Neptunea petrelensis Mclean & Clark 2023, n. sp.

Neptunea petrelensis n. sp.

Figures 16 A–C urn:lsid:zoobank.org:act: 56C0C6EC-FF8A-41E1-B4EE-FC35BCB9E5C9

Type locality: Petrel Bank, NW of Semisopochnoi Id., Rat Ids., Aleutian Is., Alaska (51°59.93 N, 179°14.91 E), 143 m (NMFS 143-201201 - 136).

Type material: Holotype: LACM 3583, 74.5 mm; Paratypes: Pt 1, RNC 4984,102.8 mm Petrel Bank, NE of Semisopochnoi Island, Rat Ids. (52°16.38 N, 179°54.40 E), 101 m (NMFS 143-200401 - 122); Pt 2 & 3, SBMNH 464992, 88.0 mm & 85.4 mm. Petrel Bank, NE of Semisopochnoi Island, Rat Ids. (52°10.24 N, 176°36.06 E), 133 m (NMFS 143-201401 - 123).

Referred material: 1, RNC 4718, 54.4 mm. Milrow, Amchitka Island, Rat Ids. (51°44.3 N, 179°08.2 E), 10 m; 1, RNC 4588, 35.2 mm. Petrel Bank, Rat Ids. (52°10.5 N, 179°36.5 E), 130 m (NMFS 143-2010 - 1-149); 1, RNC 4589, 103.5 mm, S of Amlia Island, Andreanof Ids. (51°54.48 N, 173°42.4 W), 134 m; 1, RNC 5041, 38.3 mm, N of Carlisle Island, Islands of Four Mountains (52°58.6 N, 170°03.9 W), 123 m.

Description: Shell relatively small for genus (to 102.8 mm, RNC 4984); pyriform, brown with cream overtones; periostracum lacking; whorls rounded, suture moderately impressed. Protoconch large, 4.2–4.6 mm, two whorls; teleconch with four whorls, early whorls with two cords; spiral sculpture of one sharp cord at periphery and one additional cord of similar size and strength on rounded whorl above periphery; two to three cords below periphery often suppressed in development, one to five fine lirae between cords; base of whorl with 10–12 often suppressed cords. Aperture large, about half or less of shell height, oval; canal short, relatively broad.

Radula: Rachidian tooth roughly chevron shaped, strongly indented anteriorly, bearing three subequal cusps, the central cusp only very slightly longer than the others. Lateral teeth tricuspid, outer cusp twice as large as others, strongly curved, central and inner cusps about the same size, but inner cusp often longer.

Remarks: The specimen from south of Amlia Island (RNC 4589) has double cords just above and just below the suture. The three primary cords on the Amchitka Island (RNC 4718) specimen have eight coronations. This species resembles Neptunea lyrata (Gmelin, 1791), but is easily distinguished by 1) the two prominent cords on the teleconch whorls, and 2) the much larger nuclear whorls, 4.2–4.6 mm compared to 2.0– 2.8 mm in N. lyrata.

Etymology: Named for the Petrel Bank, the type locality.

Distribution: Central Aleutian Islands, from Semisopochnoi Island, Rat Ids. (179°36 E) to N of Carlisle Island, Islands of Four Mountains (170°03.9 W), 100– 143 m.

Habitat: Lives on sand and cobble bottoms at temperatures of 4.0–4.6°C.