal lamellae, or these entirely absent; posterior parapodia not elevated and shifted dorsally as in genera of the Orbiniinae. Capillary noto- and neurosetae always crenulated or weakly camerated with pointed bristles apparent at relatively low magnification (100 x); prominent acicular spines present or absent in noto- and neuropodia, or entirely absent; furcate setae absent. Branchiae entirely absent.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06790961FF31FF73FA49FA13.taxon	discussion	Remarks. Species of Orbiniella are generally small and with a simple morphology, resulting in a taxonomy that is largely based on negative characters. In this respect, it is highly likely that several of the described species are in fact juveniles or post-larval stages of other species of Orbiniidae. This is, however, very difficult to demonstrate without a good growth sequence documenting morphological change. An examination of one of the SEM images of O. marionensis in Gillet (1999: Fig. 2 D) clearly shows that furcate setae are present in the last notopodium on the right side. This suggests that this species at least, is likely a juvenile of another orbiniid. Table 2 provides a list of 13 species of Orbiniella and main morphology. Two other species do not belong in the genus: O. drakei is transferred to Leitoscoloplos (see above) and O. branchiata does not agree with the definition of the genus because it has branchiae, elongate postsetal lamellae, and may be a juvenile of another orbiniid (see below). Of the 13 species listed in Table 2, four occur in deep water and nine occur in shallow water. The four deep-water species all have noto- and neuropodial acicular spines. Of these, O. hobsonae has crenulated acicular spines instead of smooth and O. petersenae is the only one to have four anal cirri. For the two remaining species, O. andeepia has short notopodial postsetal lamellae while O. aciculata has none. Of the nine shallow-water species, both O. landrumae n. sp. and O. marionensis have furcate setae and with further assessment may not belong in Orbiniella at all. In addition, O. landrumae appears to have notopodial flail setae, another character not associated with Orbiniella and its generic assignment is thus provisional. For the remaining seven species, O. dayi has small noto- and neuropodial postsetal lobes that are absent in the other six species. The remaining six species all have noto- and neuropodial acicular spines or short emergent aciculae. Of these, O. spinosa n. sp. has unusual barbed or finely hirsute spines (see below). Apart from eyespots being are reported for O. nuda, O. plumisetosa, and O. annulata, and absent in O. minuta and O. uniformis, these remaining five species are similar in morphology and apart from overall body shape, prostomial shape, and the development of the two peristomial rings are separated with difficulty. The main taxonomic characters for species of Orbiniella are presented in Table 2. Five species, two new are treated below, with “ Orbiniella ” branchiata treated separately.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0679097DFF31F9CDFC0FFE34.taxon	materials_examined	Material examined. Falkland Islands, Eltanin Sta. 8 - 558, 14 Mar 1963, 51.48 ° S, 56.63 ° W, 646 – 845 m, holotype (USNM 55536). — South Pacific Ocean, off Tasmania, Eltanin Sta. 16 - 1418, 86 – 101 m (1, USNM 60629).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0679097DFF31F9CDFC0FFE34.taxon	description	Description. A small species, holotype 3.3 mm long, 0.48 mm wide for 34 setigerous segments; Tasmanian specimen only 1.5 mm long and 0.25 mm wide for 21 setigers. Body not divided into regions; segments simple, with reduced parapodia throughout, tapering somewhat posteriorly. Prostomium sub-triangular not acutely pointed (Fig. 54 A); eyespots not apparent (red eyespots reported from holotype by Hartman (1967) no longer discernable). Peristomium with two achaetous rings. Branchiae absent (Fig. 54 A). Species Body shape