Distribution of Proteus (Amphibia: Urodela: Proteidae) and its possible explanation

Approximately 250 localities of the nominal species Proteus anguinus Laurenti 1768 have been evaluated and listed. The species is limited to the Dinaric Karst; it ranges from the Isonzo-Soĉa River in southeastern Venezia Giulia, Italy, through the southern half of Slovenia, southern Croatia, and parts of Bosnia and Hercegovina, to the Trebišnica River in eastern Hercegovina. In some regions, populations have been extinguished or endangered by pollution or human-induced hydrographical changes. The distribution of Proteus is compared with those of some cave Crustacea: Troglocaris (Crustacea: Decapoda), Monolistra , and Titanethes (Crustacea: Isopoda). The similarity of distribution patterns within this ecologically diverse assemblage supports their paleogeographic rather than ecological foundation. The paleogeographical and paleoclimatological data, in combination with the physiological requirements of Proteus, strongly suggest that these animals invaded the caves, at least in the NW parts of their ranges, only after the last glaciations, within the last 10,000 years. It is suggested that the high heterozygosity of populations can best be explained by fusion of some locally restricted immigration waves. The close morpho- logical similarity of nearly all populations of Proteus is probably due to the convergent evolution of previously differentiated populations (or even species) after their withdrawal underground.