First record and DNA barcodes of the invasive blue-coloured spiny-cheek crayfish

This contribution presents first record of a blue colour morph of spiny-cheek crayfish, Faxonius limosus (Rafinesque, 1817). Two unusually coloured individuals were caught in Poland, in two different locations, separated from each other by approximately 500 km and belonging to different river catchments (Oder and Vistula), within the range of the species occurrence in Europe. Taxonomic identification of collected crayfish has been confirmed by the standard DNA barcoding procedure. Although blue coloured forms of crayfish have been previously described within the Cambaridae family, collected individuals are the first records of blue colouration within F. limosus. It is recommended to supplement identification keys with a new colour form of the species, which, while characteristic dark red bands are not clear, may cause mistakes in recognition of exotic, aquarium as well as native species.