Prostomium Peristomial Eyespots Segmental Noto / Neuro Capillary setae Noto / neuro Gametes Pygidium Distribution / depth range; rings annulations post setal acicular References lobes or spines lamellae aciculata Short, thick, Broađly 2 complete, Absent Uni- anđ Absent Crenulateđ 1 % 4 large, Absent With 2 Galapagos Rift, from seđiments Blake, 1985 only 3.2 mm rounđeđ on one or both biannulate conspicuous, short anal near hyđrothermal vents, 2730 long anterior narrow acicular spines cirri m. Blake 1985. margin in both noto- anđ neuropođia andeepia Elongate, Broađly 2 complete, Absent; Uniannulate Present, Crenulateđ Notopođia Eggs Bilobeđ, Antarctica: Drake Passage, Narayanaswamy with up to 68 rounđeđ relatively pigmenteđ notopođia with 1 spine; present in with 2 short Weđđell Sea, South Sanđwich Blake, 2005 setigers anđ anteriorly narrow nuchal only neuropođia largest cirri Slope, 2257 % 5338 m. 120 mm long organs with 2 spines specimens Narayanaswamy & Blake 2005; present This stuđy. annulata Elongate, Triangular, 2 complete Present, Uniannulate Absent Crenulateđ anđ 1 % 2 smooth Absent With 2 Falklanđ Islanđs, 646 % 845 m; Hartman, 1967) thick, with weakly original smooth neuro aciculae rounđeđ off Tasmania, 86 % 101 m. narrow pointeđ đescript; lobes Hartman 1967; This stuđy. segments no longer visible dayi Branch, Elongate, Broađly 2 complete Absent Weakly Present, small Crenulateđ 1 % 2 Absent With 2 Inđian Ocean, Marion Islanđ, 1998 narrow, rounđeđ biannulate throughout neuropođial rounđeđ intertiđal to 15 m. Branch 1998. tapering acicular spines lobes posteriorly; in posterior up to 5 mm segments long hobsonae Elongate, Rounđ on 2, 1 st narrow; absent Uniannulate Absent Crenulateđ 1 % 2 crenulateđ Absent Simple, NE Pacific, Juan đe Fuca Riđge, Blake & Hilbig, threađlike, anterior 2 nđ large; (barbeđ) acicular spines without Enđeavour Seamount, vent site, 1990 4.5 mm long margin both throughout in both noto- lobes or 2216 m. Blake & Hilbig 1990. complete anđ cirri neuropođia landrumae n. Short, thick Broađly 2 not 2 ređ, Uniannulate Short, noto Crenulateđ 1 % 4 elongate Eggs With 4 anal Juan Fernanđez Islanđs,. anteriorly, rounđeđ, complete crescent- postsetal lobes throughout crenulateđ present, cirri, đorsal intertiđal to low water. This tapering smooth on đorsally shapeđ throughout; neuro spines 190 µm pair short, stuđy. posteriorly; anterior eyespots present in with broađ triangular; segments margin present anterior blađes; N. B. ventral pair narrow neuropođia, notopođial long, absent flail anđ cirriform posteriorly furcate notosetae present …… continued on the next page Species Body shape Prostomium Peristomial Eyespots Segmental Noto / Neuro Capillary setae Noto / neuro Gametes Pygidium Distribution / depth range; rings annulations post setal acicular References lobes or spines lamellae marionensis Short, up to Short, 2 complete Absent Biannulate (2) Noto- anđ Crenulateđ 2 % 4 acicular? Rounđeđ Inđian Ocean, Marian Islanđ, Gillet, 1999 7 mm long, broađly neuropođial- spines from with one 95 % 201 m. Gillet 1999. 1.3 mm wiđe rounđeđ postsetal lobes setiger 1 pre-anal present present; N. B. segment notopođial furcate setae present (3) minuta Day, Short, Semi- 2 complete Absent Weakly Absent Crenulateđ Short aciculae? With 2 South Atlantic, Tristan đe narrow, only circular, biannulate barely rounđeđ Cunha, intertiđal. Day 1954. 2 % 3 mm long broađly emerging in lobes rounđeđ miđđle anđ anteriorly posterior segments nuda Hobson, Elongate, Broađly 2 incomplete 2 Uniannulate Absent “ spinous ” 2 % 4 Sperm Bilobeđ NE Pacific, Washington, narrow, 5 % 11 rounđeđ subđermal capillaries neuropođial present; intertiđal. Hobson 1974. mm long anteriorly aciculae eggs not observeđ petersenae Elongate, Broađly 2 complete absent Bi anđ Present Crenulateđ 1 % 3 smooth Present, With 4 NE Atlantic, 133 % 197 m anđ Parapar et al. narrow, rounđeđ triannulate (4) notopođia noto- anđ oocytes short lobes 1490 % 1915 m. Parapar 2015 (6); anteriorly