Discrimination des crânes du campagnol des champs, Microtus arvalis (Pallas) et du campagnol souterrain, Pitymys subterraneus (de Sélys Longchamps) en l'absence de mandibule

1799 skulls of common vole and 535 skulls of pine voles from different Belgian populations have been studied in three aspects: i) the pattern of the nasal-frontal and premaxillary-frontal sutures. This pattern is an excellent criterion by which identify the both species, and it is almost always accurate. ii) the value of ratios between a skull's height and the length of its diastema. This technique enables one to discriminate between common vole specimens with ratios above 95 % and pine vole specimens below 86%. iii) the width of the interorbital constrition. This seems to be an equally good criterion of identification, even for young animals. Hovewer, in Europe, it seems to have a clinal variation, a finding which should be verified. For the Belgium populations studied, the values for the common vole range from 2.60 to 3.50 mm (mean 3.09 mm). In the pine vole they range from 3.30 to 4.00 mm (mean 3.65 mm).