Trianguloscalpellum weltnerianum (Pilsbry, 1911)

Figures 1 H, 11

Scalpellum weltnerianum Pilsbry, 1911: 64, pl. 9 figs 5–7.

Trianguloscalpellum weltnerianum . — Zevina, 1981: 306, fig. 230.

Material examined. CEL-BB-88, 1 specimen, Stn. CP320 (20º50.090’N, 117º27.170’E, 19 Aug. 2005, depth: 720–730 m), CL 8.31 mm, CW 3.57 mm, PL 3.56 mm.

Diagnosis. Capitulum elongated, length twice width; 14 capitular plates, white, surfaces sculptured with radial fine riblets, setae absent; rostrum oval, large; inframedian latus narrow, triangular; peduncle covered with strongly imbricating, laterally interlocking, white scales.

Description. Capitulum elongated, length twice width; 14 white capitular plates, surfaces striated with radial riblets (Fig. 1 H); tergum higher than wide, quadrangular (Fig. 1 H); scutum quadrilateral, umbo apical, occludent and basal margins straight, intersecting at right angles (Fig. 1 H); upper latus quadrangular, higher than wide, scutal margin concave, basal margin short (Fig. 1 H); inframedian latus triangular, height twice width, umbo apical; carinolatus upwardly curved, umbo apical (Fig. 1 H); rostrolatus quadrangular; rostrum large, oval; carina bowed, roof flat (Fig. 1 H). Peduncle covered with strongly imbricating, laterally interlocking, white scales. Maxilla subquadrangular, bilobed, setae clustered into 3 regions (Fig. 11 A); maxillule with cutting edge narrow, notched, 4 large cuspidate setae above notch, notch naked, 5 cuspidate setae below notch (Fig. 11 B); mandible tridentate, first tooth separated from second and third, lower margin very short, inferior angle pectinated with cuspidate setae (Fig. 11 C); mandibular palp with setae apically and along superior margin, inferior margin naked (Fig. 11 D). Cirrus I with rami unequal, separated from cirri II–VI, outer ramus longer, slender, 10-segmented, inner ramus slightly broader, 6-segmented (Fig. 11 E); cirri II–VI long, slender; cirrus II with outer ramus 12-segmented, inner ramus 12-segmented (Fig. 11 F); cirrus III with outer ramus 12-segmented, inner ramus 11-segmented; cirrus VI with outer ramus 14-segmented, inner ramus 15-segmented (Fig. 11 G); caudal appendage very short, 1-segmented, length <basal segment of pedicle of cirrus VI (Fig. 11 H).

Distribution. Japanese and Taiwanese waters.

Remarks. This record of T. weltnerianum is a new record for Taiwanese waters. Pilsbry (1911) noted that T. weltnerianum is morphologically close to T. album (Hoek, 1883) collected from the Malay Archipelago. Trianguloscalpellum weltnerianum differs from T. album in having the surfaces of the capitular plates striated, whilst those of T. album are smooth (Hoek, 1883; Pilsbry, 1911). At present, this species is only reported to live on crinoids, suggesting an association relationship.