A biogeographical analysis of Greek Oniscidean endemism

Abstract

Despite our incomplete knowledge of Greek Oniscidea, a great number of species have already been described, of which 69% are endemic. This unusually high percentage of endemics is a result of intense speciation triggered by the complex topography, paleogeography, and ecological history of Greece. Using 100 × 100 km Universal Transverse Mercator (UTM) squares as Operational Geographic Units (OGUs), we mapped the presence of all endemic species known until 1995, and applied Parsimony Analysis of Endemicity (PAE) in order to find patterns of OGU relationships. In the procedure, we reduced the original data matrix in two successive steps, excluding uninformative and problematic 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 continental and the insular Aegean. These groups, and the relationships of OGUs on a finer scale, do not fully agree with the established paleogeography of Greece. Ecological factors, such as climatic change during the Pleistocene glaciations, must have played an important role in the shaping of modern patterns. This is also supported by the results of PAE for Armadillidium species, which are indicative of a recent ecologically induced pattern of differentiation.