Castaneobuccinum orri Mclean & Clark 2023, n. sp.

Castaneobuccinum orri n. sp.

Figures: 21 A–C urn:lsid:zoobank.org:act: B22E8952-8D0E-4E9B-AF87-EC4A05D62959

Type locality: N of Cape Shaw, NE side of Atka Island, Andreanof Ids., Aleutian Is., Alaska (52°22.55 N, 173°58.60 W), 80 m. (Rae Baxter, sta. 86–317).

Type material: Holotype, LACM 3590 (leg. Rae Baxter, 6 August, 1986). 53.8 mm; Paratypes: Pt 1, SBMNH 169017, 56.5mm, Adak Island, Andreanof Ids. (51°45.35 N, 176°25.43 W), 11 m (AKALE07-A0021); Pt 2, RNC 4554, 61.0 mm. Adak Island, Andreanof Ids. (51°45.35 N, 176°25.43 W), 11 m (AKALE07-A0021).

Referred material: 1, RNC 4219, 43.3 mm. Petrel Bank (52°04.15 N, 179°41.63 E), 74 m (NMFS 143-201001 - 146); 1, RNC 4072, 10.5 mm. W of Tanaga Island (51°44.5 N, 178°07.68 W), 95 m (NMFS 23-199701 - 137); 1, RNC 4023, 54.6 mm. S of Atka Island (51°52.62 N, 174°33.61 W), 147 m (NMFS 23-199701 - 95).

Description: Shell moderately large (to 61 mm, RNC 4554), sturdy, tall spired; chestnut brown. Protoconch with 2.5 whorls; teleconch with five or six whorls, suture well impressed; axial sculpture lacking; spiral sculpture consisting of a single (often nodulose) mid-whorl cord, beginning as a carination, in the early teleconch, and numerous fine spiral incisions. Aperture large, oval, much less than half of shell height. Outer lip inflated, heavily reinforced, forming broad shallow sinus on upper part of whorl; canal very short, broad.

Radula: Rachidian tooth broad, rectangular, bearing five spaced, equal length cusps; Lateral teeth tricuspid, outer cusp large, heavy, strongly curved, inner small, slender, only slightly curved, outer cusp much larger than inner one, slightly curved.

Remarks: The single broad spiral cord separates this species from all of its congeners.

Etymology: The name honors Dr. James W. Orr, Ichthyologist, Alaska Fisheries Science Center (retired) for his many years of assistance in securing mollusk specimens from NOAA/NMFS Alaska trawl surveys.

Distribution: Central Aleutians, Andreanof Ids., where it has been found from Atka Island (174°W) to Tanaga Island (178°W), at depths of 15– 147 m.

Habitat: Cobble and sand bottoms, at temperatures of 5.1–6°C.