A Note on the Distribution and Geographical Variation of the Gray-sided Vole ( Clethrionomys rufocanus Sund., 1846-1847) in Mongolia

In this paper, we present a new distribution record for the Gray-sided vole found in an isolated birch forest in southern Mongolia, at Ih Bogd mountain. This represents a very remote and isolated population of this species from its main range of forested areas. Morphological characters were used to determine the morphological variation of Gray-sided vole in the investigated southern population in comparison with two other populations: one from Honin nuga (Hentii mountain range) and the other from Hangai mountains. We revealed fi ve distinct morphotypes based on the fur coloration patterns. Two morphotypes were found in the isolated Ih Bogd population, while there were two morphotypes for the Hentii and one for the Hangai population. Moreover, based on the nine standard skull measurements, we found a marginally signi fi cant difference among the three populations, indicating that there are detectable differences. However, the discriminant function analysis was moderate in classifying the three populations. This small variation may be explained by our limited sample sizes (6-15 individuals per population) and possibly by the fact that the southern population of this species may have been isolated only for a short time