The non-marine truncatelloidean gastropods of the Late Cretaceous of Ajka, Hungary, with the description of a new genus from North America

The Cretaceous saw the first major radiation of non-marine gastropod faunas. However, many assemblages from that period are only sparsely known or have been poorly documented and described. The Upper Cretaceous (Santonian) Ajka Coal Formation in western Hungary serves as an important reference fauna and has yielded approximately 40 species of brackish-water and freshwater gastropods and another 16 terrestrial species. Here, we re-describe the five truncatelloidean Gastropoda (Caenogastropoda: Truncatelloidea: Hydrobiidae, Palaeobaicaliidae, ?Bithyniidae) introduced by Leopold Tausch in the 19th century based on his recently re-discovered type materials. We discuss systematic classification, taxonomic issues, and designate lectotypes to fix species identities. In addition, we describe a new genus and species recently recovered from the deposits, Rhaphisotostoma asztalosi Páll-Gergely & Neubauer, gen. et sp. nov. Lastly, we describe a new genus Antelopites Neubauer & Páll-Gergely, gen. nov. (type species: Parateinostoma altispirale Yen, 1951) for five species from Albian–Cenomanian deposits of Wyoming, USA, previously placed in the genus Parateinostoma Oppenheim, 1892.