Bradabyssa villosa Salazar-Vallejo 2017, n. comb.

Bradabyssa villosa (Rathke, 1843) n. comb., restricted

Figure 45

Siphonostoma villosum Rathke, 1843: 215 –218, Pl. 11, Figs 11–12.—Grube 1851: 16–17.

Brada villosa.—Sars 1873: 261 (n. comb.).—Théel 1879: 53.—Fauvel 1907: 22–23.—Moore 1908: 357.—Fauvel 1909: 6–7.—Haase 1915: 203–206, Textfig. 8 (partim).—Chamberlin 1920: 22.—McIntosh 1915: 104–106, Pl. 95, Fig. 12, Pl. 96, Figs 6–6c, 12, Pl. 102, Figs 2–2a (partim).—Borodin 1929: 36–42, Pl. 2 (integument and papillae).—Fauvel 1946: 401.—Støp-Bowitz 1948a: 33–37, Fig. 9.— Støp-Bowitz 1948b: 39–41, map (syn.).— Støp-Bowitz 1948c: 66–67 (syn.).—Wesenberg-Lund 1950a: 35–36.— Wesenberg-Lund 1950b: 85.—Oug et al. 2011: 13, Figs a–c (reproduced from Støp-Bowitz 1948a).

Brada granulata.—Moore 1909b: 143 (non Malmgren, 1867).

Material examined. Northeastern Atlantic Ocean. Faroe Islands. One specimen (MNHN 186), R.V. Pourquoi- Pas, Sta. 2, Klaksvik (62°14'00" N, 06°35'00" W), 8–15 m, 30 Jul. 1929 (most chaetae broken, papillae variously eroded; 23 mm long, 3.5 mm wide, cephalic cage 0.75 mm long, 23 chaetigers; gonopodial lobes in chaetiger 5, one blunt, the other mucronate). Barents Sea. Three specimens (MNHN 186 a), Swedish Expedition 1875–76, R.V. Yenissei, no further data (larger used for description; others 13–20 mm long, 3–4 mm wide, cephalic cage 1.5–2.0 mm long, 21–23 chaetigers; gonopodial lobes in chaetiger 5, pale, digitate). France. One specimen (MNHN 457), Tatihou (49º35'20" N, 01º14'36" W), P. Fauvel, coll. (14 mm long, 2.5 mm wide, cephalic cage 2 mm long, 21 chaetigers; gonopodial lobes in chaetiger 5, digitate, pale).

Description. Larger specimen (MNHN 186a) pale-brown, smaller ones paler; body wider anteriorly and medially, tapered posteriorly, posterior end regenerating (Fig. 45A), 20 mm long, 4 mm wide, cephalic cage 2.0 mm long, 21 chaetigers. Papillae long, basally covered with fine sand grains, medially with finer particles, easily removed, papillae tips long, free from sediment. Dorsal papillae larger, arranged in 4–5 transverse series (Fig. 45B); ventral papillae smaller (Fig. 45C).

Anterior end not exposed, observed after dissection. Cephalic tube short, margin smooth. Prostomium low, rounded, eyes not seen. Palps pale, thick, left one large, right one in regeneration, larger palp smaller than longest branchiae; palp keels low, rounded. Caruncle separating branchiae, with median keel and two lateral ridges, keel larger, more swollen. Lips distorted, dorsal lip reduced, right lateral lip expanded, left lateral and ventral lips reduced (Fig. 45D).

Branchiae cirriform, pale, sessile on branchial plate, separated into two lateral groups, filaments arranged in several rows, about 60 filaments per group. Nephridial lobes not seen.

Cephalic cage chaetae as long as ½ body width. Chaetigers 1–2 involved in cephalic cage; chaetae arranged in short lateral series, with 10 notochaetae and 8 neurochaetae per side.

Anterior margin of first chaetiger papillated, papillae about as long as adjacent ones. Chaetigers 1–3 of similar length. Chaetal transition from cephalic cage to body chaetae abrupt; slightly falcate aristate neurospines present from chaetiger 2. Gonopodial lobes pale, digitate, in chaetiger 5 (conical in smaller specimen, Fig. 45C).

Parapodia well developed, lateral. Median neuropodia ventrolateral. Notopodia and neuropodia close to each other. Notopodia with chaetal lobes rounded, short (Fig. 45E), with 2–3 inferior papillae, up to 1/5 as long as notochaetae; neuropodia larger rounded lobes, with 8–10 inferior long papillae, basally swollen.

Median notochaetae arranged in short transverse series, most notochaetae multiarticulate capillaries with articles short basally, medium-sized medially, slightly longer distally, 4–5 chaetae per bundle, as long as 1/3 body width. Neurochaetae multiarticulate capillaries in chaetiger 1; posterior chaetigers with slightly falcate, aristate neurospines, arranged in short transverse series in anterior chaetigers, in median and posterior chaetigers arranged in oblique or longitudinal series, 5–6 per bundle. Each neurospine with short rings basally, slightly shorter medially, distally hyaline, mucronate.

Posterior region in regeneration (Fig. 45F); pygidium conical, truncate, anus terminal, anal cirri absent.

Variation. Additional specimens 13–23 mm long, 2.5–4.0 mm wide, cephalic cage 1.5–2.0 mm long, 21–23 chaetigers.

Remarks. In the original description of Siphonostoma villosum, Rathke (1843:217) indicated 22 segments with an achaetous segment, thus 21 chaetigers, and his figure (Plate 16, Figure 11) shows a specimen with 22 segments. However, McIntosh (1915:106), thought there were two different forms under the same name; the northern form with fewer chaetigers (about 25), whereas the southern one had numerous chaetigers (up to 45). This observation, however, is not confirmed by the above specimens: the French specimen has 21 chaetigers whereas the Barents Sea specimens similarly have 21–23 chaetigers. Thus, the wide range of variation stated by McIntosh (1915) and Fauvel (1927:122), in their descriptions of B. villosa, encompassing 12–35 chaetigers, may mask some potentially different species under the same name: these alleged northern and southern forms, possess different body shapes, number of chaetigers and relative development of dorsal papillae. Type material of B. villosa has been lost, but the description herein includes specimens collected from the Faroe Islands, a similar latitude as the type locality (Molde, Norway, 62°45'23" N, 07°14'19" E). A species which may agree with McIntosh’s “southern form” is described herein as B. harrisae n. sp. with specimens from Norway and Sweden.

As stated in the key above, there are several species possessing about 20 chaetigers and whose dorsal body papillae have adhering sand particles. However, B. villosa (Rathke, 1843) n. comb., separates from them because it has very small notopodial papillae, being about 1/5–1/10 as long as notochaetae, whereas notopodial papillae in other species are about 1/2–2/3 as long as notochaetae.

There are many records for B. villosa from several localities all over the world, especially from cold or deep waters. In so far as there are no clear details about their morphological features, they must be regarded as questionable records.

Distribution. From the European-Russian Arctic region, throughout Scandinavia, and cold temperate Northern Atlantic Ocean.