Boreancistrolepis excelsus Mclean & Clark 2023, n. sp.

Boreancistrolepis excelsus n. sp.

Figures 5 B–F

urn:lsid:zoobank.org:act: D0FD5604-C34D-48A4-BA7D-C350D464604F

Type locality: S of Attu, Island, Near Islands, Aleutian Islands, Alaska (52°13.5 N, 173°27.8 E), 169 m, (NMFS 23-1997 - 01-229) (leg. RNC, 6 August, 1997, trawled, R/V Dominator).

Type material: Holotype, LACM 3570, 69.0 mm (leg. RNC, 6August, 1997; trawled, R/V Dominator); Paratypes: Pt 1, LACM 3608 (type locality), 74.4 mm; Pt 2, LACM 3609, 58.1 mm. Tanadak Pass, E of Segula Island, Rat Ids. (52°03.45 N, 178°18.94), 407 m; Pt 3, USNM 1606663, 68.38 mm. E of Kruloi Point, Agattu Island, Near Ids. (52°27.91 N, 174°13.71 E), 118 m, (NMFS 94-2002 - 01-161); Pt 4, SBMNH 46499, 64.11 mm. S of Amutka Island (52°29.46 N, 171°06.96 W), 281 m, (NMFS 176-2014 - 01-40); Pt 5, SBMNH 169000, 64.4 mm. S of Little Sitkin Island, Rat Ids. (51°52.56 N, 178°34.01 E), 407 m, (NMFS 94-2002 - 01-154); Pt 6, CASIZ 236199, 48.64 mm. Samalga Pass (52°56.1 N, 169°20.38 W), 399 m, (NMFS 143- 2004-01-23); Pt 7, RNC 4700 (type locality) 65.17 mm.

Referred material: CASIZ 149895, 1 sp., 30.38 mm, S of Islands of Four Mountains (52°20.45 N, 170°40.08 W), 224 m, (NMFS 94-200001 - 48); RNC 4522 (type locality), 3 sp., 28.19–80.78 mm; RNC 4623, 1 sp., 69.38 mm. S of Unalaska Island (53°12.0 N, 166°49.82 W), 209 m, (134- 2003-01-17); Koen Fraussen Coll., 1 sp., 67.97 mm. S of Yunaska Island (52°29.68 N, 170°41.19 W), 226 m, (NMFS 23-1997 - 01-48); RNC 4690, 1 sp., 26.86 mm. S of Seguam Island (52°03.51 N, 172°33.12 W), 145 m, (NMFS 23-2000 - 01-72); RNC 4917, 2 sp., 68.27 & 39.19 mm S of Islands of four Mountains (52°13.7 N, 169°44.7 W), 329 m, (NMFS 143-2010 - 01-72).

Description: Shell relatively large (largest examined 80.7 mm, RNC 4522), profile tall, moderately slender, whorls six (figs. 5 B–D); shell white, periostracum glossy, thin, adherent, olive green, with slightly lighter zone on the basal region, shiny, not flaking in dry shells; Protoconch one whorl; whorls rounded; irregular, sculpture of oblique, spiral cords (especially near the shoulder) very weak or absent; aperture about 40% of shell height, notch shallow; outer lip extending well below the base of the pillar, parietal callus white, well-marked but not raised; continuous lip thickening extending to the parietal shield and columella of mature shells; canal very short; Operculum (fig. 5E), convex, glossy, with terminal nucleus.

Radula (fig. 2F). Rachidian tooth broad, bearing three relatively long, sharply pointed cusps, the central cusp somewhat larger than the lateral ones. Lateral teeth long, bearing three well-spaced, sharply pointed cusps; outer denticle large, curved; central cusp about half as long as outer one; inner cusp somewhat longer than the central one, strongly curved.

Etymology: From the Latin, meaning exalted.

Distribution: Occurs throughout the Aleutian Islands, from Unalaska Island, Fox Ids. (166°49W), west to the type locality, at Attu Island, Near Ids. (173°27 E), at depths of 145– 407 m.

Habitat: Black sand and gravel, with bottom temperatures of 3.4–4.8°C.

Remarks: Paratypes agree with holotype in all characters, and individual variation is very minor, some specimens have erosion at the suture giving channeled appearance.

This genus/species bears a striking resemblance Aleutijapelion aleuticus (Dall, 1895) in its profile, and two-toned periostracum, but differs in having a glossier periostracum, convex, glossy operculum, low (not extended), nuclear whorls, and radular teeth typical of members of Parancistrolepidinae (Rachidian tooth bearing three, sharply pointed cusps, as opposed to a simple, acuspate plate in Beringiinae).

The new species also resembles Neancistrolepis glaber Habe & Ito, 1973 (fig. 5A), but differs in its smaller size (80 mm verses 130+ mm), heavier, thicker shell, and larger, glossy operculum which fills the aperture. Baxter (1987:120) reported on this species (as Beringius aleuticus Dall, 1895), stating that “ Beringius aleuticus does not belong in the genus Beringius based on its nuclear whorls and what is apparently its operculum”.