only, small neuroaciculae ca. 60 unpublisheđ đata by the late µm (5) Mary E. Petersen. plumisetosa Elongate, Broađly 2 complete 2 black Uniannulate Absent short smooth 2 % 4 curveđ Eggs With 2 Commanđer Islanđs, Bering Sea, Buzhinskaja, weakly rounđeđ on subđermal caps + neuroaciculae present rounđeđ intertiđal. Buzhinskaja 1993. fusiform, anterior eyespots Crenulateđ caps 225 µm; lobes narrow margin with long sperm posteriorly plumose fibrils packets present spinosa n. sp. Elongate, Elongate, 2, not Absent Uniannulate Absent Crenulateđ 1 % 2 curveđ Absent With 2 Off Argentina on đrifting kelp. narrow, with rounđeđ complete throughout neuro spines blunt lobes This stuđy. short anteriorly đorsally with barbeđ or segments hirsute tips uniformis Long, linear, Short, 2, not Absent Uniannulate Absent Crenulateđ, 2 % 3 emergent Eggs With 2 Antarctic Peninsula, shallow Hartman, 1967 most broađly complete most thicker pointeđ neuro present, large water; Hartman 1967; This segments as rounđeđ on đorsally with curve on aciculae 150 µm ventral stuđy. long as wiđe anterior shaft lobes; 2 margin short đorsal cirri Not incluđing O. branchiata, likely a juvenile of another orbiniiđ; not incluđing O. drakei, herein transferređ to Leitoscoloplos; (2) Baseđ on SEMs (Gillet 1999: Figs. 2 B % C); (3) Notopođial furcate setae are clearly present in last notopođium on the right siđe of the SEM figuređ by Gillet (1999: Fig. 2 D); (4) Line đrawings in Parapar et al. (2015: Fig. 3) show only uniannulate segments along the bođy; (5) Measurements of oocytes taken from unpublisheđ đata on this species by the late Mary E. Petersen, who left đetaileđ illustrations anđ notes. (6) Two đistinct đepth ranges suggest that two species are present rather one. Parapodia represented by low mounds from which setae project; dorsal and ventral cirri absent. Notosetae including crenulated and smooth capillaries from very thin to heavy (Fig. 54 C); neurosetae including crenulated capillaries with thickened shafts, tapering abruptly to long thin tips, and 1 – 2 smooth aciculae, first present from about setiger 12 (Fig. 54 B). Pygidium with terminal anus between two rounded lobes; without anal cirri (Fig. 54 A).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0679097DFF31F9CDFC0FFE34.taxon	discussion	Remarks. Hartman (1967) considered that Falklandiella annulata was related to orbiniids, but stopped short of referring the genus to the family. After examining the holotype from the Falkland Islands and the new specimen from off Tasmania, it is clear that the species should definitely be referred to the Orbiniidae. The crenulated capillaries and the heavier serrated setae are distinctive for orbiniids. There is no apparent separation of the body into a thorax and abdomen, and this is what caused Hartman (1967) the most difficulty in interpretation. The lack of distinct body regions is however, characteristic of species of Microrbiniinae and this species should be referred to the genus Orbiniella, first suggested by Buzhinskaja (1992) and confirmed here. Among the nine shallow-water species listed in Table 2, Orbiniella annulata is most similar to O. nuda and O. plumisetosa in having eyespots and to the latter species in having complete peristomial rings instead of dorsally incomplete. Orbiniella annulata was described with red spots, whereas O. plumisetosa was reported to black subdermal eyespots. However, upon re-examination the eyespots were not visible in the holotype of O. annulata, having faded after 50 years in preservative.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0679097DFF31F9CDFC0FFE34.taxon	distribution	Distribution. Falkland Islands, 646 – 845 m; off Tasmania, 86 – 101 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097DFF31FDACFC04FA23.taxon	materials_examined	Material examined. Off Argentina, 38 ° 46 ′ S, 55 ° 20 ′ W, on drifting Macrocystis holdfasts, coll. J. M. Orensanz (holotype, USNM 1013688).