Craniological Divergence of Two Genetically Closely Related Caucasian Spined Loaches:Cobitis saniaeandC. derzhavini(Cobitidae)

The craniological analysis ofCobitis derzhavinifrom the Mingechaur Reservoir system andC. saniaefrom the Malyi Kyzylagach Bay drainage and the Alvady River in Azerbaijan did not reveal any fundamental differences in the general morphology of the neurocranium and cranial bones between these species, as well as from the previously studiedC. taenia,C. melanoleucaandC. taurica. However,C. derzhavinishowed high level of diversity from otherCobitisspecies in the proportions of some bones, at first, operculum. The results confirm thatC. derzhaviniis a separate species characterized by a predominance of opercular bone with weakly excised posterior margin, in contrast to opercular bone with deeply excised posterior margin observed in other craniologically studied species ofCobitisandSabanejewia.