Bradabyssa ochotensis (Annenkova-Chlopina, 1922) Salazar-Vallejo, 2017

Salazar-Vallejo, Sergio I., 2017, Revision of Brada Stimpson, 1853, and Bradabyssa Hartman, 1967 (Annelida, Flabelligeridae), Zootaxa 4343 (1), pp. 1-98 : 54-55

Bradabyssa ochotensis (Annenkova-Chlopina, 1922) n. comb.

Figure 27

Brada ochotensis Annenkova-Chlopina 1922: 39 .—Uschakov 1955: 310(1965: 287), Fig. 115J.—Levenstein 1966: 45.—Jirkov & Filippova 2001: 354.

Type material. Holotype ( ZIRAS 26654 ), Sakhalin Bay, Okhost Sea, R.V. Liuetenant Dydymov, Sta. 400 (53°32' N, 141°15' E), 24 m, sand, 14(27) Aug. 1913, V.K. Soldatov, coll.

Additional material. One specimen (ZIRAS 26655), Bering Sea, R.V. Plastun, Sta. 3 (63°11' N, 172°35' E), 66 m, 12 Sep. 1931, coll. (85 mm long, 8 mm wide, cephalic cage 4 mm long, 31 chaetigers, gonopodial lobes in chaetiger 5, 5–6 series of dorsal papillae; dissected for introvert details).

Description. Holotype (ZIRAS 26654) complete ( Fig. 27A ), few parapodia previously removed, anteroventrally dissected. Body stiff, pale, slightly tapered posteriorly; 62 mm long, 12 mm wide, cephalic cage 5 mm long, 32 chaetigers. Tunic papillated, most larger papillae distally eroded, smaller ones covered by sediment. Papillae and integument finely covered by fine sand grains, not forming large sand tubercles. Papillae in two slightly different sizes and shapes; smaller ones digitate, larger ones globose, mucronate, about as large as neuropodial lobes, all arranged in 5–6 alternating series in median chaetigers ( Fig. 27B ).

Anterior end not exposed (observations made through original dissection, completed with another dissected specimen (ZIRAS 26655). Prostomium dark brown, rounded, low, eyes not seen. Palps short, heavily contracted, thick, with longitudinal furrow, and long tip (due to compression), shorter than branchiae; palp keels dark brown, rounded, elevated. Caruncle well developed, reaching posterior margin of branchial plate; median keel basally wide, elevated, lateral ridges dark, lower than keel. Lips grayish, thick; dorsal lip triangular, lateral lips thicker, ventral lip darker, slightly projecting.

Branchiae cirriform, sessile on branchial plate, separated into two lateral groups, filaments arranged in several rows, over 100 filaments per group. Nephridial lobes dark, present on lateral external basis of branchial group, each with double short maculate lobes.

Cephalic cage present, chaetae as long as 1/13 body length, or less than half body width. Chaetigers 1–2 involved in cephalic cage, all with very long notochaetae (chaetigers 3–4 with long notochaetae as well, but shorter than anteriormost two); chaetae arranged in short lateral series, chaetiger 1 with 12 notochaetae and 10 neurochaetae, chaetiger 2 with 10 notochaetae.

Anterior margin of first chaetiger rounded, papillae short, eroded. Chaetigers 1–3 of similar length. Chaetal transition from cephalic cage to body chaetae abrupt; aristate neurospines present from chaetiger 2. Gonopodial lobes in chaetiger 5, partially eroded ( Fig. 27C ).

Parapodia well developed, lateral ( Fig. 27D ). Median neuropodia ventrolateral. Notopodia and neuropodia close to each other. Notopodia with chaetal lobe rounded, with 3 inferior large, mucronate papillae, about 1/5 as long as notochaetae; neuropodia with larger rounded lobe, with 8–9 inferior papillae, decreasing in size ventrally, separated in two groups (anterior and posterior), leaving central area bare or with one filiform papillae; notopodial lobes rounded, short.

Median notochaetae arranged in short oblique series, all notochaetae multiarticulate capillaries with articles short basally, medium-sized medially, long distally ( Fig. 27E ), 5–6 chaetae per bundle, as long as 1/3 body width. Neurochaetae multiarticulate capillaries in chaetiger 1; posterior chaetigers with aristate neurospines, arranged in Jshaped patterns, 6–7 per bundle. Each neurospine with short rings basally, becoming slightly shorter medially, distally hyaline with long mucro ( Fig. 27F ).

Posterior end rounded, pygidium with anus terminal, anal cirri absent.

Variation. An additional specimen was 85 mm long, 8 mm wide, cephalic cage 4 mm long, 31 chaetigers. Remarks. Bradabyssa ochotensis (Annenkova-Chlopina, 1922) n. comb. belongs to the group of species which possess large dorsal papillae; it resembles B. annenkovae (Buzhinskaja, 2001) n. comb. and B. grangieri n. sp. by having neurospines with short anchylose articles. As indicated in the key above, B. ochotensis differs from the two other species by having more chaetigers (31–32 vs 19–26), although it is more similar to B. annenkovae because both have pale gonopodial lobes. Also, B. ochotensis is larger with more transverse series of globular papillae (5–6), whereas papillae are thinner and in fewer rows per segment (2–4) in B. annenkovae .

After examination of the type specimen, I noted a few discrepancies from the original description by Annenkova-Chlopina (1922:39): the specimen width is 12 mm by chaetiger 10 and it does not reach the 20 mm originally indicated; there are 32 (not 31) chaetigers, although the last one is very reduced and carrying minute notochaetae, as usual in the genus, which would explain it being overlooked; and the larger dorsal papillae are globose, not triangular, arranged in three transverse series in median chaetigers. Uschakov (1955:310(1965:287), Fig. 115J) stated that the body had 29–31 chaetigers. Jirkov & Filippova (2001:354) recorded it from the Arctic with an average of 24 chaetigers, and indicated that this species lacks any sediment cover. Although there are subtle differences in the size of verrucae and of ecological conditions in their type localities, notochaetal articles sizepatterns are similar such that a size-dependent variation analysis must be made before concluding B. ochotensis and B. annenkovae are conspecific.

Distribution. Okhotsk and Bering Seas, in shallow water.

Figures

FIGURE 27. Bradabyssa ochotensis (Annenkova-Chlopina, 1922) n. comb., holotype (ZIRAS 26655). A. Dorsal view. B. Anterior end, dorsal view. C. Anterior end, ventral view. D. Chaetiger 8, right parapodium, E. Same, notochaetal basal, medial and distal regions. F. Chaetiger 9, right parapodium, neurochaeta. Scale bars: A: 3.4 mm, B: 2.4 mm, C: 2.1 mm, D: 0.4 mm, E: 50 µm, F: 150 µm.