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097DFF31FDACFC04FA23.taxon	description	Description. A small species, holotype 2.1 mm long, 0.2 mm wide, for 22 setigerous segments. Body not divided into distinct regions; posterior parapodia not dorsally elevated; body cylindrical throughout, individual setigerous segments narrower than long, similar throughout, posterior most segments more flattened dorsoventrally. Setal changes mainly with neurosetae anterior to posterior. Branchiae entirely absent. Pygidium with two blunt lobes, without anal cirri (Fig. 54 D). Color in alcohol light tan. Prostomium elongate, rounded on anterior margin (Fig. 54 D), eyespots absent; nuchal organs extending from posterior margin of prostomium, under first peristomial annulation. Peristomium about 1.3 x as long as prostomium with two achaetous rings, each of same size, with lateral annulae not cutting across dorsum (Fig. 54 D). Parapodia reduced to low mounds from which setae emerge; no postsetal lamellae. Setae consisting of crenulated capillaries and curved spines; furcate setae absent; no evidence of imbedded aciculae. Notosetae 2 – 3 crenulated capillaries throughout, with longest and narrowest capillaries in anterior half of body (Fig. 54 E); neurosetae shorter, generally thicker than notosetae numbering 2 – 3 in anterior setigers and 1 – 2 in far posterior setigers; anterior neurosetae spine-like capillaries (Fig. 54 F); posterior setigers with longer, thicker curved spines (Fig. 54 G); initially 1 – 2 curved spines with smooth shaft and narrow curved tip with short barbs on convex side; some far posterior spines with fine hirsute covering on apical end and curved tip (Fig. 54 G).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097DFF31FDACFC04FA23.taxon	etymology	Etymology. The name spinosa is from the Latin, spina for thorn, and refers to the distinctive neuropodial spines that characterize the species.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097DFF31FDACFC04FA23.taxon	discussion	Remarks. The holotype of Orbiniella spinosa n. sp. was originally identified as Falklandiella annulata, but a more careful study suggested that a separate species with more setal complexity was evident. The morphology of the thick, sharply curved neuropodial spines differs from other species of the genus (See Table 2).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097DFF31FDACFC04FA23.taxon	distribution	Distribution. Off Argentina, found on drifting kelp (Macrocystis sp.).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097FFF31F9DDFD1BFEDC.taxon	materials_examined	Material examined. Antarctic Peninsula, Anvers Island, Arthur Harbor, USCG Staten Island Sta. 6 - 63, 24 Jan 1963, 64.77 ° S, 64.07 ° W, ~ 7 m, fish trap, holotype, and 2 paratypes (USNM 47329 – 30).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097FFF31F9DDFD1BFEDC.taxon	description	Description. Body long, linear, holotype 6 mm long, 0.4 mm wide for 30 setigerous segments. Body generally uniform in overall appearance, with a weakly defined thoracic region only vaguely separated from an abdominal region at setiger 6. Prostomium short, broadly rounded on anterior margin (Fig. 55 A); peristomium 3 x as long as prostomium, with two smoothly rounded rings, second forming ventral oral lips. Noto- and neuropodia of setigers 1 – 5 with few long, thin, tapering crenulated capillaries (Fig. 55 D); capillaries from setiger 6 and subsequent segments shorter, thicker, with distinct curve or bend in shaft (Figs. 55 E – F); crenulations of thoracic setae extending along most of exposed setal shaft; in abdominal segments crenulations occuring only from bend of shaft. Abdominal neuropodia with 2 – 3 emergent, pointed aciculae (Figs. 55 G – H). Setigers 16 – 19 swollen, with several large eggs about 150 µm in longest dimension (Fig. 55 B). Pygidium with two large ventral lobes bearing two short, dorsal cirriform appendages (Fig. 55 C).