Social voles from Asiatic Turkey with four different diploid numbers, associated with peculiar external and skull morphologies, are here recognized as representing four distinct species. Specimens with 2n=54 are short-tailed with robust, deep skulls and represent Microtus guentheri. The tail is longest and the skull shallowest in voles where 2n=62, here considered conspecific with M. socialis. The identity of greyish voles with robust skulls, enlarged bullae and 2n=60 was not established, but possible relations with M. irani or M. schidlovskii are discussed. Two populations from central Anatolia (Konya and Amasya), which are characterized by 2n=48 and variable numbers of autosomal arms (NFa varying between 46 and 50), morphologically resemble M. socialis. Despite this, their tails are much shorter and their skulls deeper, which suggest that this population represents a species that is new to science: Microtus dogramacii sp. n. © 1999 Taylor & Francis Group, LLC.