A biogeographical analysis of terrestrial isopods (Isopoda, Oniscidea) from the central Aegean islands (Greece)

Abstract

Terrestrial isopods (Isopoda, Oniscidea) of forty-three central Aegean islands and islets are analysed from a biogeographical point of view. The oniscid fauna consists of sixty-nine species, thirty-two genera anti fourteen families anti is characterized by Aegean elements that have an eastern Mediterranean origin. Endemism is at the level of 20%, similar to that of oniscids from other Mediterranean archipelagoes. Analysis of species distribution through both idiographic and quantitative approaches (faunal similarity among islands using Jaccard's index, simple matching indices and the UPGMA clustering technique) resulted in the recognition of a major disjunction between Kyklades-plus-Ikaria and eastern islands-plus-Astypalca and four noteworthy island groups: the eastern islands, Naxos-Ikaria, Amorgos, and all other Kyklades. Island similarities are generally consistent with the known palaeogeography of the area with the exception of Ikaria's placement with Naxos among the Kyklades. Also, the 'eastern' character of Astypalea is in conflict with evidence from other known taxa.