taxonID	type	description	language	source
A5678797FFE7FFD0FF68FB59D7E0A5BE.taxon	materials_examined	Type species: Amblyosyllis rhombeata Grube & Ørsted in Grube, 1858	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE7FFD0FF68FB59D7E0A5BE.taxon	diagnosis	Diagnosis. Relatively small-sized body, with few chaetigers and marked intersegmental constrictions; dorsal pigmentation patterns present in some species. Palps free from each other, usually short, ventrally bent beneath prostomium. Prostomium ovate with 3 antennae and 2 pairs of eyes, eyes frequently coalescent on each side of prostomium; anterior eyespots present in some species; nuchal organs as a pair of dorsal projections on posterior part of prostomium, rounded, ovate or digitiform, running posteriorwards for variable extension (epaulettes). Peristomium dorsally short, with 2 pairs of cirri. Antennae, peristomial, dorsal cirri throughout and anal cirri elongate, wrinkled to pseudoarticulated, with conspicuous cirrophores, sometimes with well-defined articles distally; ventral cirri frequently longer than parapodial lobes; antennae and cirri usually with iridescent granules. Compound chaetae as falcigers only, blades bidentate, with short spinulation. Dorsal and ventral simple chaetae rarely present. Aciculae straight, distally pointed, tips frequently protruding from parapodial lobes. Last segment achaetous; pygidium with one pair of long cirri. Pharynx coiled or sinuated, trepan with denticles with variable number of cuspids, central tooth absent; proventricle usually relatively short.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE7FFD0FF68FB59D7E0A5BE.taxon	discussion	Remarks. Members of Amblyosyllis have the palps ventrally bent, nuchal organs as epaulettes, and convoluted pharynx, features that characterize the subfamily Autolytinae Langerhans, 1879, however, the genus has recently been placed among the ' Incertae Sedis' (Aguado et al. 2012). We included Amblyosyllis in the present paper because it has been traditionally allocated within the Eusyllinae, due to the conspicuous ventral cirri and the morphology of falcigers and aciculae, which clearly differ from those of Autolytinae. Also, the reproductive mode likely involves the epigamy (San Martín & Hutchings 2006), typical of the Eusyllinae, which is confirmed by our finding of one specimen undergoing epigamous maturation process (Fig. 1 A). The authorship of this genus has been inaccurately attributed to " Grube, 1857 ", probably due to confusions with publication dates and different reprints repaginations of the original description. This was recently corrected by Salazar-Vallejo & Eibye-Jacobsen (2012).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE4FFD6FF68FEDAD434A182.taxon	materials_examined	Material examined. Project ' BioPol'. Ubatuba — Praia do Félix (23 ° 23 ' 34 " S 44 ° 58 ' 19 " W): 1 spec. (MZUSP 2384), 4 Nov 2002. São Sebastião — Praia de São Francisco (23 ° 44 ' 54 " S 45 ° 24 ' 33 " W): 1 spec., 19 Apr 2003; Praia do Araçá (23 ° 48 ' 54 " S 45 ° 24 ' 24 " W): 2 specs, 25 Sep 2003. Additional material examined. Amblyosyllis granosa. Atlantic Ocean, Strait of Magellan, Punta Arenas: 1 spec. (type, ZMH V- 4751), coll. H. Mag. Samm., 73, det. Ehlers, 1897.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE4FFD6FF68FEDAD434A182.taxon	description	Description. Small-sized body, largest specimen examined ~ 5 mm long, 0.8 mm wide, with 13 chaetigers. Palps ovate, completely free from each other. Prostomium ovate with 2 coalescent pairs of eyes in trapezoidal arrangement (Fig. 1 A – B); lateral antennae inserted on anterior margin of prostomium, with up to 15 articles each; median antenna inserted slightly posterior to lateral ones, ~ 1 / 3 longer, with up to 21 subequal articles, basally smooth, with large cirrophore (Fig. 1 A – B); nuchal epaulettes relatively short, extending until close to posterior border of chaetiger 1 (Fig. 1 B). Peristomium dorsally short; dorsal peristomial cirri longer than median antenna, with up to 38 articles each, ventral peristomial cirri slightly shorter than lateral antennae, with ~ 10 articles each (Fig. 1 A). Dorsal cirri throughout of nearly even length, with 20 – 30 articles each, distal articles tapering; ventral cirri ovate, prominent, extending beyond parapodial lobes (Fig. 1 A). Antennae and cirri throughout with yellow to reddish granular inclusions (Fig. 1 A). Parapodial lobes distally bilobed. Anterior parapodia with 16 – 23 falcigers each; posterior parapodia with 25 – 35 falcigers each. Falciger shafts slightly spinulated subdistally, shafts progressivelly stouter towards posterior body (Fig. 2 A – B); falciger blades spinulated, with short straight spines, and bidentate, distal tooth larger; blades with dorso-ventral gradation in length, 42 – 22 Μm long on anterior body, 36 – 22 Μm long on posterior body (Fig. 2 A – B). Dorsal and ventral simple chaetae not observed. Anterior parapodia with up to 5 aciculae each (Fig. 2 C), progressively less aciculae per parapodium towards posterior body, last ones with only 2 aciculae each (Fig. 2 D); aciculae differing from each other only in thickness, all straight, distally pointed, tips protruding from parapodial lobes (Fig. 2 C – D). Pygidium rounded, anal cirri similar to dorsal cirri, incomplete in all specimens examined. Pharynx long, slender, with sinuation anterior to proventricle (Fig. 1 C); trepan with 6 tricuspidate teeth inserted in lobate base (Figs 1 C, 2 E); proventricle extending for ~ 1.5 segments, with ~ 13 muscle cell rows (Fig. 1 A, C).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE4FFD6FF68FEDAD434A182.taxon	biology_ecology	Biology. One specimen showed intracoelomic oocytes in chaetigers 6 – 11 and long natatory chaetae, indicating that it was starting to reproduce by epigamy (Fig. 1 A).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE4FFD6FF68FEDAD434A182.taxon	discussion	Remarks. The only species of Amblyosyllis reported from Brazilian waters (Nogueira 2000) is A. formosa (Claparède, 1863), which has longer falciger blades (80 – 40 Μm) than A. granosa (42 – 22 Μm) and a trepan with monocuspidate teeth (tricuspidate in A. granosa). However, we examined these Brazilian specimens identified as A. formosa and they actually belong to a different species, probably still undescribed. We do not include that species in the present paper because the state of preservation of the material available does not allow for a proper description of the species.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE4FFD6FF68FEDAD434A182.taxon	materials_examined	Type locality. Strait of Magellan (Atlantic Ocean).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE4FFD6FF68FEDAD434A182.taxon	distribution	Distribution. Pacific Ocean: Galápagos Islands. Atlantic Ocean: Strait of Magellan. First occurrence for the Brazilian coast.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE2FFD6FF68FAC1D749A24B.taxon	materials_examined	Type species: Pionosyllis weismanni Langerhans, 1879, designated by San Martín et al. 2009.