Bradabyssa tenebricosa Salazar-Vallejo 2017, n. comb.

Bradabyssa tenebricosa (Berkeley, 1966) n. comb., n. status

Figure 29

Flabelligera essenbergae tenebricosa Berkeley, 1966: 845 –846.

Brada sachalina?. —Banse & Hobson 1968: 40–41 (non Annenkova-Chlopina, 1922).

Brada sachalina.—Hobson 1976: 137–138.—Hobson & Banse 1981: 58, Fig. 11a (non Annenkova-Chlopina, 1922).

Type material. Northeastern Pacific Ocean. Holotype of Flabelligera essenbergae tenebricosa (BCPM 973.60.14N), Puget Sound, Washington, Sta. unnumb. (47°42'16" N, 122°26'24" W), 172–210 m, clay sand, 21 May 1963.

Additional material. Northeastern Pacific Ocean. One specimen (BCPM 27.3), Satellite Channel, center; no further data (11 mm long, 2 mm wide, cephalic cage 2 mm long, 27 chaetigers; gonopodial papillae not seen; 3 transverse series of papillae in chaetiger 10). Two specimens (BCPM 44.61), smaller one broken in two pieces, Burrard Inlet (49°18.5' N, 123°12.8' W), 43–71 m, 7 Dec. 1965 (7.0– 8.5 mm long, 2 mm wide, cephalic cage 1.5 mm long, 24–25 chaetigers; gonopodial papillae not seen; 3 transverse series of papillae in chaetiger 10). Two specimens (BCPM 46.17), Jervis Inlet (49°48.4' N, 124°03.0' W), 594–680 m, 9 Dec. 1975 (smaller complete, broken in two, 11+ 5 mm long, 2.3 mm wide, cephalic cage 1.0 mm long, 14+11 chaetigers; gonopodial papillae in chaetiger 5; 4 transverse series of papillae in chaetiger 10). Nineteen complete specimens and several fragments (BCPM 50.27), Strait of Georgia, R.V. Southern, 259 m, silty clay, 25 May 1966 (9–19 mm long, 2–3 mm wide, cephalic cage 1.0–3.0 mm long, 23–26 chaetigers; gonopodial papillae in chaetiger 5; 3–4 transverse series of papillae in chaetiger 10; even smallest specimens with dorsal papillae distinct). One specimen (BCPM 172.2), Fulford Harbor (48°45'41" N, 123°26'35" W), 24 m, 10 Feb. 1965, D. Ellis, coll. (13 mm long, 2.5 mm wide, cephalic cage 2.5 mm long, 27 chaetigers; gonopodial papillae in chaetiger 5; 3 transverse series of papillae in chaetiger 10). One specimen (BCPM 974.17.4), Strait of Georgia (49°21.5' N, 123°43.8' W), 161–168 m, mixed bottom with rocks, 29 Jan. 1974, P. Lambert, coll. (14 mm long, 2.5 mm wide, cephalic cage 2 mm long, 26 chaetigers; gonopodial papillae in chaetiger 5; 3 transverse series of papillae in chaetiger 10). One specimen (BCPM 975.19.1), Berkeley Collection, damaged, Belize Inlet (51°07.8' N, 127°33.3' W), 190 m, mud, Aug. 1968 (68–18) (33 mm long, 4.5 mm wide, cephalic cage 4 mm long (7–8 notochaetae/ 5–6 neurochaetae), 27 chaetigers; gonopodial papillae in chaetiger 5; 4 transverse series of papillae in chaetiger 10). Eleven specimens (BCPM 975.20.1), three anterior fragments and 8 juveniles, Berkeley Collection, off Barkley Sound (48°43.1' N, 125°22.2' W), 128 m, mud, Sep. 1968 (FRB 68-40) (smaller specimens 3.3–5.0 mm long, 0.7–1.0 mm wide, cephalic cage 0.3–0.6 mm long, 20–22 chaetigers; gonopodial papillae not seen; 2–3 transverse series of papillae in chaetiger 10). One specimen (BCPM 986.86.11), no further data (12.5 mm long, 2 mm wide, cephalic cage 2 mm long, 23 chaetigers; gonopodial papillae in chaetiger 5; 4 transverse series of papillae in chaetiger 10; head exposed, 36 branchial filaments per group). Two specimens (USNM 23265), Point Barrow, Alaska, washed ashore, 10 Aug. 1950, G.E. MacGinitie, coll. (40–48 mm long, 4–11 mm wide, cephalic cage 2–3 mm long, 24–27 chaetigers; gonopodial lobes black, digitate, in chaetiger 5). Two specimens (USNM 38168), off Puget Sound, Washington, Sta. 2 (47º42'16" N, 122º26'24" W), 196 m (172–216), 21 May 1967, K. Banse, coll. (9.5–15.5 mm long, 1.5–4.0 mm wide, cephalic cage 2.0– 3.5 mm long, 25 chaetigers; gonopodial lobes darker than surrounding tissues, in chaetiger 5). Three specimens (USNM 1422405), one complete, off Oregon, Bureau of Commercial Fisheries, SW Mouth Columbia River, R.V. Commando, anchor dredge, Sta. unnumb. (45°55.5' N, 124°42.5' W), 366 m, 23 May 1964, M.S. Alton, coll. (complete 35 mm long, 2.5 mm wide, cephalic cage chaetae missing, 24 chaetigers). An anterior fragment (CAS), Monterey Bay benthic study code: 70082305001-1 (mature female, 19 mm long, 2.3 mm wide, cephalic cage 2.5 mm long, 19 chaetigers; oocytes about 100 µm in diameter). Two complete specimens (LACM 2221), 4 km off Point Fermin Light, California (33°41'17" N, 118°20'17" W), 269 m, gray-green mud, 27 Feb. 1953 (9–11 mm long, 3 mm wide, cephalic cage 2.3–2.7 mm long, 25 chaetigers). Two complete specimens (LACM 2302), 2 km off Ship Rock Light, Santa Catalina Island, California (33°28'30" N, 118°28'05" W), 339 m, gray-green mud, 25 Apr. 1953 (smaller one with herpyllobiid copepod parasites).

