Taxonomic revision of the fossil genera Bulimactaeon, Hemiauricula (= Liocarenus) and Nucleopsis, with description of a new Recent genus and species (Gastropoda: Heterobranchia: Acteonidae)

Abstract

The genus Liocarenus (Acteonidae) was originally described from Eocene fossil material and has subsequently come to include three subgenera (Liocarenus s. s., Bulimactaeon and Nucleopsis) and nine species, including a Recent one (L. globulinus). Together, these have been accorded status as a subfamily, Liocareninae. We here present a taxonomic revision of all the species and subgenera historically ascribed to Liocarenus. We show that the genus name Liocarenus is an objective synonym of Hemiauricula. All three taxa (Bulimactaeon, Hemiauricula and Nucleopsis) are accepted at genus level and a new genus, Rapturella, is erected for the Recent species. Rapturella is diagnosed by a thick shell with rounded whorls, slightly stepped spire, two closely spaced subsutural spiral grooves, a weak columellar fold and a tooth-like palatal thickening. Three of the formerly included species of Liocarenus are here excluded from the Acteonidae. The revised classification is as follows: B. bernayi (Cossmann, 1892), H. edentula (Férussac, 1821), H. hilarionis (Bayan, 1870) n. comb., N. subvaricatus (Conrad, 1860), R. globulina (Forbes, 1844) n. comb. and R. ryani n. sp. (Acteonidae); Hamlinia eliai (Shalem, 1928) n. comb. and Globiconcha formosa (Cragin, 1893) n. comb. (Cylindrobullinidae); Ringicula lata (Conrad, 1865) n. comb. (Ringiculidae). Acteon costellatus Conrad, 1833 is considered a species inquirenda.