Bradabyssa irenaia ( Chamberlin, 1919 ) 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 : 48-50

Bradabyssa irenaia ( Chamberlin, 1919) n. comb.

Figure 24

Brada irenaia Chamberlin, 1919: 400 –401, Pl. 68, Figs 7–9 , Pl. 69, Figs 1–3 .

Type material. Eastern Tropical Pacific. Holotype of Brada irenaia ( USNM 19340), R.V. Albatross Tropical Pacific Expedition, off southern Panama, Sta. 3382 (06°21' N, 80°41' W), 3281 m, green mud, 7 Mar. 1891.

Description. Holotype (USNM 19340) damaged, broken in two portions, partly dehydrated, body dark, slightly fusiform ( Fig. 24A ); 43(27+16) mm long, 5.5 mm wide, cephalic cage chaetae broken, 41 (23+18) chaetigers. Tunic papillated, dorsal papillae larger, globular, in 4–5 alternating series per chaetiger ( Fig. 24B ), ventral papillae smaller, arranged in 8–9 alternating series per chaetiger, each with smaller or larger papillae; without thick tunic, sediment grains adherent to papillae, not forming large tubercles.

Anterior end exposed, mostly eroded ( Fig. 24C, D ). Prostomium eroded. Caruncle eroded posteriorly, separating branchial plate, median keel and lateral ridges eroded, probably converging posteriorly. Palps large, one missing, remaining one with tip partially eroded, not corrugated; palp keels low, rounded.

Branchiae missing, branchial scars arranged into two lateral groups, each with filaments in radiating series, about 110 scars per group. Individual lips not discernable, smashed and eroded (ventral pharyngeal bulb slightly exposed). Nephridial lobe scars in lower half of branchial plate, each as rounded darker lobes.

Cephalic cage probably present (notochaetae in chaetiger 4 very long), chaetae as long as 1/8 body length, or slightly shorter than body width. Chaetal lobes of chaetiger 1 with chaetal bases arranged in short lateral series, chaetal number unknown.

Anterior dorsal margin of first chaetiger rounded, papillated. Anterior chaetigers with anteroventral filaments, probably epizoans. Chaetigers 1–3 of similar length. Chaetal transition from cephalic cage to body chaetae abrupt; aristate neurospines present from chaetiger 2 (most broken, bases remain). Gonopodial lobes dark, rounded, short lobes in chaetiger 5 ( Fig. 24D ).

Parapodia well developed, lateral. Notopodia and neuropodia close to each other. Median neuropodia ventrolateral. Notopodia short low rounded lobes, with 3–4 long papillae. Neuropodia larger rounded lobe, 8–10 marginal papillae (mostly eroded), each with globular base.

Median notochaetae arranged in short transverse series; all notochaetae multiarticulate capillaries, articles short basally and medially, distally long ( Fig. 24E ); 6–8 per bundle, as long as 1/3 body width. Chaetiger 1 neurochaetae missing, aristate neurospines from chaetiger 2, most eroded, few smaller ones with tips aristate, tapered, slightly curved ( Fig. 24F ); 7–8 per bundle, arranged in È-shaped patterns; each neurospine with rings short, decreasing in length medially and distally, penetrating aristal basis, tip hyaline, recurved.

Posterior end tapered into rounded lobe ( Fig. 24G ); pygidium with anus dorso-terminal, round opening; anal cirri absent.

Remarks. Bradabyssa irenaia ( Chamberlin, 1919) n. comb. differs from B. verrucosa ( Chamberlin, 1919) n. comb., both coming from abyssal sediments in the Eastern Pacific, by the relative size of the larger dorsal papillae. In B. irenaia there is no large epi-notopodial papillae, whereas there is one in B. verrucosa , another difference being that there are 8–9 ventral transverse series of papillae in B. irenaia whereas there are only 2–3 ventral transverse series in the latter.

Chamberlin (1919:401) regarded B. irenaia as closely resembling B. villosa ( Rathke, 1843) , and separated them by the relative chaetal size. The type and number of papillae provide more striking differences; most papillae in B. villosa are of similar size and slightly swollen basally, whereas in B. irenaia dorsal papillae are of two markedly different sizes. Thus, B. irenaia resembles those species that possess dorsal papillae arranged in alternating size and position, but it differs from these by the number of transverse series of papillae, as stated in the key above.

