Phylogenetic position of the relict South American genus Idiopyrgus Pilsbry, 1911 (Gastropoda, Truncatelloidea), with the description of two new cave species

Idiopyrgus is a relict genus of freshwater snails from Brazil traditionally classified in the family Pomatiopsidae. Herein, we use molecular data from newly acquired specimens to test that classification through Bayesian inference phylogenetic analysis. We conclude that Idiopyrgus belongs in the Gondwanan family Tomichiidae, together with the African genus Tomichia and the Australian genus Coxiella. Furthermore, we reassess currently synonymized genus- and species-level names in Idiopyrgus. The genera Hydracme and Aquidauania are considered synonymous with Idiopyrgus. The species I. brasiliensis and I. pilsbryi are restored as accepted species; I. walkeri is considered a taxon inquirendum. Two new species from caves in Bahia state are described herein: Idiopyrgus adamanteus sp. nov. and Idiopyrgus minor sp. nov.