Co-occurrence of narrow-clawed crayfish (Astacus leptodactylus sensu lato) and noble crayfish (Astacus astacus L.) in the southwestern Balkans: The case of Lake Pamvotida (NW Greece)

Two individuals of the locally non-indigenous crayfish species Astacus leptodactylus (sensu lato) were collected by trapping in Lake Pamvotida (Region of Epirus, Greece). This is the first record of the species from the southwestern Balkans and particularly from the Ionian biogeographic area. It suggests that there has been a significant human-mediated expansion in A. leptodactylus territory across the Pindos cordillera. Moreover, four individuals of the species Astacus astacus (L.) were also collected from the lake. The re-occurrence of this species after at least two decades of presumed absence represents a unique known case of co-occurrence for these two species in Greece. We present a brief overview regarding the current distribution of both species (in Europe, Balkans, Greece, as well an occurrence map for Lake Pamvotida), a record of their morphometrics and a description of the main morphological characters of the captured specimens. The unexpected presence of A. leptodactylus in Lake Pamvotida suggests that it was probably transferred there or escaped from restaurant facilities situated around the lake and on Nisi Island. In the case of A. astacus, its indigenous status (i.e. specimens originating from an existing and naturally recovering population in the same lake/habitat), although questionable, cannot be disregarded until future extensive genetic work. Overall, the presence of these species in the lake could, in the long term, help to re-establish crayfishing there.