However, as indicated above, Bradabyssa irenaia ( Chamberlin, 1919) n. comb. also resembles B. abyssalis ( Fauchald, 1972) n. comb. by having about 5 series of dorsal tubercles. They differ because in B. irenaia neurochaetae are tapered and integument is dark, whereas in B. abyssalis neurochaetae are medially cleft and integument is pale. Furthermore, in B. irenaia notochaetae have short rings basally and medially, whereas in B. abyssalis they are present only basally.

Distribution. Pacific Ocean, off Panama, in sediments deeper than 3200 m water depth.

Figures

FIGURE 1. Morphological features of Brada Stimpson, 1853, and Bradabyssa Hartman, 1967. A. Brada granulosa Hansen, 1880, lateral view. B. neurochaeta. C. Bradabyssa (olim Trophonia) rugosa (Hansen, 1880) n. comb., lateral view. D. Median parapodium. E. Notochaeta. F. Neurochaeta (modif. after Hansen 1880).

FIGURE 2. Brada granosa Stimpson, 1853. A. Neotype (USNM 1422407), lateral view, anterior end to the right (inset: small paratype, lower right in Fig. 3 A). B. Same, anterior end, ventral view (arrows point to gonopodial lobes). C. Non-type specimen (USNM 22851), head dissected, branchiae and palps removed (Br: branchial scar, PS: palp scar). Scale bars: A: 1.7 mm, B: 1.3 mm, C: 0.4 mm.

FIGURE 3. Brada granosa Stimpson, 1853. A. Juveniles (USNM 453). B. Non-type specimens (USNM 22851), chaetiger 2, right parapodium, anterior view. C. Same, notochaetal basal, medial and distal regions. D. Same, neurochaetal tips. E. Chaetiger 17, right parapodium, anterior view. F. Same, neurochaetal tips. Scale bars: A: 0.8 mm, B, E: 0.3 mm, C: 80 µm, D, F: 20 µm.

FIGURE 7. Brada kudenovi n. sp. A. Holotype (CAS 157753), oblique ventral view. B. Same, anterior end (arrow points gonopodial papilla). C. Paratype (CAS 158549), head, frontal view, greenish after methyl-green staining (palps and branchiae removed; Br: branchial scar, PS: palp scar). D. Holotype (CAS 157753), anterior parapodia, chaetigers 4 – 7 (anterior end to the right), oblique ventral view. E. Paratype (CAS 157752), chaetiger 11, right parapodium, anterior view. F. Same, basal, medial and distal notochaetal regions. G. Same, neurochaetae (inset: chaetal tips). Scale bars: A: 2.7 mm, B: 1 mm, C: 0.2 mm, D: 0.5 mm, E: 0.3 mm, F: 50 µm, G: 30 µm.

FIGURE 8. Bradabyssa indica n. sp., holotype (MNHN IA-Type 1797). A. Dorsal view. B. Ventral view. C. Anterior end, chaetigers 1 – 3, dorsal view. D. Chaetiger 1, basal notochaetal region. E. Chaetigers 2 – 3, left parapodial neurochaetae, ventral view. F. Chaetiger 4, left parapodial neurochaetae, ventral view. Scale bars: A: 0.4 mm, B: 0.3 mm, C: 0.1 mm, D – F: 40 µm.

FIGURE 9. Bradabyssa mexicana n. sp., holotype (LACM 7228). A. Dorsal view. B. Anterior end, dorsal view, bluish after methyl-green staining. C. Ventral view. D. Head, frontal view, cut open to show branchial scars, palps and branchiae removed, greenish after methyl-green staining (Br: branchial scars, PS: palp scar). E. Chaetiger 10, neurochaetae (inset: neurochaetal tips). Scale bars: A: 0.8 mm, B: 0.3 mm, C: 1.1 mm, D: 0.2 mm, E: 60 µm.

FIGURE 24. Bradabyssa irenaia (Chamberlin, 1919) n. comb., holotype (USNM 19340). A. Dorsal view. B. Anterior end, dorsal view. C. Anterior end, right lateral view, head exposed, eroded (Br: branchial scars, Pa: palp, VPO: ventral pharyngeal organ). D. Anterior end, ventral view (arrows point to gonopodial lobes; VPO: ventral pharyngeal organ). E. Chaetiger 15, right parapodium, basal, medial and distal notochaetal regions. F. Chaetiger 9, right parapodium, tips of smaller neurospines and medial portion of a larger, broken neurospine (inset: neurospine tip). G. Posterior end, dorsal view. Scale bars: A: 3.2 mm, B: 1.3 mm, C: 0.5 mm, D: 0.8 mm, E: 20 µm, F: 100 µm, G: 1 mm.