An alien species or another perspective to the freshwater gobies puzzle: a new finding in Lake Prespa

Abstract

Here we present a discovery of a new fish from the family Gobiidae in Lake Prespa, which is known as a European hotspot for biodiversity and endemism. This is the first detection of a fish species from this family, not only regarding this lake but also in the territory of the Republic of North Macedonia in general. The close examination of the recorded specimens revealed the presence of perianal organ surrounding the anus. This unique organ and various other observed morphometric and phenotypic characteristics point out to the genus Economidichthys. The two known fish species from this genus are currently considered endemic only to the rivers and lakes of western Greece. This new finding could be an evidence of alien species introduced in this lake, or an evidence of native species that are not recorded yet because of their characteristic life habits. Either way, this is a very important finding for the taxonomy and biogeographical distribution of the freshwater gobies in the Balkans.