A biogeographical analysis of the tenebrionid beetles (Coleoptera, Tenebrionidae) of the island of Thasos in the context of the Aegean Islands (Greece)

This research aimed to study the origin and the biogeographical relationships of the tenebrionid beetle (Coleoptera, Tenebrionidae) fauna of the island of Thasos, with reference to the other Aegean Islands. A total of 32 Aegean Islands and 170 taxa (species and subspecies), 23 of which occur on Thasos, were included in this study. Nine tenebrionid species are here reported for the first time from Thasos, including the first records of Platydema europaeum and Nalassus plebejus from the Aegean Islands. Several models (linear, exponential, power, logistic, Gompertz, Weibull and Lomolino functions) were used to test the species - area relationship. The power function appeared to be the most appropriate model and the parameters of the curve suggest a possible relict character for this fauna. The proportion of Balkan taxa on the islands sharply decreases from west to east, whereas the Anatolian taxa follow an opposite trend. Multi-dimensional scaling, Parsimony Analysis of Endemicity and discriminant function analysis revealed a clear faunal discontinuity between the western and central Aegean Islands on one side, and the islands close to the Anatolian coast on the other. This discontinuity, consistent with the persistence (from Messinian to Pleistocene) of a sea barrier between these two groups of islands, strongly supports the importance of Pleistocene island configurations in determining present distributional patterns. The comparative richness of the tenebrionid fauna on Thasos is enhanced by the proximity of the island to the mainland and the diversity of its surviving habitats.