Cladogenetic events in two relict species of Stenasellidae (Crustacea, Isopoda) from Sardinia Island (Tyrrhenian Sea) : A biochemical approach

Allozymic variation was studied in seven populations of exclusively stygobi tic relict isopods of the genus Stenasellus. Two of the seven populations b elong to different species (S. nuragicus and S. assorgiai) and were sampled in their type localities, With the exception of a population from the Su M annau cave, the remaining populations, of uncertain systematic position, we re sampled in wells from southern Sardinia. Levels of genetic divergence an d the pattern of inferred phylogenetic relationships allow us to confirm th at S. nuragicus and S. assorgiai are valid species. The populations of unce rtain systematic position are phylogenetically related to these two species . Phylogenetic relationships are discussed in relation to the divergence ti mes deducible from genetic distance data in order to assess the congruence between evolutionary events and Sardinian palaeogeographical dynamics.