Enigmatic corkscrew-shaped Liobaicalia (Caenogastropoda: Truncatelloidea: Baicaliidae): description of three new species and their relations with regular shell species

Three new species have been added to the formerly monotypic genus Liobaicalia Martens, 1876. We employed a combination of morphological, anatomical, and molecular approaches using mitochondrial COI gene, nuclear ATP-synthase alpha subunit gene intron (ATPase), and ITS1 spacer to delineate species boundaries between Liobaicalia stiedae (W. Dybowski, 1875), L. sidelevae sp. nov., L. karabanovi sp. nov., and L. riedeli sp. nov. The Liobaicalia species inhabit burrowing into sandy substrates in disparate regions of the ancient and/or recent deltas of the inflows to the south and central Baikal basins near tectonic faults where gases discharge happens. The genus Liobaicalia was not recovered as monophyletic based on current molecular-phylogenetic analyses based on mitochondrial COI data. We discussed discordance between morpho-anatomical and genetic traits, the possible origin of the Liobaicalia species, and the occurrence of scalariform shells in Baikal and non-Baikal gastropods belonging to different families.