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE2FFD6FF68FAC1D749A24B.taxon	diagnosis	Diagnosis. Relatively small to mid-sized body, sometimes slender, elongate. Palps only basally fused, triangular, distally tapering. Prostomium usually with 2 pairs of eyes, 1 pair of anterior eyespots and 3 antennae. Peristomium with 2 pairs of cirri. Antennae, peristomial cirri and dorsal cirri of chaetiger 1 elongate, dorsal cirri of remaining chaetigers distinctly shorter, frequently nearly ovate; ventral cirri throughout digitiform, of similar size to parapodial lobes. Compound chaetae as falcigers only, blades bidentate, with short spinulation. Dorsal and ventral simple chaetae present at least on posteriormost chaetigers; ventral simple chaetae thick, bidentate, usually with translucent hood covering subdistal tooth. Pharynx with single tooth, close to anterior margin; proventricle similar in length to pharynx. Reproduction by epigamy (San Martín et al. 2009).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE2FFD6FF68FAC1D749A24B.taxon	discussion	Remarks. The genus currently includes five known species (San Martín et al. 2009), our finding representing the first account for Brazilian waters.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE2FFDBFF68F888D0F4A6CE.taxon	materials_examined	Material examined. Project ' REVIZEE'. State of Rio de Janeiro — 21 º 51´S 40 º 07´W, 110 m: 4 specs (MZUSP 2486), 2 Mar 1998; 22 º 02 ’ S 40 º 05 ’ W, 93 m: 3 specs (MZUSP 2485), 2 Mar 1998; 22 º 50´S 40 º 51´W, 105 m: 2 specs (ZUEC-POL 16203), 1 Mar 1998; 23 º 08´S 41 º 00´W, 105 m: 5 specs (ZUEC-POL 16202), 1 Mar 1998; 23 º 26´S 41 º 15´W, 145 m: 11 specs (MZUSP 2484), 28 Feb 1998; 23 º 36´S 42 º 09´W, 187 m: 9 specs (ZUEC-POL 16201), 16 Feb 1998; 23 º 40´S 42 º 31´W, 162 m: 18 specs (MZUSP 2483), 16 Feb 1998; 23 º 49´S 43 º 14´W, 138 m: 1 spec. (ZUEC-POL 16200), 15 Feb 1998; 24 º 02´S 43 º 30´W, 147 m: 5 specs (MZUSP 2482), 14 Feb 1998. State of São Paulo — 24 º 07 ’ S 44 º 42´W, 101 m: 1 spec. (ZUEC-POL 16199), 11 Jan 1998; 24 º 07 ’ S 45 º 51 ’ W, 147 m: 4 specs (MZUSP 2478), 9 Jan 1998; 24 º 17 ’ S 44 º 12 ’ W, 163 m: 1 spec. (MZUSP 2479), 10 Jan 1998; 24 º 20 ' S 44 º 09 ' W, 258 m: 2 specs (ZUEC-POL 16198), 10 Jan 1998; 24 º 49´S 44 º 44´W, 153 m: 2 specs (MZUSP 2481), 12 Jan 1998; 25 º 36 ’ S 45 º 13 ’ W, 380 m: 1 spec., 13 Jan 1998; 26 º 27 ’ S 44 º 30 ’ W, 165 m: 1 spec. (MZUSP 2480), 11 Jan 1998. Project ' Habitats'. 21 ° 9 ' 9 " S 40 ° 16 ' 5 " W, 101 m: 1 spec. (MZUSP 2459), 7 Mar 2009, and 14 specs (MZUSP 2477; ZUEC-POL 16197), 21 Jul 2009; 21 ° 22 ' 58 " S 40 ° 19 ' 41 " W, 52 m: 1 spec. (ZUEC-POL 16184), 5 Mar 2009; 21 ° 42 ' 53 " S 40 ° 10 ' 15 " W, 98 m: 2 specs (MZUSP 2461; ZUEC-POL 16185), 9 Mar 2009, and 4 specs (MZUSP 2475; ZUEC-POL 16195), 7 Jul 2009; 21 ° 43 ' 10 " S 40 ° 11 ' 30 " W, 73 m: 1 spec. (MZUSP 2460), 9 Mar 2009; 21 ° 45 ' 14 " S 40 ° 14 ' 7 " W, 67 m: 3 specs, 14 Mar 2009; 21 ° 45 ' 15 " S 40 ° 14 ' 8 " W, 66 m: 1 spec. (ZUEC-POL 16174), 14 Mar 2009, and 2 specs, 8 Jul 2009; 22 ° 3 ' 38 " S 40 ° 6 ' 59 " W, 90 m: 16 specs (MZUSP 2473; ZUEC-POL 16193), 6 Jul 2009; 22 ° 3 ' 45 " S 40 ° 9 ' 59 " W, 75 m: 2 specs (MZUSP 2456), 25 Feb 2009, and 2 specs (MZUSP 2472), 6 Jul 2009; 22 ° 4 ' 14 " S 40 ° 6 ' 59 " W, 92 m: 7 specs (MZUSP 2457; ZUEC-POL 16182), 25 Feb 2009; 22 ° 6 ' 10 " S 40 ° 3 ' 6 " W, 154 m: 28 specs (MZUSP 2458; ZUEC-POL 16183), 24 Feb 2009, and 23 specs (MZUSP 2474), 7 Jul 2009; 22 ° 12 ' 38 " S 40 ° 13 ' 19 " W, 99 m: 1 spec. (MZUSP 2470), 5 Jul 2009; 22 ° 17 ' 25 " S 40 ° 6 ' 35 " W, 143 m: 9 specs (MZUSP 2455; ZUEC-POL 16181), 24 Feb 2009, and 2 specs (MZUSP 2471; ZUEC-POL 16192), 5 Jul 2009; 22 ° 19 ' 31 " S 40 ° 37 ' 19 " W, 73 m: 1 spec. (MZUSP 2467), 4 Jul 2009; 22 ° 23 ' 38 " S 40 ° 20 ' 40 " W, 153 m: 9 specs (MZUSP 2454; ZUEC-POL 16180), 23 Feb 2009, and 5 specs (MZUSP 2469; ZUEC-POL 16191), 4 Jul 2009; 22 ° 23 ' 20 " S 40 ° 34 ' 56 " W, 110 m: 3 specs (MZUSP 2476; ZUEC-POL 16196), 25 Jul 2009; 22 ° 31 ' 7 " S 40 ° 31 ' 32 " W, 139 m: 12 specs (MZUSP 2453; ZUEC-POL 16179), 23 Feb 2009, and 10 specs (MZUSP 2468; ZUEC-POL 16190), 3 Jul 2009; 22 ° 52 ' 1 " S 40 ° 57 ' 29 " W, 92 m: 2 specs (MZUSP 2451), 22 Feb 2009 and 2 specs (MZUSP 2465), 3 Jul 2009; 22 ° 57 ' 28 " S 40 ° 50 ' 30 " W, 143 m: 9 specs (MZUSP 2452; ZUEC-POL 16178), 21 Feb 2009 and 7 specs (MZUSP 2466; ZUEC-POL 16189), 3 Jul 2009; 23 ° 10 ' 4 " S 41 ° 3 ' 6 " W, 107 m: 7 specs (MZUSP 2449; ZUEC- POL 16176), 21 Feb 2009 and 9 specs (MZUSP 2463; ZUEC-POL 16187), 2 Jul 2009; 23 ° 11 ' 28 " S 41 ° 0 ' 47 " W, 150 m: 31 specs (MZUSP 2450; ZUEC-POL 16177), 21 Feb 2009; 23 ° 12 ' 8 " S 40 ° 59 ' 35 " W, 142 m: 29 specs (MZUSP 2464; ZUEC-POL 16188), 2 Jul 2009; 23 ° 36 ' 14 " S 41 ° 21 ' 29 " W, 142 m: 2 specs (MZUSP 2448; ZUEC-POL 16175), 1 Mar 2009 and 9 specs (MZUSP 2462; ZUEC-POL 16186), 1 Jul 2009. Additional material examined. Brevicirrosyllis ancori (San Martín & Hutchings, 2006) — Australia, Queensland, Great Barrier Reef, Outer Younge Reef (14 ° 36 ' S 145 ° 38 ' E), rock covered with coralline algae and encrusting sponges, 9 m: 1 spec. (holotype, AM W 29244), coll. P. Hutchings, 21 Jan 1977, det. G. San Martín, 15 Nov 2004; same locality, rock with Lithothamnion and Halimeda, 30 m: 4 specs (AM W 28962), coll. P. Hutchings, 24 Jan 1977, det. G. San Martín, 2003. Brevicirrosyllis mariae — Australia, Queensland, Great Barrier Reef, Outer Younge Reef (14 ° 36 ' S 145 ° 38 ' E), rock with Lithothamnion and Halimeda, 30 m: 1 spec. (holotype, AM W 28454), coll. P. Hutchings, 24 Jan 1977, det. G. San Martín, 2003; same locality, on rock covered with coralline algae, 9 m: 1 spec. (paratype, AM W 28921), coll. P. Hutchings, 21 Jan 1977, det. G. San Martín, 2003.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE2FFDBFF68F888D0F4A6CE.taxon	description	Description. Long, slender body, largest specimen examined ~ 8.5 mm long, 0.3 mm wide, with 82 chaetigers; body without pigmentation pattern, dorsally with discontinuous rows of cilia on anterior margin of some chaetigers, and between dorsal cirri and corresponding parapodial lobes (Fig. 4 B, D). Prostomium ovate, shorter than palps, with 2 pairs of eyes in open trapezoidal arrangement and 1 pair of anterior eyespots (Fig. 3 A); antennae wrinkled to irregularly articulated, lateral antennae inserted slightly anteriorly to anterior eyes, median antenna inserted on posterior part of prostomium, between posterior eyes, approximately twice as long as lateral antennae (Figs 3 A; 4 A). Peristomium dorsally short, about half length of anterior chaetigers; dorsal peristomial cirri slightly longer than lateral antennae, ventral peristomial cirri about half length of dorsal ones (Figs 3 A; 4 A, C); nuchal organs as transverse row of cilia on anterior margin of peristomium (Fig. 4 B). Dorsal cirri of chaetiger 1 elongate, slightly shorter than median antenna, wrinkled to irregularly articulated; dorsal cirri on chaetiger 2 absent; dorsal cirri of remaining chaetigers short, ovate to club-shaped, slightly longer than parapodial lobes, with fibrilar inclusions on distal half (Figs 3 A – B; 4 A, C, E; 5 A – C). Ventral cirri digitiform, thin, about half width of dorsal cirri, approximately as long as parapodial lobes (Fig. 5 A – B). Parapodial lobes conical, with conspicuous