A biogeographical analysis of Greek Oniscidean endemism

Despite our incomplete knowledge of Creek Oniscidea, a great number of spec ies have already been described, of which 69% are endemic. This unusually h igh percentage of endemics is a result of intense speciation triggered by t he complex topography, paleogeography, and ecological history of Greece. Us ing 100 x 100 km Universal Transverse Mercator (UTM) squares as Operational Geographic Units (OGUs), we mapped the presence of all endemic species kno wn until 1995, and applied Parsimony Analysis of Endemicity (PAE) in order to find patterns of OGU relationships. In the procedure, we reduced the ori ginal data matrix in two successive steps, excluding uninformative and prob lematic species and OGUs. We analyzed separately the endemic species of the large genus Armadillidium, following the same procedure. The results lead to the recognition of two main biogeographic entities, the mountainous cont inental and the insular Aegean. These groups, and the relationships of OGUs on a finer scale, do not fully agree with the established paleogeography o f Greece. Ecological factors, such as climatic change during the Pleistocen e glaciations, must have played an important role in the shaping of modern patterns. This is also supported by the results of PAE for Armadillidium sp ecies, which are indicative of a recent ecologically induced pattern of dif ferentiation.