Dynamics of Diversity of Spined Loaches of Genus Cobitis (Cobitidae) of Trans-Caucasus in the Anthropogenic Period According to the Data of Museum Collections. III. Morpho-genetic Variability, Taxonomic Status and Diagnostic Characters of Spined Loaches of the Black Sea Coast North of the Meskheti Ridge of the Lesser Caucasus

Based on a comparative study of the variability of external morphological characters, color features, craniological and karyological characteristics of spined loaches of the genus Cobitis from the water bodies of the Colchis Lowland, analysis of data on the geological history of the region and zoogeographical data, it was concluded that the populations of the eastern Black Sea coast north of the Meskheti Ridge of the Lesser Caucasus belong to an independent species C. osurgeticus . It differs from C. satunini , which inhabits the water bodies of Adjara, in the structure of the karyotype, a number of proportions of the neurocranium and individual skull bones, a shorter caudal peduncle, and the position of the dorsal fin. The revealed phylogenetic proximity of the mitochondrial genes of the two species may be associated with diploid–polyploid relationships and interspecific hybridization in the genus Cobitis and suggests the need for further studies of the populations of the eastern coast of the Black Sea, including the spined loaches of Abkhazia, for which a hybrid origin via crossing with C. tanaitica cannot be preliminarily excluded. The neotype of C. osurgeticus is designated, and the species diagnosis is presented.