Castaneobuccinum clinopsis, Mclean & Clark, 2023

Castaneobuccinum clinopsis View in CoL n. sp.

Figures 21. G–I View FIGURE 21 urn:lsid:zoobank.org:act:

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 ) GoogleMaps .

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

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 GoogleMaps ; 1, RNC 4567 , 57.3 mm. S of Atka Island , Andreanof Ids. ( 51°52.4 N, 174°31.9 W), 146 m. GoogleMaps

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.