The chestnut coloured shell makes B.castanea easily recognised among the arctic rissoids with spiral sculpture. Menestho albula (Fabricius, 1780) and M truncatula (Odhner, 1915) (Pyramidellidae, see WAREN 1991) invite to confusion, but their whorls are less evenly rounded and more or less shouldered, their larval shell is hypertrophic, and the spiral furrows are crossed by fine axial lamellae.
Earlier records from Norway were based on erroneous identifications (WAREN 1974), but the species is here reintroduced in the known Norwegian fauna.
Distribution Canada, Greenland, northern and eastern Iceland, northern Norway. Svalbard. western Siberia, in 10-200 m. , usually 20-60 m (mainly after WAREN 1974).