Bradabyssa tzetlini Salazar-Vallejo 2017, n. comb.

Bradabyssa tzetlini (Jirkov & Filippova in Jirkov, 2001) n. comb.

Figure 44

Brada tzetlini Jirkov & Filippova, 2001: 356 –357, Figs 1–5.—Oug et al. 2011: 14, Figs 1–4 (reprod. from Jirkov & Filippova, 2001).

Type material. Norwegian Sea. Syntype (HDMSU 21.07.1957), R.V. Sevastopol, Cruise 5, Sta. 1116 (63.0° N, 02.25° E), 950 m, 21 Aug. 1957. Syntype (HDMSU 27.09.1958), dried-out, R.V. Sevastopol, Cruise 10, Sta. 1702 (66.38° N, 04.59° E), 1125 m, 27 Sep. 1958 (cephalic cage 1.5 mm long, 2 notochaetae and 2 neurochaetae in chaetiger 1). Syntype (HDMSU 15.10.1958), R.V. Sevastopol, Cruise 10, Sta. 1766 (65.13° N, 00.10° E), 730 m, 15 Oct. 1958, Agassiz trawl (two anterior fragments of mature females, partly dehydrated; oocytes about 125 µm). Syntype (HDMSU 4.11.1959), dried-out, R.V. Sevastopol, Cruise 15, Sta. 2444 (69.2° N, 00.08° E), 1000 m, 4 Nov. 1959 (parapodia with 4 notochaetae and 4 neurochaetae per ramus). Syntype (HDMSU 30.06.1978), R.V. Tunetz, Cruise 105, Sta. 16 (72.5° N, 00.14° E), 960 m, 30 Jun. 1978 (complete, slightly swollen anteriorly, 13 mm long, 3 mm wide, cephalic cage 2 mm long (5 notochaetae, 4 neurochaetae), 30 chaetigers, gonopodial lobes in chaetiger 5, each digitate with tip black, posterior end with anus dorsal, anus with a thick black muscular ring, without anal cirri. Notochaetae 4–5, in transverse series, neurochaetae 4–5, in oblique series; notochaetae about 1/3 as long as body width, 5 transverse series of dorsal papillae).

Description. Better preserved syntype (HDMSU 21.07.1957) broken in two fragments; body whitish, papillae light brown (Fig. 44A), ventrally flat, blunt at both ends; 24(11+13) mm long, 4 mm wide, cephalic cage 1.8 mm long, 34(13+21) chaetigers. Papillae covered by fine sediment grains. Papillae very long, larger dorsally, arranged in 5–6 transverse series, shorter ventrally (Fig. 44B); posterior chaetigers with larger papillae, basally swollen, globular with long tip. Smaller syntype (HDMSU 30.06.1978) 13 mm long, 3 mm wide, cephalic cage 2 mm long, 30 chaetigers.

Anterior end not dissected. Cephalic cage chaetae broken; in another syntype (HDMSU 30.06.1978) chaetae 2.0 mm long. Only chaetiger 1 involved in cephalic cage; chaetae arranged in short lateral series, with 5 notochaetae and 4 neurochaetae per bundle.

Anterior margin of first chaetiger papillated, papillae short, rounded, eroded. Anterior chaetigers without especially long papillae. Chaetal transition from cephalic cage to body chaetae abrupt; aristate neurospines present from chaetiger 2. Gonopodial lobes in chaetiger 5 (Fig. 44B, C), blunt, digitate, tip slightly darker.

Parapodia well developed, lateral (Fig. 44D). Median neuropodia ventrolateral. Notopodia and neuropodia close to each other. Notopodia with chaetal lobe short, rounded, with 3–4 long papillae, longest about 1/3 as long as notochaetae.

Median notochaetae arranged in short transverse series, most notochaetae multiarticulate capillaries with articles short basally and medially, become long distally (Fig. 44E); about 4–5 notochaetae per bundle, about half as long as body width. Neurochaetae multiarticulate capillaries in chaetiger 1; posterior chaetigers with aristate neurospines, arranged in short transverse series, 4 per bundle. Each neurospine with short rings basally and medially, distally tapering, hyaline with long falcate mucro (Fig. 44F).

Posterior end rounded, truncate; pygidium with anus terminal, thick, anal cirri absent. Oocytes in a mature anterior fragment (HDMSU 15.10.1958), about 125 µm.

Remarks. Bradabyssa tzetlini (Jirkov & Filippova in Jirkov, 2001 ) n. comb. belongs to a group of species having 28–33 chaetigers and dorsal papillae with adhering sand particles, which includes B. pluribranchiata (Moore, 1923) n. comb. and B. setosa (Verrill, 1873) n. comb. However, B. tzetlini differs from these other species by having gonopodial papillae with pale stems and dark tips, whereas the other species possess completely pale ones.

Distribution. Scandinavian waters, Norwegian Sea, in 700–1200 m water depth.