Toward assembling a taxonomic puzzle: Case study of Iranian gray voles of the subgenus Microtus (Rodentia, Cricetidae)

The voles of the subgenus Microtus, which includes six species of the socalled “arvalis” group, have always been problematic for classification. Some group members differ in chromosome number and karyotype structure and yet appear morphologically indistinguishable, while others have very similar karyotypes despite exhibiting significant morphological differences. Two “arvalis” voles from Iran, M. kermanensis and M. mystacinus, are among the least studied members of this group. Here, we used cytochrome b sequences, morphological data and all other available material in an attempt to solve the mystacinuskermanensis taxonomie puzzle. The results of the phylogenetic analysis of the cytochrome b sequences showed that M. rossiaemeridionalis, M. mystacinus and M. kermanensis form a monophyletic group that is sister to M. arvalis. Within this group, M. mystacinus appears to be more dosely related to M. kermanensis than to M. rossiaemeridionalis; therefore, M. kermanensis may be considered the junior synonym of M. mystacinus. However, these two forms differed significantly in size and molar pattern. The attribution of M. kermanensis and M. rossiaemeridionalis to one species contradicts the preliminary results of experimental hybridisation and morphological data: they differ in size, qualitative dental features and baculum structure. The obtained data showed that until comprehensive analysis based on extensive sampling is available, it is expedient to retain the species names M. mystacinus, M. rossiaemeridionalis and M. kermanensis.