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Genetic diversity, phylogenetic position and morphometric analysis of Astacus colchicus (Decapoda, Astacidae): a new insight into Eastern European crayfish fauna.

The phylogeny of European crayfish fauna, especially with respect to Eastern European species, is still far from being completely resolved. To fill this gap, we analysed most of the European crayfish species focussing on the phylogenetic position of the endemic crayfish Astacus colchicus Kessler, 1876 inhabiting Georgia. Three mitochondrial and one nuclear marker were used to study evolutionary relationships among European crayfish species, resulting in the unique phylogenetic position of A. colchicus indicating independent species status to A. astacus (Linnaeus, 1758). Phylogenetic analyses revealed a deep molecular divergence of A. colchicus in comparison to A. astacus (6.5-10.9% in mtDNA and 1.1% in nDNA) as well as to Pontastacus leptodactylus (Eschscholtz, 1823) and P. pachypus Rathke, 1837 (5.5-10.0% in mtDNA and 1.4-2.4% in nDNA). Absent ventral process on 2nd male pleopod and abdominal somites II and III with pleura rounded and no prominent spines clearly indicate taxonomic assignment to the genus Astacus, however the species is distributed almost in the middle of Ponto-Caspian area typical by occurrence of the genus Pontastacus. Several morphological indices linked to head length, carapace and total body length and width were found to demonstrate apparent differences between A. colchicus and A. astacus. Although this study provides a novel insight into European crayfish phylogeography, we also point out the gaps in comprehensive study of the P. leptodactylus species complex, which could reveal details about the potential species status of particular species and subspecies within this genus. This article is protected by copyright. All rights reserved.