Boudemos paulinae, Watson & Gunton & Kupriyanova, 2024

Watson, Charlotte, Gunton, Laetitia M. & Kupriyanova, Elena K., 2024, Three new species of bacterivorous Chrysopetalidae and Microphthalmidae (Annelida) inhabiting a whale fall off eastern Australia, Records of the Australian Museum 76 (5), pp. 249-264 : 255-256

publication ID	https://doi.org/10.3853/j.2201-4349.76.2024.1905
persistent identifier	https://treatment.plazi.org/id/A17487D2-FFCC-0A2F-FED2-F9AAFD24FD78
treatment provided by	Felipe
scientific name	Boudemos paulinae
status	sp. nov.

Treatment

Boudemos paulinae sp. nov.

urn:lsid:zoobank.org:act:0D045480-D246-41C1-B360-711E154ECF7D

Fig. 2A–D View Figure 2

Boudemos sp. — Georgieva et al., 2023, east coast of Australia.

Material examined

Holotype. AM W.55400 (body length 1.8 mm for 20 segments, width 0.7 mm, mature gametes 0.04 mm in diameter present).

Paratypes. AM W.55401 (approximately 100 mostly broken specimens with 6–20 segments; only 2 entire specimens include 7E, L: 0.56 mm, W: 0.35 mm; 12E, L: 0.9 mm, W: 0.55 mm). MAGNT W032913 About MAGNT (1 specimen) .

DNA vouchers. NHM_240E.

Type locality. A pilot whale skeleton off Byron Bay, NSW, Australia.

Description. Body very small, elongate, slightly broader anterior end, narrowed posteriorly. Preserved material whitish, covered in white bacteria. Erect ‘spiky’ notochaetal fans interlocking over dorsum ( Fig. 2A–B View Figure 2 ). Prostomium anterior edge half rounded with prostomial structures only visible in ventral view: two small digitiform lateral antennae inserted towards posterior prostomial margin; two small, glandular, ovoid, fused palps, mid position at posterior base of prostomium; eyes absent ( Fig. 2B–C View Figure 2 ).

Short, barrel-shaped muscular pharynx with coarse internal septa, terminal mouth papillae present. Two stylets composed of dark brown, toothed, terminal platelets facing outwards; each connected posteriorly to individual elongate, hyaline structures with a mid-way flange.

Achaetous segment I with one pair of dorsal and ventral tentacular cirri. Dorsal cirri pair, slightly longer, more robust than ventral pair, characteristically project out wing-like, dorso-laterally from anterior end; ventral cirri pair on small cirrophores immediately adjacent to palps ( Fig. 2B–C View Figure 2 ). Notopodia of segment II with notochaetae and pair of longer dorsal cirri; neuropodia with ‘whip-like’ spinigerous neurochaetae, ventral cirri absent. Segment III biramous, notopodia with notochaetae, longer dorsal cirri, neuropodia with slender falcigerous neurochaetae and slender ventral cirri ( Fig. 2A, C View Figure 2 ). Segment IV onwards down body similar to segment III, with medium-size dorsal cirri ( Fig. 2A View Figure 2 ) and slender ventral cirri ( Fig. 2B View Figure 2 ).

Notopodia in mid-body segments with notochaetal fascicle spread out in erect fan-like arrangement ( Fig. 2A View Figure 2 ). Long, slender, simple notochaetae narrow distally, ending in rounded, almost truncate distal tip; with two rows of serrations. Fascicle comprises longer notochaetae appearing slightly flattened mid-chaetae and marginal serrations spaced far apart; shorter notochaetae more rounded in section with finer serrations ( Fig. 2D View Figure 2 ). Notochaetae number 25–30. Dorsal cirri robust, similar length to longer than fascicle with low cirrophores. Dense ciliary patches present inter-ramally and dorsally ( Fig. 2D View Figure 2 ). Notochaetae chambered internally with horizontal striae.

Mid-body neuropodia plus neurochaetae longer than notopodia, ventral cirri insert sub-distally mid-neuropodia, posteriorly directed, fusiform, cirrophores barely observable ( Fig. 2B View Figure 2 ). Acicular lobe pronounced, pointed with small pre-chaetal lobe, with long, robust, single neuroaciculae; neurochaetae insert below aciculae. Neurochaetae compound unidentate falcigers, articles slender with small, curved distal tips, dense, fine serration starting immediately below tip; bifid heterogomph shafts, chambered internally with horizontal striae. Neurochaetae inserted in two loosely defined groups, upper 3-4 with longer blades, lower blades gradually shorter and wider; no neurochaetal shaft joint swelling or neurochaetal blade groove observed. Neurochaetae number 15–20.

Entire pygidium rounded with two anal cirri. Pygidia missing on most specimens with evidence common of part regeneration of posterior segments.

Etymology. Boudemos paulinae sp. nov. is named in honour of the first author’s mother, Pauline Cleary, who imbued in her from an early age a love of the sea and a sense of critical regard. Pauline’s ashes are spread at sea offshore from Byron Bay in the vicinity of the whale fall and the abundant life cycle it sustains.

Diagnosis. Smaller sized species (<2 mm) compared to its congeners (35–40 mm) and exhibits stylet jaw and notochaetal morphology observed in juveniles of the species Boudemos flokati .

Diagnostic remarks. Previously described free-living species Boudemos flokati and B. ardabilia are large-bodied, B. flokati measures 40 mm for 91 segments and the size of B. ardabalia ranges from 5 to 35 mm and the number of segments from 28 to 82. In contrast, ovigerous females of B. paulinae sp. nov. reach a length of 1.8 mm. The two previously described species also possess distinct swelling at the neurochaetal joint and neurochaetal blades with a groove. Adult notochaetae are thick and robust with frayed spinule ornamentation (Dahlgren et al., 2004; Watson et al., 2016). Adults of B. paulinae sp. nov. lack these chaetal characters.

There are no new morphological characters in B. paulinae sp. nov., but their adults (gamete-bearing specimens) possess characters documented for juveniles of B. flokati . These include very slender simple spinous-like notochaetae with two rows of spinelets, with the shorter chaetae being more rounded in cross-section (Dahlgren et al., 2004, fig. 6c, cf. Fig. 2D View Figure 2 ). A pair of stylet jaws in adults of B. paulinae sp. nov. are separated and face outwards with serrated, dark brown terminal platelets and posterior, elongate, hyaline structures bearing a mid-way flange. The same jaw morphology has been described in benthic post-larvae of B. flokati , while jaws are lost in adults (Dahlgren et al., 2004; Watson et al., 2016, fig. 8A–C). A similar stylet jaw structure is observed in post-larvae of Vigtorniella zakai ( Kiseleva, 1992) , with the stylet bearing typical sclerotised serrate tips (Watson & Faulwetter, 2017, fig. 21A–B). Entire jaws in V. zakai are present in larvae known for extended feeding in the plankton, while only the terminal platelet jaw is retained in meiofaunal adults that settle in high densities on microbial mats in flocculent sediments (Watson et al., 2016).