Hexelasma velutinum Hoek, 1913

Figures 2 I, 29, 30

Hexelasma velutinum Hoek, 1913: 246, pl. 26 figs 1–6. — Broch, 1931: 53. — Hiro, 1933: 70, pl. 3 fig. 2. — Utinomi, 1968: 30. — Newman & Ross, 1971:155. — Newman & Ross, 1976: 46. — Jones, 2000: 273, fig. 64, tabs 28–31. — Liu & Ren, 2007: 328, fig. 146.

Material examined. CEL-BB-102, 1 specimen, Stn. CP371 (24º28.521’N, 122º12.821’E, 26 Aug. 2006, depth: 582–613 m), BD 13.88 mm.

Diagnosis. Shell with 6 compartmental plates; carina, carinolateral and lateral plates with alae, radii absent; rostrum with radii and alae absent; parietes solid, longitudinal ribs on inner surface absent; basis membranous; intermediate segments of cirri IV–VI bearing 2 pairs of long setae.

Description. Shell white, conical or cylindrical, operculum large; shell surface with parallel growth lines, covered by membrane with fine, short setae (Fig. 2 I); 6 compartmental plates; carina, carinolateral and lateral plates with alae, radii absent; rostrum with radii and alae absent (Fig. 2 I); parietes solid, longitudinal ribs on inner surface absent; basis membranous; scutum triangular, occludent margin straight, with large teeth, tergal margin straight; tergum narrow, scutal margin long, straight, basiscutal angle oblique, spur pronounced. Maxilla subtriangular (Fig. 29 A), inferior and superior margins setose; maxillule with cutting edge notched, 2 long, cuspidate setae above notch, 3 fine short setae in notch, 12 fine setae below notch (Fig. 29 B); mandible with 4 teeth, first separated from remainder (Figs 29 C, G), lower margin smooth (Fig. 29 E), inferior angle sharp (Fig. 29 E); mandibular palp rectangular, apex blunt, dense setae on superior margin and distally (Fig. 29 D); labrum concave, deep notch absent, cutting edge with fine bidentate and tridentate teeth (Fig. 29 H). Cirrus I with rami unequal, outer ramus shorter, 11 segmented, inner ramus longer 11-segmented (Fig. 30 A); cirrus II with rami subequal, outer ramus 14-segmented, inner ramus 13-segmented (Fig. 30 B); cirrus III with rami subequal, outer ramus 37-segmented, inner ramus 43-segmented (Fig. 30 C); intermediate segments of cirri IV–VI with 2 pairs of long setae (Fig. 30 D).

Distribution. South China Sea, Japan, Taiwan and the Philippines.

Remarks. This is a new record for Taiwanese waters.