A systematic and biogeographical study of hypogean and epigean populations of the Proasellus coxalis group from Sardinia, Central Italy and Jordan: allozyme insights.

Genetic variation at 18 enzymatic loci was investigated in 10 epigean and three hypogean populations belonging to the Proasellus (Asellidae, Crustacea) species group, from Sardinia, central Italy, and Jordan, in order to clarify their systematics and evolutionary relationships. We found unexpectedly high levels of genetic divergence, which allowed us to recognize a number of genetically distinct species presently hidden under the name Proasellus coxalis. The group of Sardinian populations is the most genetically differentiated. Among the central Italian populations, the northernmost population is the earliest branch in the proposed phyletic scheme, whereas the remaining populations are genetically homogeneous and clustered as the sister taxon of the Sardinian populations. The Jordanian population is genetically differentiated versus both the central Italian and Sardinian groups. The evolutionary relationships seem to indicate that several waves of colonization by this genus occurred in Europe. The evolutionary times inferred from genetic distance data place the main splitting events at the end of the Miocene, in agreement with the paleogeography of the study areas.