parapodial glands with dorsal pores in some specimens (Fig. 4 D), more evident on posterior body. Parapodia throughout with 3 – 5 falcigers each; falcigers with dorso-ventral gradation in length of shafts, ventralmost chaetae about half length of dorsalmost; blades bidentate, teeth close to each other, subdistal smaller than distal one on dorsalmost chaetae, progressively larger ventralwards, teeth about same size on ventralmost midbody falcigers; dorsalmost falcigers with relatively thin blades, with short spinulation, ventralmost falcigers with curved blades, with slightly larger spinulation (Fig. 3 D – E; 5 D – E); blades of dorsalmost falcigers on anterior body up to 34 µm long, intermediate ~ 20 µm long, ventralmost falcigers ~ 12 µm long (Figs 3 D; 5 D – E); falcigers on mid- and posterior body with blades as long as dorsalmost and ventralmost ones of anterior body, blades of intermediate sizes absent (Fig. 3 E). Dorsal simple chaetae present from proventricle chaetigers, irregularly truncate distally, slightly spinulated subdistally (Fig. 3 F); ventral simple chaetae only present on posterior body, approximately as thick as falciger shafts, bidentate, subdistal tooth hooked, with tendon connecting tip of subdistal tooth to lateral of chaetae (Figs 3 C; 5 F). Anterior body parapodia with 2 aciculae each, one straight, with acute tip, other distally bent at almost right angle (Fig. 3 G); posterior body parapodia with only 1 acicula each, bent at almost right angle. Pygidium distally rounded, with pair of long, thin anal cirri (Fig. 5 B). Pharynx extending for 4 – 5 chaetigers (Fig. 3 A), triangular tooth at opening, border surrounded by soft, rounded papillae (Fig. 5 A); proventricle approximately as long as pharynx, with ~ 30 – 35 muscle cell rows. (Fig. 3 A).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE2FFDBFF68F888D0F4A6CE.taxon	discussion	Remarks. Brevicirrosyllis mariae resembles B. weismanni in body shape and chaetae morphology throughout, as well as in the presence of fibrilar inclusions in the dorsal cirri. However, B. mariae is shorter, up to ~ 8 mm long, against ~ 18 mm long in B. weismanni (San Martín & Hutchings 2006), and lacks dorsal cirri on chaetiger 2 (present on all chaetigers in B. weismanni). One of the specimens here examined showed a dorsal cirrus on one side of chaetiger 2 (Fig. 4 A, C), without noticeable scar on the opposite side parapodium. Since all other body measurements were similar to those of B. mariae, we tentatively considered the specimen as belonging to this species.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE2FFDBFF68F888D0F4A6CE.taxon	materials_examined	Type locality. Australia — Queensland, Great Barrier Reef, Outer Yonge Reef (Pacific Ocean).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE2FFDBFF68F888D0F4A6CE.taxon	distribution	Distribution. Pacific Ocean: Australia (Queensland, New South Wales). First record for the Atlantic Ocean.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFEFFFDBFF68FC10D0EDA3CA.taxon	materials_examined	Type species: Eusyllis blomstrandi Malmgren, 1867	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFEFFFDBFF68FC10D0EDA3CA.taxon	diagnosis	Diagnosis. Medium to small sized eusyllines. Prostomium with 2 pairs of eyes, additional 1 pair of anterior eyespots occasionally present, and 3 antennae. Peristomium with 2 pairs of peristomial cirri. Antennae, peristomial and dorsal cirri throughout usually smooth, sometimes wrinkled to pseudoarticulated. Ventral cirri usually ovate to digitiform, ventral cirri of chaetiger 1 laminated, flattened, in some species. Compound chaetae throughout as heterogomph falcigers only, sometimes with elongated blades; dorsal and ventral simple chaetae only present on posterior body parapodia. Pharynx straight, armed with conical dorsomedial tooth and usually incomplete trepan, with denticles in ventral half only; trepan complete in larger specimens of some species.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFEFFFDBFF68FC10D0EDA3CA.taxon	discussion	Remarks. Members of this genus often have fragile bodies, breaking apart at intersegmental grooves, and antennae and cirri easily falling off. So, preserved material usually consists of numerous fragments of each specimen. Two of the species treated in the present paper, Eusyllis liniata comb. nov. and E. nonatoi sp. nov., present inverted dorso-ventral gradation in the length of falciger blades (i. e., blades of dorsalmost falcigers are shorter than those of ventralmost ones) comparing to most syllids, although such condition in not always mentioned in species descriptions. However, a similar pattern has been observed for many species of Odontosyllis Claparède, 1863 (see Fukuda et al. 2013), which suggests that this should be better investigated in other taxa. The genus currently consists of 10 species, including both new species described herein (cf. Brusa et al. 2013).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFEFFFD9FF68F909D429A5BE.taxon	materials_examined	Material examined. Project ' REVIZEE '. State of São Paulo — 24 º 07´S 44 º 42´W, 101 m: 6 specs (ZUEC-POL 10459), 11 Jan 1998; 24 º 07 ’ S 45 º 51 ’ W, 147 m: 34 specs (MZUSP 1384), 9 Jan 1998; 24 º 20´S 44 º 09´W, 258 m: 2 specs (MZUSP 1383), 10 Jan 1998; 25 º 36 ’ S 45 º 13 ’ W, 380 m: 1 spec., 13 Jan 1998. Project ' Habitats '. 21 ° 22 ' 58 " S 40 ° 19 ' 41 " W, 52 m: 3 specs (MZUSP 1392; ZUEC-POL 12927), 5 Mar 2009, and 2 specs (MZUSP 1393), 21 Jul 2009; 21 ° 42 ' 53 " S 40 ° 10 ' 15 " W, 98 m: 4 specs (MZUSP 1391; ZUEC-POL 12725), 9 Mar 2009; 21 ° 43 ' 9 " S 40 ° 11 ' 30 " W, 73 m: 5 specs (MZUSP 1390; ZUEC-POL 11040), 9 Mar 2009; 22 ° 3 ' 38 " S 40 ° 6 ' 59 " W, 89 m: 1 spec. (MZUSP 1389), 6 Jul 2009; 22 ° 3 ' 45 " S 40 ° 9 ' 59 " W, 75 m: 1 spec. (ZUEC-POL 10555), 25 Feb 2009; 22 ° 4 ' 14 " S 40 ° 6 ' 59 " W, 91 m: 1 spec. (MZUSP 1388), 25 Feb 2009; 22 ° 31 ' 7 " S 40 ° 31 ' 32 " W, 139 m: 1 spec. (MZUSP 1387), 23 Feb 2009; 22 ° 46 ' 54 " S 41 ° 3 ' 32 " W, 77 m: 1 spec. (ZUEC-POL 10552), 22 Feb 2009, and 2 specs (MZUSP 1386), 2 Jul 2009; 22 ° 52 ' 1 " S 40 ° 57 ' 28 " W, 92 m: 1 spec. (ZUEC-POL 10464), 22 Feb 2009; 22 ° 57 ' 28 " S 40 ° 50 ' 30 " W, 142 m: 1 spec., 21 Feb 2009; 23 ° 10 ' 4 " S 41 ° 3 ' 6 " W, 105 m: 2 specs (MZUSP 1385), 21 Feb 2009. Additional material examined. Eusyllis assimilis — Spain, Castellón, Columbretes Islands, N of Columbrete Grande, 45 m: 8 specs (MNCN 16.01 / 8640), coll. Campanha Fauna III, 12 Jul 1994, det. G. San Martín; W of Columbrete Grande, 65 – 67.8 m: 1 spec. (MNCN 16.01 / 8645), coll. Campanha Fauna IV, 18 Jul 1996, det. G. San Martín. Australia, Western Australia, Kalbarri, Red Bluff, rocky shore (27 ° 42 ' S 114 ° 09 ' E), 3 m: 5 specs (AM W 28941), coll. J. K. Lowry, 10 Jan 1984, det. G. San Martín. Tasmanian Sea, Taupo Seamont (33 ° 16 ' 51 " S 156 ° 09 ' 09 " E), 244 m: 17 specs (AM W 28925), coll. J. K. Lowry and party, R / V ' Franklin', 0 2 May 1989, det. G. San Martín.