Figures 19 A–C urn:lsid:zoobank.org:act: B6C52DEE-CFE6-4858-9013-AE5100D4E120
Type locality: SW of Buldir Island, Aleutian Is., Alaska (52°18.5 N, 175°49.0 E), 325 m (NMFS 23-199701 - 243).
Type: Holotype, LACM 3588, 35.6 mm (leg. RNC 9 Aug. 1997); Paratypes: Pt 1–3, LACM 3669, 20.8–29.5 mm. SW of Agattu Island, Near Ids. (52°13.5 N, 173°27.8 E), 169 m (NMFS 23-199701 - 229); Pt 4, SBMNH 169015, 33.4 mm. SE of Buldir Island (51°24.6 N, 175°20.0 E), 187 m (NMFS 94-200201 - 158); Pt 6, USNM 1606664, 35.1 mm. SE of Buldir Island (51°24.6 N, 175°20.0 E), 187 m (NMFS 94-200201 - 158); Pt 7, RNC 4711, 40.0 mm. (Type locality).
Referred material: RNC 4888, 1 sp., 36.8 mm. SW of Agattu Island, Near Ids. (52°13.5 N, 173°27.8 E), 169 m (NMFS 23-199701 - 229); RNC 4901, 15.34 mm. ESE of Buldir Island (52°20.61 N, 176°22.79 E), 227 m (23- 2000-01-173).
Description: Small for genus, height to 40.0 mm; suture moderately impressed, whorls rounded. Protoconch, one whorl, 3.7–4.1 mm in diameter, with four spiral cords; teleconch with three whorls; spiral sculpture of very fine lirae, with slightly wider interspaces, about 30 on penultimate whorl, and continuing on below the suture. Aperture a little more than half of shell height, outer lip flared; canal short, broad. Operculum small, less than half of aperture height.
Radula: Typical for subfamily, rachidian tooth with four subequal cusps; lateral teeth with two large, heavy cusps, outer cusp strongly curved, inner cusp straight.
Remarks: This is the smallest known species of Volutopsius, and probably cannot be confused with any congeners. Volutopsius middendorffi (Dall, 1891) is similar but much larger, reaching over 11 cm, and has a pinkish protoconch.
Etymology: Named for its small size, from the Latin nanus, dwarf. Volutopsius nanus is considerably smaller than all other known Volutopsinae.
Distribution: This small species is restricted to the western-most Aleutians, from the vicinity of Buldir Id. (176°22 E) to Attu Id. (173° E), at depths of 169– 325 m.
Habitat: Lives on black sand and gravel, at temperatures of 3.6°–4.1° C.