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097FFF31F9DDFD1BFEDC.taxon	discussion	Remarks. Orbiniella uniformis was well described by Hartman (1967). Illustrations are presented here for the first time. The long threadlike nature of this species readily distinguishes it from other orbiniids encountered in this study. Orbiniella uniformis is most closely related to four other shallow-water species (Table 2). Eyespots are reported for O. nuda, O. plumisetesa, O. annulata, and absent in O. minuta and O. uniformis. Further, while the pygidium all of these species consists of two rounded lobes, O. uniformis is the only one with two short dorsal cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0665097FFF31F9DDFD1BFEDC.taxon	distribution	Distribution. Antarctic Peninsula, low water.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0667097FFF31FE84FC9FF9C6.taxon	materials_examined	Material examined. Juan Fernandez Islands, Anton Bruun Cruise 12, Sta. 65 - 240, 12 Dec 1965, 33.622 ° S, 78.839 ° W, 26 – 29 m, holotype and 3 paratypes (USNM 1013912 – 3); Sta. 65 - 243, 12 Dec 1965, 33.62 ° S, 78.847 ° W, 0 – 10 m, 3 paratypes (USNM 1013914).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0667097FFF31FE84FC9FF9C6.taxon	description	Description. A small species, holotype complete, 2.23 mm long, 0.29 mm wide for 23 setigers; one incomplete paratype 2.86 mm long, 0.2 mm wide for 20 setigers; other paratypes smaller. Color in alcohol: opaque white. Prostomium smoothly rounded on anterior margin; with two crescent-shaped red eyespots (Fig. 56 A). Peristomium with two indistinct achaetous rings, but distinctly separated from setiger 1. All segments similar, with no demarcation between thorax and abdomen. Notopodia with short digitiform postsetal lobes throughout; neuropodia with short postsetal lobes in anterior setigers; absent in posterior setigers. Notosetae including 3 – 4 crenulated capillaries (Fig. 56 B), a single flail seta (Fig. 56 C) and a single furcate seta (Fig. 56 D); flail seta with tapering tip and reduced numbers of crenulations; furcate seta with unequal tynes, shorter blunt-tipped, longer thinner and pointed; tynes connected by thin webbing with fine needles. Neurosetae including crenulated capillaries and 1 – 2 modified crenulated spines in anterior setigers and 0 – 1 crenulated capillaries and 3 – 4 spines in posterior setigers; spines unique, recurved, with broad crenulated blade terminating in pointed tip (Fig. 56 E). Branchiae absent. Some specimens with large yolky eggs up to 190 µm across widest dimension. Eggs with two nucleoli observed in germinal vesicle (Fig. 56 F). Pygidium with anus directed posteriorly, surrounded by four cirri; dorsal pair shorter, triangular in shape, ventral pair longer and cirriform (Fig. 56 G).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0667097FFF31FE84FC9FF9C6.taxon	etymology	Etymology. This species is named for Ms. Betty J. Landrum of the former Smithsonian Oceanographic Sorting Center. Ms. Landrum provided support and encouragement during the course of this study and of another project on Antarctic polychaetes.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0667097FFF31FE84FC9FF9C6.taxon	discussion	Remarks. Orbiniella landrumae n. sp. is only provisionally referred to Orbiniella because it differs from related species in having notopodial furcate setae, flail setae, and an unusual type of crenulated neuropodial spine. However, the species does not have distinct body regions, parapodia are reduced, branchiae are absent, two peristomial rings are present, and the posterior parapodia are not elevated as is typical for species of Orbiniella. Further, large ova of 190 µm present in the holotype indicate sexual maturity. Further study is needed to more adequately address the generic placement of this species.