Brada incrustata Stop-Bowitz 1948

Brada incrustata Støp-Bowitz, 1948

Figure 5

Brada incrustata Støp-Bowitz, 1948a: 44 –47, Fig. 12.— Støp-Bowitz 1948b: 44 –46, map.— Jirkov & Filippova 2001: 352 –353, Figs 1–3.— Oug et al. 2011: 15, Figs 1–c (repeated from Støp-Bowitz, 1948a).

Brada inhabilis.— Malmgren 1867: 194 (partim).— Haase 1915: 206 –209, Textfig. 9 (partim, non Rathke, 1843).

Type material. Northwestern European Arctic Ocean. Lectotype (ZMUB 18605), Norwegian North Atlantic Expedition, no further data, previously identified as B. granulata by A. Hansen. Two paralectotypes (ZMUB 2195), Norwegian North Atlantic Expedition, Sta. 374 (78°16' N, 11°17' E), Advent Bay, Spitzbergen, Norway, no further data (42–47 mm long, 7–9 mm wide, cephalic cage chaetae missing, 24–25 chaetigers). One paralectotype (ZMUB 2198) dark, mature female, previously dissected, damaged, with many pale epizoic anthozoids, Danesgat, Spitzbergen Expedition, sandb. Med sten + ler., 37 m, Sep. 1861, Malmgren, coll. (35 mm long, 8.5 mm wide, cephalic cage chaetae broken, 25 chaetigers; oocytes about 125 µm).

Description. Lectotype (largest specimen, ZMUB 18605) pale, body truncate in both ends, medially swollen (Fig. 5A); 49 mm long, 8 mm wide, cephalic cage 1.0 mm long (a single neurochaetae), 24 chaetigers. Papillae forming 2–3 transverse ridges per segment, anteriormost and posteriormost segments with all ridges fused; all papillae conical, long. Dorsally, papillae with adhering sediment grains forming ridges as long as whole chaetiger, leaving narrow intersegmental furrows; ventrally papillae adhering sediment without forming ridges.

Anterior end morphology observed in damaged paralectotype (ZMUB 2198). Cephalic hood not exposed. Prostomium low pale cone; eyes not seen. Caruncle triangular, narrow, continued posteriorly almost reaching posterior branchial plate margin. Palps thick, smooth, pale; palp keels rounded, low. Lateral lips dark, well developed (Fig. 5B). Dorsal lip triangular, reduced. Ventral lip reduced.

Branchiae all cirriform, thick, blunt, sessile on branchial plate, arranged in a single marginal row, slightly separated in two lateral groups, without interbranchial lobes, each with 4 filaments. Larger branchiae as thick as palps, about 2/3 as long as palps. Nephridial lobes not seen.

Cephalic cage chaetae very thin, broken, only remaining neurochaetae as long as 1/49 body length, or as long as about 1/8 body width. Chaetiger 1 involved in cephalic cage; chaetae arranged in very short lateral series; probably 2 notochaetae and 2 neurochaetae per side (most missing).

Anterior dorsal margin of first chaetiger triangular, directed ventrally, papillated; papillae small, abundant with adhering sediment particles. Anterior chaetigers without especially long papillae. Chaetigers 1–3 of similar size; notopodia in chaetiger 2 slightly larger than the others. Chaetal transition from cephalic cage to body chaetae abrupt; chaetiger 2 with neurohooks (broken). Gonopodial lobes small, slightly dark, present in chaetiger 5 (Fig. 5C).

Parapodia lateral, well developed; median neuropodia ventrolateral. Notopodia and neuropodia close to each other (Fig. 5D). Notopodia elongate conical lobes with single large infra-chaetal papillae, continued to the end of body. Neuropodia larger rounded lobes, bordered anteriorly by transverse ridges and a variable number (2–5) of variably fused postchaetal papillae.

All notochaetae multiarticulate capillaries, articles irregular, short basally, longer medially and longest distally (Fig. 5E); median notochaetae arranged in tufts, about 2–3 per ramus, as long as 1/5 body width. Neurochaetae multiarticulate capillaries in chaetiger 1. Aristate brown neurospines from chaetiger 2 (most with broken tips), arranged in oblique short series, 4–5 per ramus. Each neurospine with short anchylose articles basally; medially, subdistally flat, curved, rings longer, gently falcate (Fig.5F); smaller neurospines with acute tips, and recurved, stiff hood (Fig. 5G).

Posterior end rounded, truncate; pygidium with anus terminoventral, vertical slit; anal cirri absent.

Variation. Adult specimens 35–47 mm long, 7–9 mm wide, 24–25 chaetigers.

Remarks. Brada incrustata Støp-Bowitz, 1948 is unique in the genus because it has a continuous, dorsal sediment crust, which is usually formed from 1–2 large transverse blocks per segment.

Støp-Bowitz (1948a:44) proposed Brada incrustata as a new name, apparently to replace B. inhabilis recorded by Malmgren, 1867, as if it was a junior homonym of B. inhabilis (Rathke, 1843). This was not the case because Malmgren (1867:194) indicated he was following Rathke and not proposing a new species. Consequently, B. incrustata must be regarded as a new species, instead of a replacement name, and the type specimens must be regarded as syntypes (ICZN, Arts. 72.4.1, 73.2), and a lectotype has been designated from those available syntypes to fix the species definition (ICZN, Art. 74). Unfortunately, the label data of the lectotype herein selected (ZMUB 18605) does not indicate locality, only that it was part of the Norwegian North Atlantic Expedition, and that it was identified as B. granulata by Hansen (1882). Hansen (1882) recorded the species from several stations: 270, 323, 326,275, 338, and from Røst, Norway. Støp-Bowitz (1948a:45) indicated that the species was found off Spitsbergen, and these stations were made between the Norwegian and the Barents Sea, near Spitsbergen.

Distribution. Arctic waters, recorded from several localities in 225–408 m, mostly in clay sediments.

Paralectotype (ZMUB 2198), head (branchiae and palps removed; Br: branchial scar, LL: lateral lip, PS: palp scar). C. Neotype, anterior end, ventral view (arrows point togonopodial lobes). D. Same, chaetigers 20–22, left parapodia, dorsolateral view. E. Paralectotype (ZMUB 2195), chaetiger 12, left parapodium, basal, medial and distal notochaetal regions. F. Same, chaetiger 19, left parapodium, neurochaetal distal regions (inset: neurochaetal tip). G. Same, smallest neurochaetal tip, distal piece covered by ephemeral hood. Scale bars: A: 5.3 mm, B: 0.6 mm, C: 1.9 mm, D: 1.5 mm, E: 50 µm, F: 80 µm, G: 30 µm.