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFEFFFD9FF68F909D429A5BE.taxon	description	Description. Relatively small-sized body, largest specimens examined 3.15 mm long, 0.56 mm wide, with 35 segments. Palps ovate, divergent, basally fused. Prostomium ovate with 2 pairs of eyes in trapezoidal arrangement and 1 pair of anterior eyespots (Fig. 6 A); lateral antennae inserted on anterior margin of prostomium; median antenna inserted more posteriorly, on middle of prostomium, about twice as long as lateral antennae; nuchal organs as one pair of broad semi-circular rows of cilia close to posterior border of prostomium (Fig. 7 A, C). Peristomium shorter than subsequent segments; dorsal peristomial cirri about same length as median antenna, ventral peristomial cirri approximately same size as lateral antennae. Dorsal cirri of chaetiger 1 longer than remaining dorsal cirri, up to twice as long as dorsal peristomial cirri; remaining dorsal cirri alternating long cirri, as long as dorsal peristomial cirri, and short cirri, as long as ventral peristomial cirri, dorsal cirri progressivelly shorter towards posterior body. Antennae, peristomial, some anterior body dorsal cirri and anal cirri irregularly articulated distally (Figs 6 A; 7 A). Ventral cirri shorter than parapodial lobes, ovate on anterior body (Fig. 7 B), progressively pyriform towards posterior body. Parapodial lobes conical. Anterior parapodia with up to 30 falcigers each, midbody with 9 – 15, posterior parapodia with ~ 5 falcigers each; shafts of falcigers subdistally spinulated, with straight tips (Figs 6 B – C; 7 E – J); parapodia with 1 – 4 dorsalmost falcigers with thinner shafts, blades longer and thinner than remaining falcigers; blades of these longer falcigers bidentate, teeth of even size throughout, and up to ~ 42 Μm long on anterior body, ~ 25 Μm long on mid- and posterior body (Figs 6 B; 7 E, H); remaining falcigers with blades with short spinulation; blades bidentate, teeth of even size on anterior body (Figs 6 B; 7 F), subdistal tooth progressively larger and slightly hooked towards posterior body (Figs 6 C; 7 G, I – J); blades 25 – 15 Μm long on anterior body and midbody, 17 – 12 Μm long on posterior body. Dorsal simple chaetae only present on posterior body, thinner than shafts of falcigers, subdistally spinulated, unidentate (Fig. 6 D); ventral simple chaetae only present on posterior body, slightly spinulated subdistally, bidentate, subdistal tooth larger than distal one (Fig. 6 E). Anterior parapodia with 2 aciculae each, one of them subdistally bent, with rounded tip, another straight, distally pointed (Fig. 6 F); midbody and posterior parapodia with only 1 acicula each, thicker than those of anterior body chaetigers and more pronouncedly curved, with rounded tip (Fig. 6 G). Pygidium with pair of elongate anal cirri, up to same length as dorsal peristomial cirri. Pharynx through ~ 6 segments, opening surrounded by 10 large papillae; large, conical central tooth close to opening and complete or incomplete trepan formed by 25 – 45 denticles, more evident on ventral half (Figs 6 A; 7 A – B, D); proventricle through ~ 8 – 9 segments, with 45 – 50 muscle cell rows (Fig. 6 A).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFEFFFD9FF68F909D429A5BE.taxon	discussion	Remarks. The number of denticles in the trepan may vary and, usually, is difficult to assess, as these structures are tiny and only visible in dissected specimens, or in those with fully everted pharynx. Brusa et al. (2013) report that some specimens from the Mediterranean Sea and the Pacific Ocean may present a complete trepan, as observed in some of our specimens (Fig. 7 D).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFEFFFD9FF68F909D429A5BE.taxon	materials_examined	Type locality. Italy — around Triest (Adriatic Sea).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFEFFFD9FF68F909D429A5BE.taxon	distribution	Distribution. Pacific Ocean: New Zealand; Australia; Japan. Indian Ocean: Australia. Mediterranean Sea. Atlantic Ocean: East Atlantic Ocean, from English Channel to South Africa; Northwest Atlantic Ocean, from Canada to México (San Martín 2003; San Martín & Hutchings 2006; Brusa et al. 2013). First occurrence in South American coasts.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE8FFDCFF68FF6AD651A3DC.taxon	materials_examined	Material examined. Peru, Callao, between La Punta and El Camotal Island, on rhizoids of Macrocystis: 4 specs (paratypes, ZMH P- 19652), coll. Nodt, 29 May 1956; 3 specs (ZMH P- 14758), coll. Nodt, 29 May 1956.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE8FFDCFF68FF6AD651A3DC.taxon	description	Description. Relatively small-sized body, largest fragment analysed with 22 segments, ~ 3 mm long, 0.35 mm wide. Faint pigmentation present on some specimens, as a discontinuous transverse dark stripe dorsally, at midlength of some anterior segments, more conspicuous close to bases of dorsal cirri, another longitudinal line dorso-laterally, close to each body lateral, and scattered dark spots on some cirri. Palps irregularly rounded, basally fused, ventrally bent to some extent. Prostomium ovate with 2 pairs of eyes in trapezoidal arrangement; antennae smooth to weakly wrinkled, lateral antennae inserted on anterior margin of prostomium, extending to almost twice length of palps; median antenna inserted more posteriorly, ~ 1 / 4 longer than lateral antennae. Peristomium shorter than subsequent segments; dorsal peristomial cirri up to same size as median antenna, ventral peristomial cirri approximately same size as lateral antennae. Dorsal cirri of chaetiger 1 usually longer than dorsal peristomial cirri; remaining dorsal cirri alternating longer cirri, as long as dorsal peristomial cirri, and shorter cirri, as long as ventral peristomial cirri. Antennae, peristomial and dorsal cirri with short cirrophores; cirrostyles distally pointing, lanceolate (Fig. 8 A). Ventral cirri slightly longer than parapodial lobes on first chaetigers, as long as parapodial lobes on following ones, ovate. Parapodial lobes conical to slightly bilobed, posterior lobe longer. Anterior parapodia with ~ 20 falcigers each, midbody with 12 – 20; shafts of falcigers subdistally spinulated, with straight tips; connective between shafts and blades spinulated, more conspicuously in dorsalmost chaetae; blades of falcigers spinulated and unidentate to subbidentate (Fig. 8 B – C); blades with inverted dorso-ventral gradation in length, ~ 10 – 15 Μm long. Dorsal simple chaetae present from right after proventricle chaetigers, thinner than shafts of falcigers, subdistally spinulated, bayonet-like shaped (Fig. 8 D); ventral simple chaetae not observed. Anterior parapodia with up to 2 aciculae each, one of them distally irregularly blunt, other slightly enlarged distally, with one side more pronounced than other (Fig. 8 E); midbody parapodia with 1 acicula each, thicker than on anterior body, subdistally bent, with rounded tip (Fig. 8 F). Pharynx through 3 – 4 segments with large, conical central tooth close to opening and trepan with 12 teeth (Fig. 8 G); proventricle through ~ 5 segments, with ~ 50 muscle cell rows (Fig. 8 A).