Bathyacmaea Okutani, Tsuchida, and Fujikura, 1992

Kaim, Andrzej, Jenkins, Robert G. & Hikida, Yoshinori, 2009, Gastropods from Late Cretaceous Omagari and Yasukawa hydrocarbon seep deposits in the Nakagawa area, Hokkaido, Japan, Acta Palaeontologica Polonica 54 (3), pp. 463-490 : 467

Genus Bathyacmaea Okutani, Tsuchida, and Fujikura, 1992

Type species: Bathyacmaea nipponica Okutani, Tsuchida, and Fujikura, 1992 , by monotypy; Recent , Sagami Bay, Japan .

Discussion.—The genus concept is based mainly on radula characters ( Sasaki et al. 2003). The shells of Bathyacmaea are rather similar to shells of Pectinodonta Dall, 1882 and the only, although rather tenuous difference lies in the central position of the apex in Serradonta while in Pectinodonta it is rather subcentral anteriorly. Therefore, without knowledge of the radula the delimitation is difficult. Both genera have species with robust cancellate ornamentation but Sasaki et al. (2003) also described B. tertia Sasaki, Okutani, and Fujikura, 2003 with a smooth shell.

Stratigraphic and geographic range.—Recent hydrothermal vents and hydrocarbon seeps in the Western Pacific. Upper Cretaceous hydrocarbon seep deposits in Japan.