Bradabyssa bransfieldia Salazar-Vallejo 2017, n. comb.

Bradabyssa bransfieldia (Hartman, 1967) n. comb.

Figures 14, 15

Brada bransfieldia Hartman, 1967: 120 –121, no figs.— Hartman 1978: 167 –168, Fig. 19a–c (redescr.).— Rozbaczylo 1985: 158.— Detinova 1993: 100.

Ilyphagus cristatus Hartman, 1978: 173, Fig. 23a–c (new syn,).

Type material. Antarctica: Four “ Holotype ” specimens of Brada bransfieldia, one herein designated as lectotype (USNM 55542) and twenty-three as paralectotypes (USNM 1422476), off the South Shetland Islands, USNS Eltanin, Sta. 138 (62°00' S, 61°09' W → 62°05' S, 61°08' W), 1437 m, 8 Aug. 1962. Holotype of Ilyphagus cristatus (USNM 46824), and paratype (USNM 46825), Weddel Sea, USCGC Glacier, Cruise 1, Sta. 1 (74°07' S, 39°38' W), 650 m, 6 Feb. 1968, J.S. Rankin, coll. (paratype damaged; 23 mm long, 2 mm wide (2.2 mm in widest region), cephalic cage 2.5 mm long, 35 chaetigers).

Additional material. One anterior fragment (USNM 56659), off the South Shetland Islands, USNS Eltanin, Sta. 418 (62°39' S, 56°10' W), 426– 311 m, 2 Jan. 1963 (42 mm long, 3 mm wide, cephalic cage broken, 1.5 mm long, 34 chaetigers). Seven anterior and one posterior fragments (USNM 56660), damaged, Bransfield Strait, USNS Eltanin, Sta. 428 (62°41' S, 57°51' W), 662–1120 m, 5 Jan. 1963 (one anterior fragment of mature female, oocytes in varying sizes, larger ones 200 µm). Two anterior and one median fragment (USNM 56661) damaged, Bransfield Strait, USNS Eltanin, Sta. 432 (62°52' S, 59°27' W), 935– 884 m, 7 Jan. 1963 (anterior fragments 34–45 mm long, 2.0– 2.5 mm wide, cephalic cage 1.5–2.0 mm long, 32–34 chaetigers; gonopodial lobes in chaetiger 5).

Description. Lectotype (USNM 55542) 46 mm long, 2 mm wide, cephalic cage 2 mm long, 66 chaetigers. Posterior body region darker, cylindrical, slightly expanded in median segments, tapered afterwards (Fig. 14A). Integument shiny, finely papillated, appears granulose. Body papillae minute, a few larger dorsal papillae, especially on anterior chaetigers, arranged in 4–5 transverse series, eroded in most specimens (Fig. 14B), better preserved in a few others (Fig. 15A, B); without tunic or sediment particles.

Anterior end previously dissected laterally in lectotype; details based on paralectotypes with anterior end exposed (USNM 55543). Cephalic tube short, made of a single ring, margin smooth. Prostomium low cone, eyes not seen. Caruncle well developed, reaches posterior margin of branchial plate (Fig. 14C). Palps thick, short, palp keels rounded, low, slightly darker.

Branchiae cirriform, about 36 filaments per side, longer than palps. Nephridial lobes not seen.

Cephalic cage present, chaetae as long as body width (1.5 times longer in USNM 46824). Only chaetiger 1 involved in cephalic cage; chaetae arranged in short dorsolateral series, two chaetae per ramus (7–8 in USNM 46824, Fig. 15B).

Anterior dorsal margin of first chaetiger papillated, papillae tiny. Anterior chaetigers without especially long papillae. Chaetigers 1–3 of similar length, chaetiger 1 displaced dorsally. Chaetal transition from cephalic cage to body chaetae abrupt; neurospines present from chaetiger 2. Gonopodial lobes in chaetiger 5, pale short rounded.

Parapodia poorly developed, chaetae emerge from body wall (Figs 14D, 15C). Median neuropodia ventrolateral. Notopodia and neuropodia close to each other. Notopodia reduced, no longer papillae associated. Neuropodia better developed, rounded muscular lobes, smooth, without papillae.

Median notochaetae in tufts, most notochaetae missing, those remaining multiarticulate capillaries, articles short basally, long medially and distally (Fig. 14E), 4–5 per ramus, about half as long as body width. Neurochaetae aristate neurospines from chaetiger 2, 4 per ramus, arranged in transverse series (Figs 14F, 15D), straight to slightly curved.

Posterior end missing in type material, observed in non-type specimen (USNM 56660); tapered to rounded lobe, pygidium with anus dorsoterminal, anal cirri absent.

Variation. Paratypes of B. bransfieldia 17–25 mm long, 1–2 mm wide, cephalic cage 2 mm long, 25–31 chaetigers; all with gonopodial lobes in chaetiger 5. Other specimens 23–45 mm long, 2.0–3.0 mm wide, cephalic cage 1.5–2.5 mm long, 32–35 chaetigers.

Remarks. The original description of B. bransfieldia was brief and lacks illustrations (Hartman 1967); it was later redescribed and one parapodium and chaetae were illustrated (Hartman 1978). Although Hartman stated that the holotype was deposited in the Allan Hancock Foundation (AHF), there is a vial labeled “ holotype ” in the National Museum of Natural History (USA). However, this “ holotype ” contains four anterior fragments, which become syntypes, one of which has been selected herein as a lectotype and the rest become paralectotypes. The AHF collection is now housed in the Natural History Museum of Los Angeles, and the single bottle labeled as Brada bransfieldia includes one specimen of Fauveliopsis challengeriae, which is therefore definitely not the holotype of B. bransfieldia.

After the examination of the type material of Ilyphagus cristatus (Holotype, USNM 46824), I concluded that it shares most morphological features with B. bransfieldia, and although it is better preserved, or at least its body papillae are only slightly eroded, and its cephalic cage chaetae are not broken, it is herein regarded as a junior synonym.

Bradabyssa bransfieldia (Hartman, 1967) n. comb. resembles B. antarctica (Hartman, 1978) n. comb. because both have long, cylindrical bodies. As indicated above, they differ because B. bransfieldia has dorsal papillae of two different sizes, whereas in B. antarctica they are of a similar size. Furthermore, B. bransfieldia has more abundant notochaetae with short articles basally, whereas in B. antarctica they are fewer with medium-sized articles basally.

Distribution. South Shetland Islands, Weddell Sea, and Bransfield Strait, off the Antarctic Peninsula, Antarctica, in 311–4758 m.