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0667097FFF31FE84FC9FF9C6.taxon	distribution	Distribution. Juan Fernandez Islands, intertidal to 29 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06670978FF31F9B1FBDFFEDC.taxon	materials_examined	Material examined. — Drake Passage, ANDEEP I ANT XIX- 3, R / V Polarstern, Sta. PS- 61 / 114 - 7, 2900 m (1, JAB). — Weddell Sea, ANDEEP II ANT XIX- 4, R / V Polarstern, Sta. PS- 61 / 139 - 10, 3965 m (1, ZMH P- 27801); PS- 61 / 141 - 7, 2260 m (1, ZMH P- 27802); ANDEEP III ANT XXII- 3, R / V Polarstern, Sta. PS- 67 / 110 - 4, 4700 m (1, SEM, JAB); Sta. PS- 67 / 110 - 5, 4702 m (1, ZMH P- 27803); Sta. PS- 67 / 121 - 10, 2663 m (1, ZMH P- 27804); Weddell Sea, abyssal plain, ANDEEP SYSTCO ANT XXIV- 2, R / V Polarstern, Sta. 33 - 14, 5338 m (1, ZMH P- 27805).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06670978FF31F9B1FBDFFEDC.taxon	description	Description. A large specimen from ANDEEP III Station PS- 67, 11 – 12 mm long, 0.6 mm wide for 68 normal setigerous segments and four setigers as part of a narrow regenerating posterior pygidial end. Morphology of prostomium and peristomium same as originally reported for smaller specimens. Prostomium broadly rounded anteriorly (Fig. 57 A), exhibiting methyl green staining reaction; peristomium with two achaetous rings (Fig. 57 A). Eyespots absent; two pigmented nuchal organs present. First 12 setigers narrower than following ones suggesting a weak differentiation of body into thoracic and abdominal regions. Each setigerous segment with prominent encircling glandular ridge or ring encompassing dorsum, venter, and parapodia; this ring occupying most of surface of narrower anterior segments, then restricted to posterior one-third of longer abdominal segments; glandular ring with a weak methyl green staining reaction. Each notopodium with a short post-setal lamella (Fig. 57 C), smaller than originally reported, but proportional in size on larger specimens; neuropodial lamellae absent. Setae including crenulated capillaries in both noto- and neuropodia (Fig 57 B); 1 – 2 spines occurring in notopodia and neuropodia; spines smooth and pointed (Fig. 57 C). Branchiae absent. Narrow posterior end appears to be regenerating; anal cirri absent.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06670978FF31F9B1FBDFFEDC.taxon	discussion	Remarks. The larger specimens found at Sta. PS 67 110 - 4 confirm the generic placement of Orbiniella andeepia. If the original specimens had been juveniles of a larger orbiniid then adult characters of other genera would have been present in the large specimen. There is no evidence of elevated abdominal parapodia as characterizes most other orbiniids. Furcate setae and branchiae are entirely absent. The methyl green staining reaction of the prostomium and the encircling segmental ring is newly reported. Of the four deep-water species of Orbiniella in Table 2, all have noto- and neuropodial acicular spines. Of these, O. andeepia and O. petersenae have notopodial lamellae while O. hobsonae and O. aciculata do not. Orbiniella hobsonae has crenulated acicular spines instead of smooth spines as in the other three species. Orbiniella aciculata and O. petersenae have two and four anal cirri, respectively; O. andeepia and O. hobsonae have none. Orbiniella andeepia is the only deep-water species of Orbiniella in the Southern Ocean.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06670978FF31F9B1FBDFFEDC.taxon	distribution	Distribution. Southern Ocean in slope and abyssal depths, 2257 – 5338 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06600978FF31FE84FD43FC01.taxon	materials_examined	Material examined. Drake Passage, Eltanin Sta. 9 - 740, 18 Sep 1963, 56.10 ° S, 66.32 ° W, 384 – 494 m, holotype (USNM 55533).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06600978FF31FE84FD43FC01.taxon	description	Description. Holotype incomplete, small, 4 mm long, 0.8 mm wide for 22 setigerous segments. Prostomium much wider than long, tapering anteriorly, rounded on anterior margin, Eyespots absent. Peristomium with three narrow asetigerous rings; separation of thorax and abdomen gradual, indistinct, occurring from setiger 14; branchiae from setiger 4, long at first, broad basally, tapering apically, continuing to posterior segments; noto- and neuropodial postsetal lobes simple, fingerlike; subpodial lobes or fringe lacking; notosetae including crenulated capillaries and furcate setae; neurosetae including thoracic and abdominal capillaries and abdominal aciculae.