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE8FFDCFF68FF6AD651A3DC.taxon	discussion	Remarks. Eusyllis liniata comb. nov. was recently redescribed by Verdes et al. (2011) as Odontosyllis liniata but, for some features, such as the pharynx armature, the redescription was based in the original description (Hartmann-Schröder 1962). However, the trepan in Odontosyllis has teeth pointing backwards and lacks central pharyngeal tooth, which differs from the structure we have observed in the paratypes of E. liniata comb. nov., as well as from the trepan illustrated in the original description (Hartmann-Schröder 1962, pl. 9, fig. 56). Furthermore, other characters of E. liniata comb. nov. more closely resemble Eusyllis than Odontosyllis. Compared to the Brazilian species of Eusyllis, E. liniata comb. nov. presents falcigers resembling those of E. nonatoi sp. nov., except in the coarser spinulation on blades (Figs 8 B – C and 9 B – C), and thick, distally bent aciculae, similar to those of E. assimilis (see Figs 6 G and 8 F). In addition, the bayonet-like dorsal simple chaetae of E. liniata comb. nov. resemble those of Eusyllis kupfferi Langerhans, 1879 (see San Martín & Hutchings 2006). The holotype (ZMH P- 14757) is possibly missing, since the vial was found empty.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE8FFDCFF68FF6AD651A3DC.taxon	materials_examined	Type locality. Peru — Callao (Pacific Ocean). Distributon. Only known from Peru (Pacific Ocean).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE8FFC0FF68F903D1BCA1AE.taxon	materials_examined	Material examined. Project ' BIOTA '. Ubatuba — Praia da Fazenda (23 ° 21 ' 25 " S 44 ° 51 ' 55 " W), on rocky shore: 1 spec., 16 Oct 2001; Praia de Picinguaba (23 ° 22 ' 31 " S 44 ° 50 ' 21 " W), on rocky shore: 1 spec. (ZUEC-POL 16210), 9 May 2001; 2 specs (ZUEC-POL 16213), 17 Oct 2001; on Sargassum: 27 specs (ZUEC-POL 16211 – 16212), 8 Jun 2001; 68 specs (holotype, MUSP 2346; paratype 1, ZUEC-POL 16090; paratype 2, MZUSP 2347; 13 paratypes, MZUSP 2348; remaining specs, MZUSP 2494), 18 Oct 2001. Caraguatatuba — Praia Martim de Sá (23 ° 37 ' 34 " S 45 ° 22 ' 31 " W), on Sargassum: 11 specs (ZUEC-POL 16209), 16 Mar 2001; 52 specs (paratype 3, ZUEC-POL 16091; paratype 4, MZUSP 2354; 2 paratypes, USNM 1273435; remaining specs, MZUSP 2493), 27 Sep 2001. São Sebastião — Praia da Baleia (23 ° 46 ' 48 " S 45 ° 39 ' 51 " W), on rocky shore: 1 spec. (ZUEC-POL 16208), 8 Apr 2001; on Sargassum: 2 specs (paratypes, MNCN 16.01 / 13188), 10 Apr 2001; 31 specs (MZUSP 2492), 14 Nov 2001. Project ' BIOPOL'. Ubatuba — Praia do Félix (23 ° 23 ' 34 " S 44 ° 58 ' 19 " W): 1 spec. (ZUEC-POL 16205), 4 Nov 2002; Praia de Domingas Dias (23 ° 30 ' 00 " S 45 ° 08 ' 38 " W): 1 spec. (MZUSP 2489), 2 Nov 2002. São Sebastião — Praia da Baleia (23 ° 46 ' 48 " S 45 ° 39 ' 51 " W): 12 specs (MZUSP 2487), 23 Jul 2005; 2 specs (ZUEC-POL 16204), 17 Oct 2005; Praia de Toque-Toque Grande (23 ° 50 ' 12 " S 45 ° 30 ' 40 " W): 13 specs (MZUSP 2490), 21 Jul 2005. Guarujá — Praia de Pernambuco (23 ° 58 ' 20 " S 46 ° 11 ' 02 " W): 7 specs (MZUSP 2491), 22 Jun 2005; 8 specs (ZUEC- POL 16207), 4 Oct 2005. Itanhaém — Praia do Sonho (24 ° 11 ' 44 " S 46 ° 48 ' 05 " W): 2 specs (MZUSP 2488), 14 Jun 2003; 1 spec. (ZUEC-POL 16206), 26 Aug 2003. Type series. All type specimens collected by the Project ' BIOTA ' team. Holotype (MZUSP 2346), paratypes 1 – 2 (ZUEC-POL 16090 and MZUSP 2347, respectively) and thirteen paratypes (MZUSP 2348) collected at Praia de Pincinguaba (23 ° 22 ' 31 " S 44 ° 50 ' 21 " W), Ubatuba, State of São Paulo, Brazil, intertidal, on assemblage of algae, 18 Oct 2001. Paratypes 3 – 4 (ZUEC-POL 16091 and MZUSP 2354, respectively) and two other paratypes (USNM 1273435) collected at Praia Martim de Sá (23 ° 37 ' 34 " S 45 ° 22 ' 31 " W), Caraguatatuba, State of São Paulo, Brazil, intertidal, on Sargassum, 27 Sep 2001. Two paratypes (MNCN 16.01 / 13188) collected at Praia da Baleia (23 ° 46 ' 48 " S 45 ° 39 ' 51 " W), São Sebastião, State of São Paulo, Brazil, intertidal, on Sargassum, 10 Apr 2001. Morphological data of selected specimens of the type series are provided in Table 1.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE8FFC0FF68F903D1BCA1AE.taxon	description	Description. Relatively small bodied, largest specimen examined paratype 2 (MZUSP 2347), 5.56 mm long, 0.33 mm wide, with 41 segments (Table 1). Pigmentation as 2 transverse, dark stripes dorsally per segment, one at each margin, anterior and posterior, usually more evident on midbody chaetigers (Figs 9 A; 10 A). Palps distally rounded, fused along basal 1 / 3, occasionaly only with tip to distal half bent ventralwards (Figs 9 A; 10 B, D). Prostomium ovate, nearly rounded, with 2 pairs of eyes in open trapezoidal arrangement and 1 pair of small, anterior eyesposts (Figs 9 A; 10 A); lateral antennae inserted slightly anteriorly to anterior pair of eyes, extending slightly beyond palps; median antenna inserted centrally, between eyes or slightly backwards, up to 2.5 times longer than lateral antennae (Figs 9 A; 10 A – B); nuchal organ as a transverse, discontinuous row of cilia around posterior margin of prostomium (Fig. 10 B). Peristomium dorsally short; dorsal peristomial cirri approximately as long as median antenna or slightly longer, ventral peristomial cirri ~ 1 / 4 length of dorsal ones (Figs 9 A; 10 B). Dorsal cirri of chaetiger 1 longer than dorsal peristomial cirri; dorsal cirri of chaetigers 2 – 6 irregularly alternating in length, between those of dorsal and ventral peristomial cirri; from chaetiger 7 onwards, dorsal cirri alternating in length, longer cirri slightly longer than ventral peristomial cirri, usually directed upwards, shorter cirri approximately same length as ventral peristomial cirri or slightly shorter, usually directed laterally (Figs 9 A; 10 A – B, E). Lateral antennae, ventral peristomial cirri and shorter dorsal cirri spindle-shaped; antennae and cirri throughout smooth to wrinkled, antennae and longer cirri on anterior body frequently distally articulated; cirrophores present (Figs 9 A; 10 A – B, D – E). Ventral cirri ovate, as long as or slightly longer than parapodial lobes (Fig. 10 D). Parapodial lobes dorsally with 2 tufts of cilia, one close to bases of cirrophores, another near tips of lobes (Fig. 10 E). Anterior parapodia with 9 – 10 falcigers each, midbody with 7 – 13, posterior parapodia with 3 – 7 falcigers each (Table 1); shafts of falcigers distally spinulated (Figs 9 B – C; 10 C, H – I); blades unidentate, some chaetae on anterior body chaetigers with finely spinulated blades, remaining falcigers with smooth blades; blades with dorso-ventral gradation in length and shape, dorsalmost blades shorter and more strongly falcate, specially on mid- and posterior body, blades ~ 7 – 15 µm long (Figs 9 B – C; 10 C, H – I; Table 1). Dorsal simple chaetae usually present from anterior body, almost straight, slightly bent distally, spinulated, distally rounded (Fig. 9 D) to bifid, with nearly inconspicuous teeth (Fig. 10 I); ventral simple chaetae only present on posteriormost parapodia, bidentate to subbidentate, subdistal tooth smaller than distal one (Fig. 9 E; Table 1). Anterior parapodia with 2 aciculae each, one of which straight, distally tapering, another distally irregularly expanded and spinulated (Fig. 9 F); mid- and posterior parapodia with 1 acicula each, of the second type (Fig. 9 G). Pharynx though 3 – 3.5 segments, opening surrounded by 10 large, rounded papillae, internally with fringe of cilia (Figs 9 A; 10 D, F – G; Table 1); central tooth relatively small, slightly conical, in anterior third of pharynx; trepan incomplete, with ~ 16 small teeth more conspicuous on ventral half, dorsal half frequently just subtly serrated (Fig. 10 F); proventricle wider than pharynx, relatively short, through 2.5 – 3 segments, with ~ 25 – 30 muscle cell rows (Fig. 9 A; Table 1).