Ophelina kohni, Magalhães & Rizzo & Bailey-Brock, 2019

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 : 228-231

Ophelina kohni sp. nov.

Figures 11 (A–E) and 12 (A–E)

Material examined. Holotype: Mariana Islands, Guam, Tanguisson Beach , outer reef flat and bench near Tanguisson Power Plant, 13°32'37.42" N, 144°48'27.95" E, January/18/1975, shallow subtidal, coll. A.J. Kohn ( BPBM-R3891 ) . Paratypes: same locality, collector and date as holotype (2 spms, BPBM-R3892 ). Additional material examined : same locality, collector and date as type material (2 spms on SEM stub). Comparative material examined. Ophelina grandis ( Pillai, 1961) Holotype, BMNH 1960.3 .13.17, Tambalagam Bay , Ceylon, T.G. Pillai .

Diagnosis. Branchiae present from chaetigers 2–3 and only absent on last three chaetigers. Anal tube funnelshaped, laterally compressed with 11–15 transversal markings; fin-shaped dorsally; unpaired ventral anal cirri absent; up to 4 pairs of slender and digitiform to elongate marginal papillae; paired basal papillae not distinct from marginal papillae.

Description. Holotype 9.5 mm long, 0.6 mm wide for 29 chaetigers. Paratypes 8–10 mm long, 0.4–0.5 mm wide for 28–30 chaetigers. Body slender tapering towards very posterior end ( Fig. 12A ). Preserved specimens pale yellow lacking distinct pigmentation. Prostomium conical, elongate and tapering to terminal palpode, clavate ( Figs 11A, B ; 12B ). Nuchal organs oval, postero-lateral ( Figs 11A, B ; 12B ). Eyes not observed in any specimen. Pharynx not observed. Branchiae from chaetiger 2–3 and only absent on last three chaetigers; branchiae short and similar in shape and length throughout, not meeting mid-dorsally ( Figs 11C ; 12C ).

Parapodia biramous, chaetae emerging from rounded postchaetal lobe anteriorly and lobes becoming digitate and longer posteriorly ( Figs 11C ; 12C, D ). Elongate ventral cirrus present ( Figs 11C ; 12C ). Simple and thin capillary chaetae present in two bundles anteriorly; 3–4 notopodial capillaries and 1–2 neuropodial capillaries, notopodial capillaries twice longer than neuropodial ones. Last five chaetigers with thick and long capillaries ( Figs 11D, E ; 12A, E ); 2–5 neuropodial capillaries and 3–6 notopodial capillaries; chaetae of last chaetiger surpassing anal tube ( Figs 11D, E ; 12A, E ).

Anal tube funnel-shaped, laterally compressed, as long as four last segments with 11–15 transversal markings ( Figs 11D ). Dorsal region extremely laterally compressed, fin-shaped dorsally; compressed dorsal region may extend for 2–3 posterior chaetigers ( Fig. 11D, E ). Unpaired ventral anal cirri absent in all specimens and paired basal papillae not distinct from marginal papillae; up to 4 pairs of slender and digitiform to elongate marginal papillae ( Figs 11D, E ; 12E ).

Remarks. The new species is distinct from all Ophelina species by a combination of characters such as: presence of branchiae throughout, shape of anal tube that is laterally compressed, shape of basal anal cirri, shape and number of marginal anal papillae, absence of dorsal lobe/cirri, presence and length of ventral lobe, absence of unpaired anal cirrus, and by the length of the chaetae of posterior end segments.

Ophelina species with laterally compressed anal tubes include O. cyprophilia Neave & Glasby, 2013 , O. fauveli (Caullery, 1944) , O. profunda (Caullery, 1944) , and O. tesselata Neave & Glasby, 2013 . Unpaired anal cirrus is present in O. cyprophilia , O. fauveli , O. profunda , and O. tesselata whereas is absent in O. kohni sp. nov. Ophelina tesselata has a club-shaped anal funnel with a ventral incision and about 40 marginal cirri. The anal cone in O. cyprophilia is similar in shape to the new species from Guam but differs by the presence of numerous (48) marginal cirri. The holotype of O. grandis Pillai, 1961 also shows a laterally compressed anal tube having a crenulate unpaired ventral cirrus, about 20 pairs of marginal papillae, elongate basally and becoming shorter towards the dorsal region of the anal tube.

Etymology. This species is named after Dr. Alan Kohn who donated the type specimens collected in Guam as part of his studies with Conus snails. Dr. Kohn has been very supportive of polychaete studies in the western Pacific and a kind and generous host when the author (J.H.B-B.) was a visiting faculty in his laboratory at the University of Washington.

Distribution. Only found in the type locality Tanguisson Beach, Guam, Mariana Islands.

Figures

FIGURE 11. Line drawings of Ophelina kohni sp. nov. from Guam, Mariana Islands: A, anterior end in lateral view; B, anterior end in dorsal view; C, parapodium from a posterior end segment; D and E, posterior end in lateral view with anal cone.

FIGURE 12. SEM of Ophelina kohni sp. nov. from Guam, Mariana Islands: A, complete specimen in lateral view; B, anterior end, dorso-lateral view; C, parapodium of mid-body; D, detail of prechaetal lobe; E, pygidium and posterior end segments in lateral view.