Description. Holotype of Flabelligera essenbergae tenebricosa (BCPM 973.60.14N), complete, fusiform, regenerating posterior end, slightly damaged, most of tunic missing leaving pale body wall exposed (Fig. 29A); 12 mm long, 3 mm wide, cephalic cage 2.3 mm long, 22 chaetigers. Tunic papillated, thin, with fine sediment grains. Dorsal tubercles large, alternating, in two series with larger or medium sized ones, and two series with smaller papillae close to intersegmental regions, 3–4 series per segment in mid-body; ventral papillae decreasing in size posteriorly, in 3 alternating rows.

Anterior end not dissected (observed in BCPM 986.86.11). Cephalic tube short, margin smooth. Prostomium rounded lobe, eyes colorless. Palps contracted, thick, pale, slightly shorter than longest branchiae. Palp keels low, rounded. Caruncle extended posteriorly separating branchiae into two lateral groups, with median swollen keel and two lateral ridges (Fig. 29C). Dorsal lip reduced; lateral lips larger (damaged by dissection); ventral lip retracted.

Branchiae cirriform, sessile on branchial plate, separated into two lateral groups, filaments arranged in several parallel rows, about 50 filaments per group. Nephridial lobes not seen (single, minute conical projection on the inner margin of branchial plate in USNM 1422405).

Cephalic cage chaetae slightly shorter than body width in holotype. Chaetigers 1–2 involved in cephalic cage, chaetiger 1 displaced dorsally, chaetiger 2 with notochaetae shorter than chaetiger 1 but longer than following chaetigers; chaetae arranged in short lateral series, chaetiger 1 with 4–5 notochaetae and 3–4 neurochaetae per side, chaetiger 2 with 3–4 notochaetae, and aristate neurospines.

Anterior margin of first chaetiger with three large papillae. Chaetigers 1–3 enlarging posteriorly. Chaetal transition from cephalic cage to body chaetae abrupt; aristate neurospines present from chaetiger 2. Gonopodial lobes in chaetiger 5, pale, low ridges (Fig. 29B).

