Castaneobuccinum clinopsis Mclean & Clark 2023, n. sp.

Castaneobuccinum clinopsis n. sp.

Figures 21. G–I urn:lsid:zoobank.org:act: A2CDD97A-BDB8-4C45-A7EA-F2D4C495429B

Type locality: SE of Agattu Island, Near Ids., Aleutian Is., Alaska (51°52.0 N, 174°55.6 E), 157 m. (NMFS 143- 200401 - 86).

Type material: Holotype, LACM 3592. R/ V Sea Storm (leg. R. N. Clark, 29 June, 2004); Height 79.3 mm; Paratypes: Pt 1, SBMNH 169018, 81.2 mm. Petrel Bank, Rat Ids. (52°09.58 N, 179°42.62 E), 92–94 m. (94-199401- 153); Pt 2, SBMNH 169019, 89.3 mm. Adak Island, Kagalaska Strait, Andreanof Ids. (51°45.35 N, 176°25.43 W), 11m. (AKALE07-A0021); Pt 3 & 4, RNC 4624, 73.4 & 83.7 mm. Lucky Point, Kuluk Bay, Adak Island, Andreanof Ids. (51°51.9 N, 176°35.36 W), 13 m.

Referred material: 6, RNC 4693, 18.2 –86.0 mm. Adak Island, Kagalaska Strait, Andreanof Ids. (51°46.5 N, 176°25.43 W), 12–15 m; 1, RNC 4567, 57.3 mm. S of Atka Island, Andreanof Ids. (51°52.4 N, 174°31.9 W), 146 m.

Description: Shell relatively large (to 90 mm), sturdy, tall spired; chestnut brown to cream; protoconch with 2 whorls teleconch with 6–7 whorls, suture moderately impressed; axial sculpture lacking or represented by 16–20+ low, folds on shoulder; spiral sculpture of narrow, well-defined shoulder cord, and one lesser subsutural cord; surface smooth or with finely incised spiral striations of slightly irregular spacing. Aperture large, oval, more than 1/3 of shell height; lip inflated, forming broad shallow sinus on upper part of whorl; lip edge massively reinforced.

Radula: typical for genus, rachidian tooth with 5 sub-equal cusps, the outer two slightly thicker and set back somewhat from the medial three; Lateral teeth large, tricuspid, outer cusp very large, strongly curved; central cusp much smaller, curved, separated from inner cusp by a deep notch; inner cusp shorter and broader than outer cusp, about twice as long and three times as broad as central cusp.

Remarks: This may prove to be two similar but distinct species. Specimens from the Near Islands (type locality) tend to be thinner shelled and have less coarse spiral ribs, and lack the shoulder undulations present in many specimens from the central Aleutians. The two well-spaced spiral ribs separate this species from its congeners.

Etymology: From the Greek clino, “slope” in reference to the shoulder.

Distribution: Central and western Aleutian Islands, from Petrel Bank, NE of Semisopochnoi Island, Rat Ids. (178°W) to Near Islands (172°E), at depths of 5– 180 m.

Habitat: found on sand gravel and cobble bottoms, with bottom temperatures of 3.3–5.3°C.