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE8FFC0FF68F903D1BCA1AE.taxon	discussion	Remarks. Eusyllis nonatoi sp. nov. has falcigers with unidentate blades, as in E. kupfferi and E. maxima (Monro, 1930). However, E. kupfferi has blades longer than E. nonatoi sp. nov. (up to 27 µm long) and the characteristic bayonet-shaped dorsal simple chaetae (San Martín & Hutchings 2006). Eusyllis maxima is a conspicuously larger species, with 80 – 100 falcigers in each anterior parapodium, dorsalmost falcigers with bidentate blades, and proventricle through 4 – 10 segments, with ~ 120 muscle cell rows (Jiménez et al. 1995).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFE8FFC0FF68F903D1BCA1AE.taxon	etymology	Etymology. The species is named in honor of Prof. Edmundo Ferraz Nonato, the scientific father, grandfather and great-grandfather of all polychaetologists in Brazil, who recently passed away at the age 93.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF4FFC0FF68FAE5D6F9A2E7.taxon	materials_examined	Type species: Opisthodonta morena Langerhans, 1879	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF4FFC0FF68FAE5D6F9A2E7.taxon	diagnosis	Diagnosis. Body of medium to large size. Prostomium with 2 pairs of eyes and 1 pair of anterior eyespots; 3 antennae; palps basally fused, usually broader than prostomium. Nuchal organs as 1 pair of ciliated grooves between prostomium and peristomium; peristomium with 2 pairs of cirri. Antennae, peristomial and dorsal cirri throughout smooth, long and slender; anterior ventral cirri foliaceous, fused to parapodial lobes on anteriormost chaetigers, remaining ventral cirri conical to digitiform. Compound chaetae as falcigers with bidentate blades, usually heavily spinulated; spiniger-like chaetae present in some species. Dorsal and ventral simple chaetae rarely present. Massive pharynx and proventricle, pharyngeal tooth away from anterior margin, usually near mid-length of pharynx; trepan absent. Reproduction by epigamy (cf. San Martín 2003).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF4FFC0FF68FAE5D6F9A2E7.taxon	discussion	Remarks. Despite being relatively large syllids, members of Opisthodonta have fragile bodies, easily breaking apart by handling. Depending on the collection methodology, complete specimens are rarely obtained, thus accurate descriptions of these taxa are frequently not possible. In some cases, such as in Opisthodonta russelli San Martín, López & Aguado, 2009, original descriptions were based only on fragments; thus, some data on posterior body characters are first reported herein. This is the first occurrence of the genus for the Brazilian coast.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF5FFC5FF68FF6AD1A9A40E.taxon	materials_examined	Material examined. Project‘ REVIZEE ’. State of Rio de Janeiro — 23 º 08´S 41 º 00´W, 105 m: 1 spec. (MZUSP 1010), 1 Mar 1998; 23 º 26´S 41 º 15´W, 145 m: 1 spec., 28 Feb 1998; 23 º 29´S 41 º 09´W, 266 m: 1 spec. (MZUSP 1009), 28 Feb 1998; 23 º 36´S 42 º 09´W, 187 m: 3 specs, 16 Feb 1998; 23 º 40´S 42 º 31´W, 162 m: 1 spec. (MZUSP 1008), 16 Feb 1998; 23 º 49´S 43 º 14´W, 138 m: 5 specs, 15 Feb 1998; 24 º 02´S 43 º 30´W, 147 m: 3 specs, 14 Feb 1998. State of São Paulo — 24 º 07´S 44 º 42´W, 101 m: 3 specs, 11 Jan 1998; 24 º 07´S 45 º 51´W, 147 m: 18 specs (MZUSP 1006), 9 Jan 1998; 24 º 20´S 44 º 09´W, 258 m: 1 spec., 10 Jan 1998; 25 º 18´S 44 º 52´W, 808 m: 1 spec., 12 Jan 1998; 26 º 27´S 44 º 30´W, 165 m: 1 spec. (MZUSP 1007), 11 Jan 1998. Project ' Habitats '. 21 ° 9 ' 9 " S 40 ° 16 ' 5 " W, 101 m: 2 specs (MZUSP 2396), 7 Mar 2009, and 2 specs (MZUSP 2405), 21 Jul 2009; 21 ° 22 ' 58 " S 40 ° 19 ' 41 " W, 52 m: 1 spec. (ZUEC-POL 16127), 5 Mar 2009, and 1 spec. (ZUEC- POL 16136), 21 Jul 2009; 21 ° 23 ' 38 " S 40 ° 15 ' 37 " W, 88 m: 1 spec. (ZUEC-POL 16137), 21 Jul 2009; 21 ° 24 ' 43 " S 40 ° 25 ' 18 " W, 33 m: 1 spec. (MZUSP 2386), 7 Mar 2009; 21 ° 42 ' 53 " S 40 ° 10 ' 16 " W, 98 m: 2 specs (MZUSP 2398; ZUEC-POL 16144), 9 Mar 2009; 21 ° 43 ' 10 " S 40 ° 11 ' 30 " W, 71 m: 1 spec. (MZUSP 2404), 7 Jul 2009; 21 ° 45 ' 13 " S 40 ° 14 ' 7 " W, 67 m: 1 spec. (MZUSP 2387), 14 Mar 2009; 22 ° 3 ' 38 " S 40 ° 6 ' 59 " W, 90 m: 3 specs (MZUSP 2403; ZUEC-POL 16145), 7 Jul 2009; 22 ° 3 ' 45 " S 40 ° 9 ' 59 " W, 75 m: 4 specs (MZUSP 2394; ZUEC-POL 16125), 25 Feb 2009, and 4 specs (MZUSP 2402; ZUEC-POL 16133), 6 Jul 2009; 22 ° 6 ' 12 " S 40 ° 3 ' 5 " W, 150 m: 1 spec. (ZUEC- POL 16134), 7 Jul 2009; 22 ° 13 ' 42 " S 40 ° 32 ' 39 " W, 70 m: 1 spec. (ZUEC-POL 16117), 24 Jul 2009; 22 ° 17 ' 42 " S 40 ° 26 ' 59 " W, 104 m: 1 spec. (MZUSP 2395), 23 Feb 2009, and 9 specs (MZUSP 2401; ZUEC-POL 16131, 16143), 4 Jul 2009; 22 ° 19 ' 3 " S 40 ° 5 ' 28 " W, 386 m: 1 spec. (MZUSP 2385), 30 Jan 2009; 22 ° 19 ' 32 " S 40 ° 37 ' 18 " W, 75 m: 12 specs (MZUSP 2393; ZUEC-POL 16126), 15 Mar 2009, and 8 specs (MZUSP 2400; ZUEC-POL 16129), 4 Jul 2009; 22 ° 23 ' 21 " S 40 ° 34 ' 57 " W, 110 m: 1 spec. (ZUEC-POL 16135), 25 Jul 2009; 22 ° 23 ' 39 " S 40 ° 20 ' 40 " W, 153 m: 1 spec. (ZUEC-POL 16124), 23 Feb 2009, and 2 specs (ZUEC-POL 16132), 4 Jul 2009; 22 ° 31 ' 7 " S 40 ° 31 ' 32 " W, 139 m: 1 spec. (ZUEC-POL 16123), 23 Feb 2009, and 2 specs (ZUEC-POL 16130), 3 Jul 2009; 22 ° 46 ' 54 " S 41 ° 3 ' 33 " W, 77 m: 3 specs (MZUSP 2392; ZUEC-POL 16122), 22 Feb 2009, and 3 specs (MZUSP 2399; ZUEC- POL 16128), 2 Jul 2009; 23 ° 10 ' 4 " S 41 ° 3 ' 6 " W, 105 m: 4 specs (MZUSP 2388; ZUEC-POL 16118), 21 Feb 2009, and 3 specs (MZUSP 2389; ZUEC-POL 16119), 2 Jul 2009; 23 ° 11 ' 28 " S 41 ° 0 ' 49 " W, 117 m: 8 specs (MZUSP 2391; ZUEC-POL 16121), 21 Feb 2009; 23 ° 12 ' 8 " S 40 ° 59 ' 35 " W, 142 m: 2 specs (MZUSP 2390; ZUEC-POL 16120), 2 Jul 2009. Additional material examined. Opisthodonta morena — Atlantic Ocean, Josephine Bank (36 ° 40.7 ' N 14 ° 15.5 ' W): 17 specs (ZMH P- 17193), coll. ' Meteor 9 c', station 120, 0 1 Jul 1967, det. G. Hartmann-Schröder, 1979. Opisthodonta mitchelli Kudenov & Harris, 1995 — USA, California, Santa Maria Basin, off Point Arguello (34 ° 30 ' 15 " N 120 ° 35 ' 34 " W), 54 – 63 m: 1 spec. (holotype, USNM 170919), coll. SAIC / Mbc BLM / MMS, R / V Diaphus DS, 11 Jul 1984, det. Kudenov & Harris, 1995; off Purisima Point (34 ° 46 ' 14 " N 120 ° 49 ' 58 " W), 91.5 – 123 m: 1 spec. (paratype, USNM 170920), coll. SAIC / Mbc BLM / MMS, R / V Diaphus DS, 23 Jul 1984, det. Kudenov & Harris, 1995.