Morphological Verification of the Subgeneric Status of the Olkhon Mountain Vole (Alticola olchonensis Litvinov, 1960, Arvicolinae, Rodentia) Based on an Analysis of Variation in the Shape of the Third Upper Molar (M3)

We compared variation in the shape of the third upper molar (M3) in 11 taxa of the genus Alticola using geometric morphometrics and morphological mapping onto a molecular phylogenetic tree. Our results confirmed the assignment of the Olkhon mountain vole, Alticola olchonensis Litvinov, 1960, to the subgenus Alticola rather than Aschizomys, as previously established by molecular genetic methods. The separation of the Olkhon mountain vole from the closely related silver (A. argentatus) and Tuva (A. tuvinicus) mountain voles in the morphospace of M3 shape variation supports its status as a distinct species. High values of the phylogenetic indices indicated a strong phylogenetic signal in M3 shape and allowed us to reconstruct evolutionary changes in tooth configuration among taxa of the genus Alticola. The resulting morphological phylogeny was largely congruent with the molecular phylogeny inferred from mitochondrial and nuclear genes.