A refined method for craniometrical identification of the sibling vole species Microtus arvalis and Microtus rossiaemeridionalis in Europe and the Asiatic part of Turkey

On the basis of karyologically identified individuals of the common vole Microtus arvalis and the sibling vole Microtus rossiaemeridionalis from Europe and the Asiatic part of Turkey, a canonical craniometric classification function for the differentiation of these sibling species was worked out. The function is sex-independent and includes four craniometric parameters measured in millimeters (Y= 3.026 *Cranial height between bullae ossae + 2.811* Alveolar length of upper molars – 0.470* Zygomatic width – 2.281* Length of incisive foramen – 20.365; with centroids -1.135 for M. arvalis and 1.977 for M. rossiaemeridionalis). It shows high statistical reliability and classifies correctly 97.8% of the initial samples of karyologically determined specimens. Тhe proposed function for craniometrical identification of the sibling vole species M. arvalis and M. rossiaemeridionalis offers a new opportunity to analyze the distribution of these species. The function provides the means for outlining the species’ ranges not only in Europe, but also in the Asiatic part of Turkey, through examination of the massive amount of cranial material of the sibling species from zoological collections of numerous countries.