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06600978FF31FE84FD43FC01.taxon	discussion	Remarks. The holotype was well described by Hartman (1967). As a species of Orbiniella, O. branchiata is unusual in the presence of three achaetous peristomial rings, which should serve to readily differentiate the species from other orbiniids. However, given the small size of the holotype, the presence of branchiae, elongate postsetal lobes, and furcate setae, the species most likely represents a juvenile of another species in another genus.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06600978FF31FE84FD43FC01.taxon	distribution	Distribution. Drake Passage, 384 – 494 m.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06600978FF31FBFEFA57F8DA.taxon	diagnosis	Diagnosis. Body short, with separation between thorax and abdomen indistinct and with body segments of similar shape and size throughout, with no change in appearance between anterior and posterior segments. Prostomium broadly rounded or elongate, with paired rounded nuchal organs present; eyespots present or absent. Peristomium with two asetigerous rings. Noto- and neuropodia poorly developed, consisting of low tori from which setae emerge; with simple, tapering post-setal lamellae; posterior parapodia not shifted dorsally. Setae including crenulated capillary noto- and neurosetae and distinct swan hooks present from anterior neuropodia; furcate setae entirely absent. Branchiae present from anterior parapodia continuing posteriorly. Pygidium with four cirri.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD06600978FF31FBFEFA57F8DA.taxon	discussion	Remarks. Pettibonella Solís-Weiss & Fauchald, 1989 and Proscoloplos are the only two orbiniid genera having swan hooks. Pettibonella was differentiated from Proscoloplos by Solís-Weiss & Fauchald (1989) in that their type-species, P. multiuncinata has eyes instead of lacking them, has elongate instead of short branchiae, has thoracic neuropodial uncini and capillaries, and has swan hooks of two kinds instead of one in posterior setigers. Within the Orbiniidae the presence or absence of eyespots is widespread among the genera including the closely related genus Orbiniella, where eyespots are typically found in shallow-water species and absent in deep-water species (see above). Differential shape and length of branchiae is a useful species-level character among orbiniids genera but is not used to define any other genus in the family. Proscoloplos cygnochaetus is now believed to be the only species of that genus and there are swan hooks of larger and smaller sizes within a single neuropodium (see below). The presence of thoracic neuropodial uncini is therefore the most obvious character that differentiates Pettibonella from Proscoloplos and is similar to the manner in which Leitoscoloplos is separated from Scoloplos.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0660097AFF31F885FD74FA5D.taxon	materials_examined	Material examined. Juan Fernandez Islands, Anton Bruun Cruise 12, Sta. 65 - 240, 24 – 27 m, (1, USNM 60646). — Juan Fernandez Islands, Chile Bay, behind Punta Suroeste, Anton Bruun Cruise 12, Sta. 134, shallow subtidal (1, USNM 65240). — Argentina, Golfo San Matías, IBM Sta. SAO V- 201 (1, USNM 1407115); Sta. SAO V- 236 (1, USNM 1407116).