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF5FFC5FF68FF6AD1A9A40E.taxon	description	Description. Medium-sized, fragile body, specimens examined mostly anterior fragments, with few chaetigers after proventricle segments; largest fragment 2.6 mm long, 0.52 mm wide, with 26 chaetigers; body without pigmentation patterns, dorsally with transverse rows of tufts of cilia, at least on midbody (Fig. 13 B, D). Palps foliaceous, broader than prostomium, frequently ventrally folded (Figs 11 A; 12 A – B; 13 A). Prostomium oval to pentagonal, with 2 pairs of eyes in trapezoidal arrangement and 1 pair of anterior eyespots (Fig. 11 A); lateral antennae inserted in front of anterior pair of eyes, near anterior margin of prostomium, up to twice as long as combined length of prostomium and palps; median antenna inserted centrally, almost twice as long as lateral antennae (Figs 11 A; 12 A – B); nuchal organs as paired, transverse, dorso-lateral rows of cilia at posterior margin of prostomium (Fig. 12 A – B). Peristomium dorsally short, frequently covered by prostomium and chaetiger 1; dorsal peristomial cirri of approximately same size as median antenna, ventral peristomial cirri with approximately same size as lateral antennae or slightly longer (Figs 11 A; 12 A – B). Dorsal cirri of anterior chaetigers, specially of chaetiger 1, long and slender, sometimes conspicuously longer than median antenna (Fig. 11 A); dorsal cirri alternating long, almost twice as long as body width, and short, slightly longer than half body width at corresponding chaetiger (Figs 11 A; 12 A; 13 B); ventral cirri large, ovate, partially fused to parapodial lobes on anterior segments (Fig. 13 A, C); from proventricle segments onwards, ventral cirri short, conical, shorter than parapodial lobes and free from them (Fig. 12 C). Antennae, peristomial and dorsal cirri throughout similar, long and slender, with short cirrophores (Figs 11 A; 12 C; 13 B). Anterior body parapodia with ~ 20 – 25 falcigers each, decreasing to ~ 5 – 10 falcigers per parapodium from midbody onwards; falcigers with shafts and blades spinulated, blades with spines slightly distally directed, bidentate; on anterior body, 2 – 4 dorsalmost falcigers with longer blades, ~ 30 – 22 µm long, teeth of even size or distal tooth slightly larger, rounded space between teeth; blades of remaining falcigers of anterior parapodia ~ 17 – 13 µm long, subdistal tooth of same size or slightly larger than distal tooth (Figs 11 B; 12 D); on midbody parapodia, 1 – 2 dorsalmost falcigers with blades 22 – 20 µm long, blades of remaining falcigers ~ 15 µm long, subdistal tooth progressively larger and more hooked towards posterior body (Fig. 11 C). Dorsal simple chaetae only present on posteriormost parapodia, thin, slightly spinulated subdistally, bidentate, teeth minute, of even size, with rounded space between teeth (Fig. 11 D); ventral simple chaetae only present on posteriormost parapodia, sigmoid, bidentate, subdistal tooth larger (Fig. 11 E); dorsal and ventral simple chaetae sometimes present from anterior body, in juveniles. Anterior body parapodia with up to 4 aciculae each (Fig. 11 F), aciculae per parapodium diminishing towards posterior body, from midbody onwards only 1 acicula per parapodium (Fig. 11 G); aciculae progressively thinner towards posterior body, distally tapering, with rounded tips protruding from parapodial lobes (Fig. 12 D), more evidently on posterior body. Pharynx long and wide, through 8 – 12 segments, with large, conical to pyriform tooth near midlength or slightly anteriorly; proventricle through 7 – 8 segments, with ~ 23 muscle cell rows (Fig. 11 A).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF5FFC5FF68FF6AD1A9A40E.taxon	discussion	Remarks. Opisthodonta morena closely resembles O. mitchelli, from California (USA), but both can be differentiated mostly by posterior body features: in O. mitchelli aciculae have tips slightly bent, and falciger blades have a finer spinulation and the subdistal tooth conspicuously larger than the distal tooth, which resembles an enlarged spine in some chaetae; on the other hand, in O. morena all aciculae are straight (Fig 11 F – G), and the falciger blades have coarser spinulation and less pronounced difference in sizes between the teeth. Brazilian specimens of O. morena are virtually indistinguishible from those from close to the type locality (Josephine Banks, Atlantic Ocean). As the species is reported from nearly all over the world (see below), it is a possible case of a complex of sibling-species.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF5FFC5FF68FF6AD1A9A40E.taxon	materials_examined	Type locality. Atlantic Ocean: Portugal — Madeira Island	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF5FFC5FF68FF6AD1A9A40E.taxon	distribution	Distribution. Pacific Ocean: Australia (New South Wales). Indic Ocean: Australia (Western Australia), Red Sea. Mediterranean Sea. Atlantic Ocean: Madeira Island. First occurrence for the Brazilian coast.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF1FFCBFF68FE4AD10EA020.taxon	materials_examined	Material examined. Project ‘ REVIZEE´. State of Rio de Janeiro — 23 ° 09 ’ S 40 ° 56 ’ W, 257 m: 1 spec. (MZUSP 2442), 1 Mar 1998; 23 ° 20 ’ S 41 ° 22 ’ W, 110 m: 10 specs (1 spec., MZUSP 2439; 5 specs, MZUSP 2444; 1 spec., ZUEC-Pol 16093), 28 Feb 1998; 23 ° 26 ’ S 41 ° 15 ’ W, 146 m: 5 specs (1 spec., MZUSP 2440; 1 spec., ZUEC-Pol 16092; 2 specs, ZUEC-Pol 16173), 28 Feb 1998; 23 ° 29 ’ S 41 ° 09 ’ W, 266 m: 3 specs (MZUSP 2446), 28 Feb 1998; 23 ° 41 ’ S 41 ° 44 ’ W, 149 m: 3 specs (ZUEC-POL 16172), 17 Feb 1998; 24 ° 02 ’ S 43 ° 30 ’ W, 147 m: 4 specs (MZUSP 2445), 14 Feb 1998. State of São Paulo — 24 ° 07 ’ S 45 ° 51 ’ W, 147 m: 2 specs (MZUSP 2443), 9 Jan 1998; 24 ° 20 ’ S 44 ° 09 ’ W, 258 m: 1 spec. (ZUEC-POL 16171), 10 Jan 1998. Project ' Habitats '. 21 ° 9 ' 10 " S 40 ° 16 ' 7 " W, 101 m: 2 specs (MZUSP 2426), 7 Mar 2009, and 2 specs (MZUSP 2437; ZUEC-POL 16169), 21 Jul 2009; 21 ° 11 ' 1 " S 40 ° 28 ' 28 " W, 26 m: 1 spec. (ZUEC-POL 16168), 21 Jul 2009; 21 ° 12 ' 13 " S 40 ° 42 ' 25 " W, 15 m: 1 spec. (MZUSP 2408), 7 Mar 2009; 21 ° 14 ' 15 " S 40 ° 14 ' 8 " W, 66 m: 2 specs (MZUSP 2411), 8 Jul 2009; 21 ° 23 ' 3 " S 40 ° 15 ' 10 " W, 142 m: 3 specs (MZUSP 2428; ZUEC-POL 16157), 6 Mar 2009, and 8 specs (MZUSP 2438), 21 Jul 2009; 21 ° 23 ' 38 " S 40 ° 15 ' 37 " W, 88 m: 2 specs (MZUSP 2436; ZUEC- POL 16170), 21 Jul 2009; 21 ° 24 ' 43 " S 40 ° 25 ' 20 " W, 32 m: 1 spec. (ZUEC-POL 16140), 20 Jul 2009; 21 ° 34 ' 12 " S 40 ° 25 ' 32 " W, 29 m: 1 spec. (MZUSP 2406), 13 Mar 2009; 21 ° 42 ' 37 " S 40 ° 8 ' 58 " W, 147 m: 11 specs (MZUSP 2427; ZUEC-POL 16156), 10 Mar 2009, and 23 specs (MZUSP 2433; ZUEC-POL 16165), 7 Jul 2009; 21 ° 42 ' 53 " S 40 ° 10 ' 15 " W, 98 m: 1 spec. (ZUEC-POL 16155), 9 Mar 2009; 21 ° 43 ' 10 " S 40 ° 11 ' 30 " W, 72 m: 2 specs (ZUEC-POL 16164), 8 Jul 2009; 21 ° 44 ' 19 " S 40 ° 17 ' 15 " W, 50 m: 3 specs (MZUSP 2432; ZUEC-POL 16163), 8 Jul 2009; 21 ° 50 ' 3 " S 40 ° 6 ' 14 " W, 469 m: 1 spec. (MZUSP 2441), 28 Jun 2008; 21 ° 59 ' 4 " S 40 ° 25 ' 10 " W, 52 m: 1 spec. (MZUSP 2424), 25 Feb 2009; 22 ° 3 ' 38 " S 40 ° 6 ' 59 " W, 90 m: 2 specs (MZUSP 2431; ZUEC-POL 16162), 7 Jul 2009; 22 ° 3 ' 41 " S 40 ° 24 ' 8 " W, 56 m: 1 spec. (MZUSP 2421; ZUEC-POL 16153), 25 Feb 2009; 22 ° 3 ' 45 " S 40 ° 9 ' 59 " W, 75 m: 2 specs (MZUSP 2425), 25 Feb 2009; 22 ° 6 ' 20 " S 40 ° 43 ' 41 " W, 47 m: 1 spec. (MZUSP 2409), 17 Jul 2009; 22 ° 