The least known European native crayfish Astacus pachypus (Rathke, 1837) revealed its phylogenetic position

The thick-clawed crayfish Astacus pachypus (Rathke, 1837) is the least known species within the Astacidae, mostly due to limited access to samples and declining populations in recent decades. In the present study, for the first time, we report the phylogenetic position of this vulnerable native European freshwater crayfish within the genus Astacus, based on mitochondrial (COI and 16S rRNA) and nuclear (ITS2) molecular markers. Genetic results suggest its closest relationship is to A. leptodactylus (Eschscholtz, 1823), as previously suggested by morphology and common area of occurrence.