New Records of the Alien Chinese Ricefish (oryzias Sinensis) and Its Dispersal History Across Eurasia

The diversity of biota in different parts of the planet has demonstrated dramatic changes within the last several decades due to the extinction of native taxa and the appearance of invasive taxa. The correct taxonomic identification of non-native species is important for understanding their dispersal abilities, especially when potential invaders may be of closely related species. Information on the species identity of ricefish (Oryzias spp.), which have formed self-sustainable populations in some parts of Eurasia, is contradictory. In this paper, we studied samples from non-native populations of Oryzias from several Eurasian regions. The results of our mtDNA COI partial sequence study confirm that the individuals we studied belong to the species Chinese ricefish, O. sinensis. Analyses of the literature and our own data suggest that all known alien populations of Oryzias in continental Eurasia belong to the same species, O. sinensis. A recent finding of O. sinensis in the Don delta suggests that one of the species’ secondary dispersal pathways could run from the Kuban region through the lower part of the Don basin to the Cis-Azov area.