6 ' 55 " S 40 ° 38 ' 58 " W, 53 m: 14 specs (MZUSP 2417; ZUEC-POL 16150), 26 Feb 2009, and 4 specs (MZUSP 2435; ZUEC-POL 16167), 17 Jul 2009; 22 ° 8 ' 9 " S 40 ° 27 ' 27 " W, 65 m: 1 spec. (MZUSP 2418), 23 Feb 2009; 22 ° 11 ' 59 " S 40 ° 32 ' 7 " W, 68 m: 4 specs (MZUSP 2407; ZUEC-POL 16138), 15 Mar 2009; 22 ° 12 ' 18 " S 40 ° 14 ' 39 " W, 97 m: 1 spec. (ZUEC-POL 16139), 15 Mar 2009; 22 ° 12 ' 37 " S 40 ° 13 ' 18 " W, 100 m: 10 specs (MZUSP 2422; ZUEC- POL 16154), 24 Feb 2009, and 26 specs (MZUSP 2430; ZUEC-POL 16160), 5 Jul 2009; 22 ° 12 ' 31 " S 40 ° 14 ' 7 " W, 97 m: 1 spec. (ZUEC-POL 16142), 24 Jul 2009; 22 ° 12 ' 52 " S 40 ° 51 ' 12 " W, 52 m: 1 spec. (ZUEC-POL 16146), 26 Feb 2009; 22 ° 13 ' 44 " S 40 ° 32 ' 43 " W, 70 m: 2 specs (MZUSP 2410; ZUEC-POL 16141), 25 Jul 2009; 22 ° 17 ' 25 " S 40 ° 6 ' 36 " W, 143 m: 1 spec. (MZUSP 2423), 24 Feb 2009, and 1 spec. (ZUEC-POL 16161), 5 Jul 2009; 22 ° 17 ' 42 " S 40 ° 26 ' 59 " W, 104 m: 5 specs (MZUSP 2419; ZUEC-POL 16151), 23 Feb 2009, and 8 specs (MZUSP 2429; ZUEC- POL 16158), 4 Jul 2009; 22 ° 19 ' 32 " S 40 ° 37 ' 18 " W, 75 m: 4 specs (MZUSP 2414; ZUEC-POL 16147), 15 Mar 2009, and 5 specs (MZUSP 2416; ZUEC-POL 16149), 4 Jul 2009; 22 ° 23 ' 20 " S 40 ° 34 ' 56 " W, 110 m: 22 specs (MZUSP 2434), 25 Jul 2009; 22 ° 23 ' 38 " S 40 ° 20 ' 42 " W, 153 m: 4 specs (MZUSP 2420; ZUEC-POL 16152), 23 Feb 2009, and 1 spec. (ZUEC-POL 16159), 4 Jul 2009; 22 ° 46 ' 54 " S 41 ° 3 ' 33 " W, 78 m: 1 spec. (MZUSP 2412), 22 Feb 2009, and 1 spec. (MZUSP 2415), 2 Jul 2009; 22 ° 52 ' 1 " S 40 ° 57 ' 28 " W, 92 m: 2 specs (MZUSP 2413), 22 Feb 2009. Additional material examined. Opisthodonta russelli — Venezuela, Parque Nacional Morrocoy, on Thalassia testudinum, 0.5 m: 7 specs (holotype, MNCN 16.01 / 6063; paratypes, MNCN 16.01 / 6064 - 6069). Opisthodonta sp. B sensu Uebelacker (1984) — USA, North Carolina, Beaufort (34 ° 19 ' 14 " N 75 ° 55 ' 48 " W), 130 m: 1 spec. (USNM 51071), coll. J. H. Day, 0 6 Apr 1965, det. J. M. Uebelacker; Gulf of Mexico, Florida (29 ° 47 ' 59 " N 86 ° 09 ' 28 " W), 45 m: 1 spec. (USNM 55824), coll. R / V Columbus Iselin, Jun 1975, id. J. M. Uebelacker.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF1FFCBFF68FE4AD10EA020.taxon	description	Description. Medium-sized, fragile body, specimens examined mostly anterior fragments with few chaetigers after proventricle and without appendages; largest specimen examined (MZUSP 2495) 9.55 mm long, 0.84 mm wide, with 49 chaetigers (Table 2); body without pigmentation patterns, dorsally scattered with tufts of cilia as short, transverse rows, at least on midbody (Figs 15 A, C, E; 16 D). Palps foliaceous, broader than prostomium, triangular (Figs 14 A; 15 A – D). Prostomium oval to subpentagonal, with 2 pairs of eyes in close trapezoidal arrangement and 1 pair of anterior eyespots (Fig. 14 A); lateral antennae inserted in front of anterior pair of eyes, near anterior margin of prostomium, up to twice as long as combined length of prostomium and palps; median antenna inserted centrally, almost twice as long as lateral antennae; nuchal organs as dense row of cilia at posterior margin of prostomium, more conspicuous dorso-laterally (Fig. 15 A, C – D). Peristomium shorter than anterior chaetigers; dorsal peristomial cirri as long as lateral antennae or slightly longer, ventral peristomial cirri 2 / 3 length of dorsal peristomial cirri. Anterior body dorsal cirri variable in length, shorter cirri slightly shorter than body width at corresponding chaetigers, longer cirri up to 3 times length of shorter cirri (Figs 14 A; 15 A, C); dorsal cirri progressively thinner towards posterior body, whip-shaped, nearly of same length as anterior body dorsal cirri; anterior body ventral cirri foliaceous, wide, partially fused to parapodial lobes, at least as long as parapodial lobes, with mamiliform tips (Figs 15 B; 16 A – B); ventral cirri progressively smaller, conical to ovate towards posterior body (Figs 15 B; 16 C). Antennae, peristomial and dorsal cirri throughout similar, long and slender, with conspicuous cirrophores (Figs 14 A; 15 A – D). Anterior body parapodia with 1 – 7 dorsalmost compound chaetae spiniger-like, with smooth shafts; blades long, basally inflated and distally inconspicuously bifid, 100 – 42 Μm long (Fig. 14 B – C); spiniger-like chaetae absent from midbody chaetigers (Fig. 15 A – C). Anterior body parapodia with ~ 20 – 32 falcigers each, decreasing to ~ 6 – 14 falcigers per parapodium from midbody; falcigers with weakly spinulated shafts (Figs 14 B – D, F – G; 16 E – I); blades bidentate, subdistal tooth larger than distal tooth; blades with dense spinulation forming a hood, translucent under optical microscopy, usually leaving uncovered only tips of teeth on anterior body and on dorsalmost chaetae of each parapodium throughout (Figs 14 B – D; 16 E – G), teeth more conspicuous from midbody (Figs 14 F – G; 16 H – I); blades of anterior body falcigers with dorsoventral gradation in length, 26 – 12 Μm long; posterior body falcigers of two different types: dorsalmost falcigers with distinctly heterogomph shafts, blades bidentate, subdistal tooth larger than distal tooth, with hood shorter than on anterior body falcigers, blades ~ 20 – 10 Μm long (Fig. 14 F); ventralmost falcigers with shafts progressively shorter and stouter ventralwards, subtly heterogomph, blades bidentate, subdistal tooth larger than distal tooth, with more conspicuous difference in size between teeth, spinulation not forming hood (Figs 14 G; 16 H – I). Dorsal simple chaetae thin, capillary, apparently finely bidentate distally, absent on most specimens analysed; ventral simple chaetae not observed. Anterior body parapodia with 3 – 7 aciculae each, diminishing in number towards posterior body, posterior parapodia with 1 – 3 aciculae each; aciculae with tips sometimes protruding from parapodial lobes, distally rounded, with subdistal crown of short spines (Fig. 14 E); aciculae progressively thinner towards posterior body. Pharynx long and wide, through 13 – 17 segments, with large, pyriform tooth with acute tip near midlength or slightly anteriorly, usually located laterally; proventricle wide, through 5 – 8 chaetigers, with ~ 30 – 35 muscle cell rows (Fig. 14 A).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF1FFCBFF68FE4AD10EA020.taxon	discussion	Remarks. The original description of O. russelli was based only on anterior fragments (San Martín et al. 2009). Thus, our description of mid- and posterior body characters (mostly from chaetae) is new for this species. A complete comparison with the most similar congeners may be found in San Martín et al. (2009).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF1FFCBFF68FE4AD10EA020.taxon	materials_examined	Type locality. Venezuela — Morrocoy National Park (Atlantic Ocean).	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
A5678797FFF1FFCBFF68FE4AD10EA020.taxon	distribution	Distribution. Atlantic Ocean: Venezuela; Belize. First record for the Brazilian coast.	en	Fukuda, Marcelo V., Nogueira, João M. M., Martín, Guillermo San (2015): Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species. Zootaxa 3936 (4): 507-537, DOI: 10.11646/zootaxa.3936.4.3