Parapodial well developed, lateral (Fig. 29D). Median neuropodia ventrolateral. Notopodia and neuropodia close to each other. Notopodia with chaetal lobe rounded, with 2 inferior long papillae present on bulbous lobe; neuropodia with larger rounded lobe, with inferior semi-circle of 5–6 long papillae, often separated into two sublateral rounded lobes (especially in larger specimens); notopodial lobes rounded, short.

Median notochaetae arranged in short transverse series, all notochaetae multiarticulate capillaries with articles short basally, medium-sized medially, longer distally (Fig. 29E), 4–5 chaetae per bundle, as long as 1/3 body width. Neurochaetae multiarticulate capillaries in chaetiger 1; posterior chaetigers with aristate neurospines, arranged in oblique series, 4–5 per bundle. Each neurospine with short rings basally, become shorter medially, distally hyaline with long mucro (Fig. 29D).

Posterior end in regeneration, tapered into rounded cone; pygidium with anus terminal, anal cirri absent (Fig. 29F).

Variation. Non-type specimens: juveniles (no gonopodial papillae) 3.3–8.5 mm long, 0.3–1.0 mm wide, cephalic cage 0.3–0.6 mm long, 20–22 chaetigers; adults: 9–48 mm long, 4–11 mm wide, cephalic cage 1–4 mm long, 23–27 chaetigers.

Remarks. Flabelligera essenbergae tenebricosa Berkeley, 1966, was regarded as a junior synonym of B. sachalina by Hobson (1976:137–138), and somehow intermediate between B. sachalina and B. ochotensis. The original description is very brief but Cyril Berkeley made an equivalent expression to the designation of holotype (ICZN, 1999, Art. 73.1.1): “The single specimen on which this subspecies is based …” At the same time, the original description was confusing because it was regarded as closely allied to F. essenbergae Hartman, 1961, but with differences in body color, relative papillae development, relative parapodial development, type of neurochaetae, and habitat. Furthermore, some features may have been wrongly copied from the original notes; thus, he stated that his specimen was 22 mm long (which is the chaetiger number), and that it had 45 segments. However, he also indicated that his specimen was obtained from deep water (183 m) which matches the collecting depth for the specimen (if there would be a confusion of the depth data, the only other specimen available in his possession was collected in 190 m (BCPM-975.19.1), but two years after the corresponding publication. All of these differences are regarded as unfortunate confusions, and after the evaluation of all specimens deposited in the same collection, the specimen regarded as the holotype is confirmed as such.

The basic features for the species are: body covered by large clear brown papillae, more closely packed towards body ends, body wall white, neurochaetae simple, almost straight to the colorless tips. Therefore, this is very far from any resemblance to F. essenbergae Hartman, 1961, which was revised elsewhere (Salazar-Vallejo 2007), and is now regarded as a junior synonym of F. papillosa (Essenberg, 1922).

Bradabyssa tenebricosa (Berkeley, 1966) n. comb., n. status, closely resembles B. verrucosa (Chamberlin, 1919). They differ in the relative development of chaetiger 2, being larger in the latter, and in the relative shape of the larger dorsal papillae, being globose in the former and slightly compressed in the latter.

Also, B. tenebricosa resembles B. sachalina (Annenkova-Chlopina, 1922) n. comb. but the latter species has poorly developed papillae forming a continuous dorsal sand cover on each segment; however, as stated above, the illustration emphasized the rounded papillae but they are depressed instead of being elevated, as is the case for B. tenebricosa. The change in rank must retain the original author because it was proposed as subspecies (ICZN 1999, Art. 50.3). In the original description by Berkeley, it was stated that the papillae could be detected, which implies that the papillae were not completely covered by a sediment crust, such that their shape is distinct. This feature would separate it from the true B. sachalina as well as by the number of chaetigers, which Hobson (1976:138) stated as 22–28 (mean 24), whereas B. sachalina possesses 21–22.

Distribution. Northeastern Pacific, Canada to Southern California, in 43–269 m water depth.