Ophelina cf. chaetifera ( Hartman, 1965 )

Magalhães, Wagner F., Rizzo, Alexandra E. & Bailey-Brock, Julie H., 2019, Opheliidae (Annelida: Polychaeta) from the western Pacific islands, including five new species, Zootaxa 4555 (2), pp. 209-235 : 226

Ophelina cf. chaetifera ( Hartman, 1965)

Figure 10 (A–C)

Ammotrypane chaetifera Hartman, 1965: 187 , pl. 43.

Ophelina chaetifera: Hartman & Fauchald 1971: 131 ; Barroso & Paiva 2013: 2 –3, fig. 2.

Material examined. Oahu, Hawaii: Mamala Bay, Jun/1995, Sta. 12.2.B, 21°13'50.21" N, 157°57'00.18" W, 481 m (1 spm, BPBM-R3889); Sta. 3.3.B, 21°14'30.18" N, 157°54'29.75" W, 491 m (2 spms); Sta. 6.1.B, 21°13'19.68" N, 157°57'05.70" W, 498 m (1 spm).

Diagnosis. Branchiae present from chaetigers 2–4, absent on mid-body and present again posteriorly for 3–4 chaetigers. Anal tube as long as four last segments with 8–9 transversal markings; 4–5 small and digitiform marginal papillae; unpaired ventral anal cirrus convoluted and thick, inserted ventrally from external body wall.

Description. Four complete specimens, ranging from 2.2–5 mm long, 0.2–0.3 mm wide, with 25–28 chaetigers. Body slender, widest on mid-body and tapering towards posterior end ( Fig. 10A ). Preserved specimens pale yellow lacking distinct pigmentation. Prostomium conical, elongate and tapering to terminal palpode, clavate ( Fig. 10A ). Nuchal organs oval, postero-lateral. Eyes not observed in any specimen. Pharynx everted in one specimen, globular and lacking tentacles ( Fig. 10A ). Branchiae present from chaetigers 2–4 (one specimen with branchiae from 2–6), absent on mid-body and present again posteriorly on 3–4 chaetigers, usually ending 3–4 chaetigers before anal tube; anterior branchiae shorter and slenderer than posterior ones; branchiae of posterior end increasing in length on posterior chaetigers but last branchia slightly shorter than preceding ones.

Parapodia biramous, chaetae emerging from discrete parapodial lobes anteriorly and lobes becoming slightly more elongate on last ten segments. Two types of chaetae present: simple capillary chaetae in two bundles anteriorly; 4–6 notopodial capillaries and 4–5 neuropodial capillaries, notopodial capillaries slightly longer than neuropodial ones. Simple capillaries replaced by thicker and somewhat spinulose modified capillaries on last 6–8 chaetigers; 3–4 modified capillaries per bundle, becoming progressively longer posteriorly and chaetae of last chaetiger surpassing anal cone.

Anal tube as long as four last segments with 8–9 transversal markings and longitudinally grooved ( Fig. 10B, C ). Unpaired ventral anal cirrus present, inserted ventrally from external body wall; cirrus half the length of anal tube, surpassing about ¼ tube’s length, convoluted and somewhat thick ( Fig. 10B, C ); 4–5 small and digitiform marginal papillae, difficult to observe.

Remarks. The Hawaiian material agrees with the original and subsequent descriptions of O. chaetifera ( Hartman 1965; Hartman & Fauchald 1971; Barroso & Paiva 2013). There are variations according to the number of branchial-bearing segments anteriorly but the value of this taxonomic character is poorly understood. Hartman (1965) described the holotype as having five pairs of branchiae (chaetigers 2–4 and in two segments of posterior end). Hartman & Fauchald (1971) described specimens also having five pairs in a different configuration (chaetigers 2 and 3 and three segments of posterior end). Barroso & Paiva (2013) described material from Brazil as having six pairs (chaetigers 2–4 and three segments of posterior end). One specimen from Hawaii presented seven pairs of branchiae (chaetigers 2–4 and four segments of posterior end) and for this reason it was decided to identify it as Ophelina cf. chaetifera .

Distribution. Originally described from off New England in 1,50 0–4,667 m and Guianas at 1,500 m ( Hartman 1965) and reported to Campos Basin in the South Atlantic, 1,039–1,650 m ( Barroso & Paiva 2013). This putative species is recorded for the first time to Hawaii for depths of 481– 498 m.

Figures

FIGURE 10. Line drawings of Ophelina species from Mamala Bay, Hawaii: A, a complete specimen of Ophelina cf. chaetifera in dorso-lateral view; B and C, posterior end of O. cf. chaetifera with anal funnel in lateral and ventral view, respectively; D, a complete specimen of Ophelina abranchiata in ventro-lateral view; E, posterior end with anal funnel of O. abranchiata in lateral view.