Genetic isolation, phylogenetic relationships, and revalidation of the species Cottus kuznetzovi Berg, 1903 (Actinopterygii: Cottidae)

The fish species Cottus kuznetzovi was described by L.S. Berg in 1903 from the Lena River system. However, two years after its description, Berg synonymized this sculpin with the widely distributed species C. poecilopus Heckel, 1837. It remained a junior synonym until 2009, when this species was redescribed and revalidated. Despite this, some researchers continue to doubt the validity of C. kuznetzovi. The authors obtained new materials from the Arctic region of Eastern Siberia and the upper reaches of the Lena River. This made it possible to apply molecular genetic methods to resolve issues related to the taxonomic status and genetic differentiation of C. kuznetzovi, and also enabled the discovery of this species in new areas. As a result of the analysis of the nucleotide sequences of the mtDNA control region (CR) and the cytochrome b gene (cytb), individuals of the species C. kuznetzovi were identified in the upper reaches of the Lena River, as well as in the Aldan, Indigirka, and Yana river systems. The average p-distance (CR) between different populations was 0.97 ± 0.29%. The presented results indicate a strong genetic isolation of this species from all closely related sculpins. The average p-distances between C. kuznezovi and closely related species of the group “Cottus poecilopus” ranged from 2.50 ± 0.47% to 3.95 ± 0.63% for CR marker, and from 1.50 ± 0.35% to 7.95 ± 0.81% for cytb marker. The validity of this species has been reliably established.