A contribution to knowledge on the terrestrial malacofauna of the Kastellorizo (Megisti) island group (SE Greece)

BACKGROUND: The Kastellorizo island group (in the Dodecanese, Greece) is situated in the southeast corner of the Aegean Archipelago. It consists of twenty islets, of which the three largest (Kastellorizo, Ro and Strongyli) and seven smaller ones belong to Greece. Knowledge of the malacofauna on the islands is relatively poor. Only eight species were known prior to the present study, all from the islet of Kastellorizo. RESULTS: Here, using the scientific collections at the Natural History Museum of Crete collected mainly by the authors and also by several researchers since 1976, we reappraise the malacofauna of the island group. Thirty-one species were found in total (23 from Kastellorizo, 19 from Ro, 15 from Strongyli, 10 from Agios Georgios, 14 from Agrielia, 6 from Psomi and 10 from Psoradia). CONCLUSIONS: The fact that there are no endemic snail species in the islands can be accounted for by their proximity to the Turkish coast, their common paleogeography with Turkey until the Late Pleistocene and Holocene, and the influence of humans. All but two species, Mastus etuberculatus and Vitrea riedeliana, are known from the adjacent Turkish coasts. Together with the subfossil species found on the smaller islets, the predominance of different species on each islet suggests a continuous substitution from the source areas of Turkey and the Aegean.