Polycirrus latidens Eliason, 1962

Fig. 33a–e

Polycirrus latidens Eliason, 1962: 286–287, fig. 23.

Type locality. Skagerrak, Atlantic Ocean.

Material examined. HOLOTYPE: UUZM 196 a. Atlantic Ocean, Skagerrak, Uppsala Expedition coll. 5.vii.1933, St.22, Bergskrapa, 57˚59′ N, 8˚13.5′ E, 531 m, coll 5.vii.1933. PARATYPE: UUZM 196 B, Atlantic Ocean, Uppsala Expedition 1933, St.6. 58˚18.8ʹ N 9˚57’ E, coll 27.vi.1933.

Description. Type specimens well preserved with body wall intact and chaetae mainly intact, pale cream in colour. Holotype 17 mm long and 1.5 mm wide excluding buccal tentacles, incomplete with 20 segments. Paratype consists of three posterior fragments: 10 mm long and 1.2 mm wide for 15 segments, 4 mm long and 1.2 mm wide for 6 segments, and about 20 mm long (strongly coiled) and 1.2 mm wide for about 20 segments. The following description is based upon the holotype other than where stated. Sex female.

Dorsum anteriorly tessellated. Venter anteriorly with mid-ventral groove and discrete ventro-lateral pads; anterior pads with transverse grooves and tessellations extending from segment 5 to 9. Mid-ventral groove from segment 4 (Fig. 33a).

Buccal tentacles of one type, few remaining, cylindrical, uniformly thin and weakly grooved, some shorter than others; arising dorsally on prostomial ridge. Prostomial ridge distinctly curved, not extending laterally. Upper lip triangular, comprising medial lobe only, margin thickened and overturned; oral surface glandular, ciliated, with grooves leading to mouth. Inner lower lip subtriangular, hidden by upper lip, ridged; outer region flat, shield-like, oblong, wider than long, ridged and grooved, extending posteriorly to segment 4. Achaetous segments visible dorsally but obscured by expanded outer lower lip ventrally (Fig. 33a).

Notochaetigerous segments 12, extending to segment 14. Notopodia more-or-less rectangular but rounded distally, prechaetal lobe low, postchaetal lobe digitiform, longer than prechaetal (Fig. 33b). Notochaetae within a chaetiger consisting of one type (chaetigers 5, 14 examined), gradually elongating from dorsal to ventral, hirsute, uniformly tapered, posteriorly same form as those anteriorly (Fig. 33c). Neurochaetae beginning on segment 14. Neuropodial tori erect pinnules. Uncini with short neck and straight to convex base (Type 1), 3–5 teeth above main fang arranged in single vertical series (MF:1:1:1 to MF:1:1:1:1:1) subrostral process present as low angular protuberance (Fig. 33d,e).

Nephridial papillae present, cylindrical. Pre-gular membrane nephridial papillae present on segment 4 only. Post-gular membrane nephridial papillae present, extending from segment 5 to 8; situated at ventral base of notopodia (Fig. 33a).