ИСТИНА

The south-western Great Caucasus hosts a remarkable diversity of groundwater molluscan species. Among the great variety of hydrobiid snails inhabiting groundwaters of the South Caucasus, the endemic genus Tschernomorica Vinarski et Palatov, 2019 is of particular interest. Our study aimed to clarify the taxonomic position of the crenobiotic microsnails from the Western Georgia and conduct an integrative revision of this mollusks. The material for this study was collected during field trips in Samegrelo, Imereti, Racha, Guria, and Adjara in 2014–2022. More than 1000 hydrobiid specimens were sampled in a large number of cave water bodies and spring outlets. Integrative taxonomy methods were used to investigate mollusks features and phylogenetic relationships between them. Our analysis confirmed that the true biodiversity of the studied group exceeds earlier findings and revealed a presence of hidden local biodiversity within Western Georgia. As it turned out, Tschernomorica is a complex of at least 5 genera differing in their genital morphology and having the molecular support. Based on conchological, anatomical and genetic investigations, we describe three new genera and seven new species within the subfamily Belgrandiellinae Radoman, 1983, and provide their diagnostic features and distribution ranges. The data obtained allow us to more accurately estimate the time when the Caucasus ground waters were colonized by hydrobiid microsnails. The molecular chronogram indicates that the common ancestor of Caucasian representatives of this group diverged from its Balkan relatives about 5.63 Ma. This study was partially funded by the Russian Scientific Fund (project No. 21-44-04401).