Morphological and genetic traits of the first invasive population of the Asiatic clam Corbicula fluminea (O.F. Müller, 1774) naturalized in the Volga River Basin.
Variability of the first invasive population of C. fluminea (O.F. Müller, 1774) from the Volga basin is studied using the mitochondrial cytochrome c oxidase subunit I gene fragment (COI mtDNA), and morphological features of the shells are characterized. A comparison with C. fluminalis (O.F. Müller, 1774) from the Kura River basin is made in order to avoid errors in species identification. All analyzed individuals belong to the most widespread R morphological type. The only nucleotide sequence haplotype we found is identical to the widespread variant prevailing in the populations of Corbicula with R morphological type in Europe and also in America. There were mollusks of different shell size groups in the sample. Corbicula larvae were detected in qualitative zooplankton samples and in the gills of adults. Therefore, the studied population reproduces independently and may possibly become a source for further species expansion.