Bradabyssa pluribranchiata (Moore, 1923) 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 : 81-83

Bradabyssa pluribranchiata (Moore, 1923) n. comb.

Figure 42

Stylarioides pluribranchiata Moore, 1923: 222 –223.

Brada pluribranchiata: Hartman 1969: 279 –280, 7 textfigs. (n. comb.).—Fauchald 1972: 216.—Loi 1980: 137–138.

Type material. Northeastern Pacific Ocean, California. Holotype ( USNM 17402 ), R.V. Albatross, Sta. 4450, 110 m, Monterrey Bay , 11 May 1904 . Paratype ( ANSP 3273 , originally regarded as cotype, also used for description), R.V. Albatross, Sta. 4412, off Bird Rock, Santa Catalina Island , 485–501 m, mud, gravel, rocks, 11 Apr. 1904 .

Additional material. Northeastern Pacific Ocean , California. Anterior fragment ( ANSP 3270 ) distorted by pressure, anterior end partially everted, R.V. Albatross, Sta. 4307, off Point Loma Lighthouse , 309–908 m (897 m in publication), mud and fine sand, 2 Mar. 1904 (15 mm long, 3 mm wide, cephalic cage 3 mm long, 15 chaetigers; gonopodial lobes in chaetiger 5; anterior end dissected and two parapodia removed for chaetae). Two anterior fragments ( ANSP 3271 ), R.V. Albatross, Sta. 4326, off Point La Jolla , 445–512 m, mud, 8 Mar. 1904 (10 mm long, 1.8–2.0 mm wide, cephalic cage 3 mm long, 15–16 chaetigers; nephridial lobes in chaetiger 5). One specimen ( ANSP 3272 ), broken into two pieces, R.V. Albatross, Sta. 4369, off Point Loma Lighthouse , 476–520 m, mud, sand and rocks, 16 Mar. 1904 (16.5 mm long, 2 mm wide, cephalic cage 2.5 mm long, 29 chaetigers; nephridial lobes in chaetiger 5).

Description. Holotype (USNM 17402) damaged; body subcylindrical, anteriorly blunt, tapered posteriorly ( Fig. 42A ), breaking into two pieces (several parapodia previously removed); 25.5 mm long, 2.5 mm wide, cephalic cage 4 mm long, 37 chaetigers. Paratype (ANSP 3273) mature female, complete, body rectangular, pale, anteriorly blunt, tapered posteriorly, slightly bent ventrally (a lateral section of body wall previously removed), 26 mm long, 2 mm wide, cephalic cage 2.5 mm long, 33 chaetigers.

Papillae completely covered by fine sand particles ( Fig. 42B ). Papillae size alternating, long or short, with globular base and long mucro, larger dorsally, more or less arranged in 5–6 transverse series, with 2–3 series with larger papillae; intersegmental areas bare, smaller papillae present in inter-parapodial spaces.

Anterior end exposed, eroded in paratype (dissected in ANSP 3270). Cephalic tube short, margin smooth. Prostomium rounded lobe, eyes colorless. Palps thick, slightly longer than branchiae, pale, slightly darker along furrow (paratype with one palp left, ventral side furrowed, with medially swollen longitudinal lobe and lateral sides darkened); palp keels rounded, projected ( Fig. 42D ). Caruncle extended posteriorly separating branchiae into two lateral groups, with medially swollen keel and two lateral ridges. 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 radial series, up to 70 filaments per group (most branchiae missing in paratype). Nephridial lobes not seen (perhaps emerge from branchial central area).

Cephalic cage chaetae as long as 1/10 body length, or slightly longer than body width. 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 5 notochaetae and 4 neurochaetae per side, chaetiger 2 with 4 notochaetae, and 3 aristate neurospines.

Anterior margin of first chaetiger rounded, with very few short papillae, appearing smooth. Chaetigers 1–3 slightly decreasing in length posteriorly. Chaetal transition from cephalic cage to body chaetae abrupt; aristate neurospines present from chaetiger 2. Gonopodial lobes in chaetiger 5 in holotype ( Fig. 42C ) and paratype.

Parapodia well developed, lateral. Median neuropodia ventrolateral. Notopodia and neuropodia close to each other. Notopodia with chaetal lobe rounded, with 2 inferior long papillae ( Fig. 42E ); neuropodia with larger rounded lobe, with inferior semicircle of 7–8 long papillae; 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. 42F ), 4–5 chaetae per bundle, as long as half 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, slightly falcate mucro ( Fig. 42G ).

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

Oocytes in paratype about 100 µm in diameter.

Variation. Additional specimens 10.0– 16.5 mm long, 1.8–3.0 mm wide, cephalic cage 2.5–3.0 mm long, 15–29 chaetigers.

Remarks. Bradabyssa pluribranchiata (Moore, 1923) n. comb. resembles other species with 28–33 chaetigers and pale gonopodial papillae, such as B. setosa (Verrill, 1873) n. comb., and an undescribed species from Brazil. However, B. pluribranchiata is distinguished from these two species by possessing fine sediment particles adhering on dorsal papillae, whereas the other two ones have large sand particles.

Moore (1923:222) described the body as having “… relatively coarse, rough papillae, arranged more or less regularly in four transverse series on each segment. They are of fairly uniform size …” It seems that he overlooked the smaller alternating papillae due to the poor condition of his specimens despite having recognized the poor preservation state of specimens in the previously published first part of the “Albatross” reports (Moore 1909b:321), and wrote: “Among the material gathered is a rich but rather indifferently preserved collection of Polychaeta …”.

In his original description, Moore (1923: 223) indicated that the type (= holotype) was collected from Albatross station 4430, off Santa Cruz Island, rendering his cotype, from Albatross Sta. 4412, as the paratype. This has been already pointed out by Loi (1980:138); however, there is a serious disagreement concerning the holotype locality because Loi indicated it belongs to the USNM, and that it comes from the R.V. Albatross station 4450, off Monterey, California. This discrepancy in the station data indicates that labels might have been confused, and therefore the paratype has been also used in the redescription.

Distribution. California, U.S.A. in sediments at 110–908 m water depth.

Figures

FIGURE 42. Bradabyssa pluribranchiata (Moore, 1923) n. comb., holotype (USNM 17402): A. Oblique dorsal view. B. Anterior region, right lateral view (first chaetiger previously removed). C. Anterior region, ventral view (arrows point to gonopodial lobes). D. Non-type specimen (ANSP 3270), head, frontal view, after methyl-green staining and removal of branchial filaments and palps (Ca: caruncle, Br: branchial scars, PK: palp keel, PS: palp scar). E. Same, chaetiger 15, right parapodium, posterior view. F. Same, basal, medial and distal notochaetal regions. G. Same, basal, medial and distal neurochaetal regions. Scale bars. A: 1.7 mm, B: 0.5 mm, C: 0.8 mm, D: 0.3 mm, E: 140 µm, F: 80 µm, G: 90 µm.