Geometric Morphometrics of the Cranium and Mandible in Social Voles of the “Guentheri” Group (Arvicolinae: Sumeriomys)

We analyzed the cranium dorsal projection and the mandible lateral projection in bone specimens from five Microtus guentheri and Microtus hartingi forms by geometric morphometrics (GM) methods (generalized Procrustes analysis, principal component analysis, canonical variance analysis, and discriminant function analysis). Analyses of the linear size and shapes of the cranium and lower jaw showed clear-cut differentiation among the forms into an eastern cluster and western cluster, matching M. guentheri and M. hartingi, respectively. Differences were revealed both between two subspecies of M. guentheri and between the subspecies M. h. strandzensis and Rhodopean M. hartingi, whose subspecies status has not yet been determined. M. h. ankaraensis bone specimens differ in many parameters of GM from the studied European specimens and to a lesser extent from M. g. guentheri and M. g. philistinus. Calculated morpho-ecological indices of the lower jaw revealed significant differences among all these forms, thereby possibly indicating adaptation of each to a specific habitat and dietary habits. Because of the emergence of impenetrable barriers for voles (the Anatolian Diagonal in the east and the Dardanelles and Bosporus in the west), the resultant vole groups have evolved independently.