Ophelina manana sp. nov.

Figures 13 (A–C) and 14 (A–E)

Material examined. Holotype: Mamala Bay, Oahu, Hawaii, Sta. D 3, 21°15'08.61" N, 157°54'29.75" W, Aug. 2000, in volcanic sediments and foraminiferan deposits, 400–500 m (BPBM-R3893). Paratype: same locality, collector and date as holotype (1 spm, BPBM-R3894).

Diagnosis. Branchiae absent. Anal tube short with two proximal transversal markings and ending on a conical segment; segment preceding anal cone with a dorsal pair of triangular protuberances; three elongate basal anal cirri, inserted from external body wall; cirri all of same length; at least four pairs of minute digitiform marginal papillae.

Description. Two complete specimens, holotype 4 mm long, 3 mm wide for 26 chaetigers and paratype 3 mm long, 0.3 mm wide for 26 chaetigers. Body slender, widest on mid-body and tapering towards posterior end (Fig. 13A). Preserved specimens pale yellow lacking distinct pigmentation. Prostomium conical, elongate and tapering to elongate terminal and clavate palpode (Figs 13A; 14B). Nuchal organs oval, postero-lateral (Figs 13A; 14B). Eyes absent. Pharynx partly everted in one specimen, tubular and oral tentacles not observed. Branchiae absent throughout.

Parapodia biramous, chaetae emerging from discrete parapodial lobes anteriorly and lobes becoming slightly more elongate on posterior end of body. Simple capillary throughout, 4–6 capillaries per fascicle anteriorly reducing to 2–4 posteriorly. Dorsal and ventral parapodial lobes absent (Fig. 14 C, D).

Anal tube short, as long as two last segments with two proximal transversal markings and ending on a conical segment (Figs 13B, C; 14E). Segment preceding anal cone with a dorsal pair of triangular protuberance (Figs 13B; 14E). Three elongate basal anal cirri present, inserted from external body wall; cirri all of same length; at least four pairs of minuscule digitiform marginal papillae (Figs 13B, C; 14E).

Remarks. Ophelina manana sp. nov. is unique in the genus by the absence of branchiae and structures of the last body segment and anal cone. The presence of a pair of dorsal triangular protuberances has never been reported in the genus. These structures are placed dorsally prior to the anal cone and presumably associated to the pygidium. The presence of three elongate basal cirri, and at least four pairs of marginal papillae also differ these specimens from its congeners. This species differs from its congeneric O. abranchiata, which also lack branchiae, on the structures of the anal cone, the latter having a long anal cone with a long, crenulated unpaired anal cirrus.

Etymology. The epithet of this species refers to the Hawaiian term Manana meaning “to protrude, as ears; to distend, as nostrils while breathing hard; swelling, as with disease” (Pukui & Elbert 1986). The species name was chosen in reference to the pair of dorsal triangular protuberances present on the posterior end prior to the pygidium resembling protruding ears.

Distribution. Only known from Mamala Bay, Oahu, Hawaii, 400–500 m in volcanic sediments and foraminiferan deposits.