Beringius bisulcatus Mclean & Clark 2023, n. sp.

Beringius bisulcatus n. sp.

Figures 10 A–D urn:lsid:zoobank.org:act: B8930F25-B8C4-487E-B676-74AEC4611762

Type locality: Tanaga Bay, Tanaga Island, Andreanof Ids., Aleutian Is., Alaska (51°44.5 N, 178°07.68 W), 95 m (NMFS 23-199701 - 137).

Type material. Holotype: LACM 3573, 100.9 mm. (leg. RNC, 14 July, 1997, trawled, R/V Dominator); Paratypes: Pt 1, LACM 3610, Tanaga Pass, SW of Tanaga Island, Andreanof Ids. (51°44.31 N, 178°09.16 W), 88 m (NMFS 23-199701 - 132); Pt 2, SBMNH 169003, S of Tanaga Island, Andreanof Ids. (51°33.91 N, 178°04.93 W), 183m. (143-200401-112); Pt 3, RNC 4475, 115.0 mm, Type locality.

Referred material. RNC 4802, 2 sp., 42.0 & 27.5 mm, (Topotypes).

Description: Shell of moderate size (to 115 mm, RNC 4475), pyriform, whitish, aperture often tinted light brown; periostracum relatively thick, adherent; protoconch with 2.5 whorls, 4.5 teleconch whorls; final whorl with 13–20 prominent axial ribs, interspaces broader than ribs; spiral sculpture of several faint to moderately strong cords, forming low knobs where they intersect the axials; axial ribs interrupted by broad spiral channel above the suture, another of lesser width below the shoulder, and sometimes an even narrower one closer to the sutural channel; base with five to seven cords; spiral micro-sculpture lacking; axial micro-sculpture limited to growth lines. Aperture large, canal short, broad. In paratype three (Fig. 10 B), the spiral cords and sulci are more subdued than in the holotype and paratype one, and there are more numerous axial ribs.

Radula. (Fig. 36). Rachidian tooth broader than long, lateral edges rounded, anterior edge flattened, posterior edge indented. Lateral teeth tricuspid, outer cusp, long, slender, distal half curved, tapering; central cusp small, about 1/5 or less the length of outer cusp, slender, separated from outer cusp by basal notch; inner cusp about twice as thick as central one, thumb-like in form.

Remarks: In paratype three (Fig. 10 B), the spiral cords and sulci are more subdued than in the holotype and paratype one, and there are more numerous axial ribs.

This species resembles Beringius undataformis n. sp. but differs in possessing sulci, and in lacking the lamellar periostracum. The sulci, particularly the more prominent one at the suture sets this species apart from all other known Beringius.

Etymology: From the Latin for two sulci.

Distribution: Central Aleutian Islands, known only from the vicinity of Tanaga Island and Amchitka Pass (178°W to 179°10W). A short-range endemic.

Habitat: Found on black sand and gravel bottoms, at depths of 88–182 m, with a bottom temperature of about 4.3°C.