New Species of Scalibregmatidae (Annelida) from Slope and Abyssal Depths off Eastern Australia Author Blake, James A. text Records of the Australian Museum 2023 Rec. Aust. Mus. 2023-05-17 75 3 271 298 http://dx.doi.org/10.3853/j.2201-4349.75.2023.1827 journal article 10.3853/j.2201-4349.75.2023.1827 2201-4349 10414024 7D3BDF25-010F-41A4-AD15-763C3F067D8A Axiokebuita australis sp. nov. urn:lsid:zoobank.org:act: C93CC779-84C1-4FC0-8252-FEE01BBA2968 Figs 3–4 Holotype : eastern Australia , continental slope off Tasmania, Freycinet Marine Park , RV Investigator , Sta. 011, coll. 19 May 2017 , box core, 41.721°S 149.125°E , 2793 m ( AM W.52681) . Paratypes (2): same data as holotype (1, AM W.53989); abyssal plain off southeastern Victoria , East Gippsland Marine Park , RV Investigator , Sta. 033, coll. 24 May 2017 , Brenke Sled, distance 2.6 km , 38.521°S 153.213°E 4107 m to 38.498°S 150.207°E 4064 m , dissected in part for DNA (1, AM W.52695 ) . Description . All three specimens complete: holotype (AM W.52681) with 22 setigers, 10. 55 mm long and about 1.8 mm wide; paratype from Sta. 011 (AM W.53989) with 19 setigers, 8 mm long and 2 mm wide; paratype (AM W.52695) from Sta. 033 complete, but damaged and in two parts, with 19 setigers, about 6 mm long, about 1.2 mm wide (posterior section removed for DNA). Body thick, sausage-shaped; more or less rectangular in cross section ( Fig. 3A, C ), without dorsal or ventral grooves or ridges along body. Segments with one or two rows of elevated pads across dorsum; setigers 1–4 with a biannulate pattern ( Fig. 4A ); most of body with uniannulate segments; ventrally, each anterior and middle segment with one to four annulated rows, these narrow, with separate raised pads indistinct, appearing more or less as single elevated ridge; posteriorly ventral surfaces with a single row of raised pads more or less continuous with dorsal rows ( Fig. 3C, D ). Colour in alcohol light tan with no pigmentation. Figure 3 . Axiokebuita australis sp. nov. ( A ) Anterior two thirds of holotype, lateral view; ( B ) detail of pre-setiger region of same; ( C ) entire paratype in dorsolateral view; ( D ) posterior end, right lateral view. A, B, holotype (AM W.52681); C, D, paratype (AM W.53989). All stained with Shirlastain A. Figure 4 . Axiokebuita australis sp. nov. ( A ) anterior end, dorsal view; ( B ) setiger 9, anterior view.A, paratype (AM W.53989); B, holotype (AM W.52681). Prostomium pentagonal in shape ( Figs 3A, B , 4A ), straight across anterior end with two thick lateral horns arising from narrow subterminal sides ( Figs 3A, B , 4A ), followed by long curving borders meeting mid-dorsally; eyes absent, nuchal organs not observed. Peristomium irregularly encompassing prostomium dorsolaterally ( Figs 3A, B , 4A ) and surrounding mouth ventrally; proboscis emergent, with numerous elongate lobes surrounding oral opening ( Figs 3B , 4A ); neck organs observed on paratype (AM W.52695) as a pair of swellings ventrolateral on enlarged oral area; these obscured on holotype and other paratype due to ventral curvature and compression of entire pre-setiger area. Parapodia reduced to blister-like swellings throughout, with noto- and neurosetae arising from notch on posterior sides. Notopodia with single short, oval to rounded postsetal lamella, this less conspicuous in posterior setigers; neuropodia with an elongate, fingerlike lamella; both lamellae from setiger 2 or 3 continuing to posterior end ( Fig. 4B ). Setae all thin capillaries in spreading fascicles throughout; furcate setae not observed. Notosetae long, with up to 35–45 per fascicle. Pygidium a simple plate composed of 6–8 thickened lobes surrounded anal opening ( Fig. 3D ). Remarks . Axiokebuita australis sp. nov. is most similar to A. millsi , the type-species, in lacking papillated pygidial lobes. Specimens of A. millsi from off New England in bathyal depths were observed as part of a separate study (Blake in preparation) to have a fusiform-shaped body, two large non-papillated lobes around the anal opening, and 2–3 rows of annulated pads along the body; these observations agree with the published observations of Pocklington and Fournier (1987) from off Nova Scotia. In contrast, A. australis sp. nov. has a sausage or grub-shaped body, 6–8 small lobes around the anus, and two annulated rows of pads on setigers 1–4 but only a single row along the rest of the body. Etymology . The epithet is from the Latin australis , in reference to the Australian and Southern Hemisphere location of this species. Biology . Holotype (AM W.52681) and paratype (AM W.53989) with numerous oocytes in coelom measuring 80–100 µm in diameter. Distribution . Continental slope and abyssal plain off SE Australia , Tasmania and Victoria , 2793–4064 m .