Aegus chelifer Macleay 1819, an Asian stag beetle (Coleoptera Lucanidae) invading the Seychelles Islands: a threat for endemic saproxylic species?

An Indo-Malayan stag beetle, Aegus chelifer Macleay 1819, was found for the first time in the Seychelles (Mahé, Praslin, La Digue, Cerf ) during four surveys conducted between 2006 and 2009. The species had not been recorded in previous research on the insect fauna of these islands, even in the most recent and comprehensive studies. A. chelifer now appears to be common and widespread in the granitic islands of the archipelago, especially in Mahé, suggesting that a stable population occurs at least on this island. As all the records were made after the 2004 Indian Ocean tsunami, the occurrence of the species in the Seychelles could be explained by transoceanic dispersal from South East Asia by floating tree trunks, due to the action of ocean currents on logs removed from Asia by the tsunami. Key words: Lucanidae, Aegus, Seychelles, biological invasion, tropical islands, fauna, biogeography, dispersal.