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0660097AFF31F885FD74FA5D.taxon	description	Description. A small species, present specimens 3.5 mm long and 0.35 mm wide for up to 40 setigerous segments. Color in alcohol: opaque white. Body cylindrical throughout, slightly expanded in anterior setigers. Prostomium short, smoothly rounded on anterior margin; no eyespots; peristomium with two achaetous rings (Fig. 58 A – B). Anterior parapodia all similar; thoracic and abdominal region demarcated by reduction of neuropodial lobes and appearance of neuropodial swan hooks on setiger 7 – 9. Branchiae from setigers 5 – 6 (Fig. 58 A – B). Body narrowing posteriorly; pygidium with two dorsal and two ventral cirri (Fig. 58 C). Notopodia of anterior and posterior setigers simple, with cirriform postsetal lobes (Fig. 58 D). Notosetae all crenulated capillaries; neurosetae of first 6 – 8 setigers all capillaries; two neuropodial swan hooks present from setiger 7 – 9 (Fig. 58 E); superior hook accompanied by 2 – 3 delicate capillaries; superior hook distinctly larger than inferior hook and with more prominent apical teeth; hooks with large main fang surmounted by 3 – 5 apical teeth (Fig. 58 E – F); shaft of both hooks bent, with swelling at point of bend. Branchiae from setiger 5 – 6, continuing to near posterior end of body; each branchia short, stubby, with several internal bacillary glands (Fig. 58 B).	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0660097AFF31F885FD74FA5D.taxon	discussion	Remarks. The form of the neuropodial swan hooks readily differentiate this species from all other orbiniids from the area of study. These setae resemble long handled uncini found in other families, not known from any other orbiniid. Three species of Proscoloplos have been described: P. cygnochaetus from Tristan de Cunha and South Africa by Day (1954, 1967), P. confusus from Chile by Hartmann-Schröder (1962 b), and P. bondi from near Sydney, Australia by Kelaher & Rouse (2003). All three species are similar morphologically with the main characters used to separate them being minor differences in the form of the swan hooks and the segmental occurrence of branchiae and hooks. Kelaher & Rouse (2003) examined hundreds of specimens of their P. bondi as part of year-long collections and did not find any evidence of gametes. These authors did, however, find evidence of asexual reproduction and regeneration. Meyer et al. (2008) identified specimens of Proscoloplos from the French Atlantic coast and initiated a study to compare morphology using SEM and molecular markers ITS 1 and ITS 2 of specimens from France, South Africa, and Australia; SEM was used for a paratype of P. confusus from Chile. No characters were identified to support three species and the molecular results did not result in any clades separating the three widespread populations that would support the retention of three distinct species. Meyer et al. (2008) therefore suggested that both P. confusus and P. bondi were synonyms of P. cygnochaetus. These authors also found no evidence of gametes in any materials examined but did find regenerating specimens in the French populations. Habitats recorded for the species in Australia and France included turf algae. Hartmann-Schroder (1962 b) also reported P. confusus from intertidal algae. In order to account for the widespread distribution of P. cygnochaetus Meyer et al. (2008) suggested that algal growth on the hulls of ships could provide a comparable habitat to support short or long-distance transport. The specimens examined here exhibited branchiae from setigers 5 – 6 and swan hooks from setigers 7 – 9 which is within the range of variability reported by Kelaher & Rouse (2003) and Meyer et al. (2008). I conclude therefore, that Chilean specimens described as P. confusus are in fact synonymous with P. cygnochaetus.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
8F2387DD0660097AFF31F885FD74FA5D.taxon	distribution	Distribution. Chilean coast, intertidal with algae; off the Chilean coast and Juan Fernandez Islands, shallow subtidal, 27 m; Argentina, subtidal. Also from NSW Australia, South Africa, and the French coast in intertidal to shallow subtidal habitats associated with algae.	en	Blake, James A. (2017): Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America. Zootaxa 4218 (1): 1-145, DOI: 10.5281/zenodo.245827
