EN
The aim of the study was the identification of molecular taxonomic marker, to differ Arion species especially A. lusitanicus, A. rufus and A. ater ater. A comparative analysis of the nucleotide sequence within the nuclear (18S rRNA, ITS1, 5.8 SrRNA, ITS2, 28S rRNA) and mitochondrial DNA (cox1) on the basis of own research and data obtained from The GenBank for different species of slugs of the genus Arion was conducted. Mitochondrial genes are suitable for taxonomic identification much better than nuclear DNA. In the case of the species A. lusitanicus a surprisingly large intraspecific variation due to a Spanish population was observed, which strongly suggests the presence of a distinct species in that site.