ИСТИНА

Among cypriniforms, the spined loaches (family Cobitidae) are a species-rich group involved in polyploid evolution, with frequent hybridization events and complicated taxonomy due to cryptic species. In the Caspian Sea basin, cobitidid fishes are represented by the very discrete monophyletic genus Sabanejewia and representatives of two genera, Misgurnus and Cobitis, confirmed as polyphyletic groups. Sabanejewia species are free of diploid-polyploid relationships and very rarely hybridize; three endemic Caspian species, S. caspia, S. aurata sensu stricto and S. caucasica, belong to the species that are well identified by their external morphology, primarily by the color pattern; S. caspia is the most genetically divergent species of the genus. Among the Cobitis species, the most phylogenetically divergent is C. melanoleuca, which is widespread from the Don River basin in Europe to the Far East and China. This species participates in the diploid-polyploid complexes found in the Volga River drainage and hybridizes with triploid loaches to form one of the tetraploid forms. The main parental species for various polyploid forms is C. taenia, a European species found in the northern part of the Caspian basin. In contrast, other Caspian Cobitis species distributed in the southern part of the basin have never participated in the formation of polyploid forms, three of them - C. derzhavini, C. faridpaki and C. saniae - belong to the morphological group “C. satunini” and are phylogenetically related species; the last two should be classified as allopatric cryptic species. The probably extinct C. amphilekta has an unknown phylogenetic position.