Background. A new taxonomy of tubenose gobies of the genus Proterorhinus has been proposed recently. However, some of taxonomic hypotheses have not been confirmed by recent genetic studies or seem not to correspond with ecological features and genetic differentiation of these fishes. The aim of this paper was to test the new taxonomy through a phylogeographic analysis of the fish from 15 sites in Southern Ukraine and Russia, through analyzing the genotypes deposited in the GenBank and to define the range of those species. Materials and methods. Fin clips were sampled from 52 specimens of tubenose gobies collected from 2003 up to 2009 in 15 localities of the Ponto-Caspian basin. Genomic DNA for amplification of mitochondrial cyt b gene fragment (about 408 bp) was extracted using the Diatom®DNA Prep 100. The haplotype MedianJoining Network was constructed using the Network 4.5.1.0. software. Results. Tubenose gobies from the Black Sea basin are represented by two euryhaline species historically distributed in different areas: P. semilunaris in the north-western part of the Black Sea basin (and possibly eastern Aegean basin) and P. marmoratus in the north-eastern part. The hypothesis about freshwater and marine Black Sea Proterorhinus species seems to be not probable. The validity of endemic Crimean P. tataricus is not confirmed, several independent findings presume it to be conspecific with P. marmoratus. Some Crimean rivers and reservoirs are populated by P. semilunaris which could spread from the Dnieper River basin through the Severo-Krymskyi channel or may be accidentally introduced. The populations from the Caspian Sea and Sea of Azov basins represent the distinct evolutionary lineage of tubenose goby. But their taxonomic state should be analyzed by further molecular genetic studies of a wide scope of Caspian samples. Conclusion. The present data on the variability of the mitochondrial cyt b gene fragment in different tubenose goby populations result in revision of some previous taxonomic hypotheses in this fish group. At the same time further molecular genetic researches of Caspian populations seem to be the main tool for future development of taxonomic conclusions.

tubenose goby, cytochrome b gene, phylogeography, taxonomy, species distribution