Berkeleyia abyssala Blake, 2017, new species

Berkeleyia abyssala new species

Figures 2 F–G, 3

Haploscoloplos kerguelensis: Hartman 1967 (in part: Sta. 311, 1063). Not McIntosh 1885.

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).

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, 3A); without eyespots; nuchal organs on posterolateral margin of prostomium (Fig. 2 F). Peristomium achaetous, indistinctly separated from prostomium and setiger 1 (Figs. 2 F, 3A). 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, 3A); each branchia short, subtriangular (Fig. 3 B).

Etymology. The epithet is derived from abyssus, Latin for deep sea.

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.

Distribution. Antarctic and subantarctic seas, abyssal depths of 3111–4176 m.