For a long time, the evolution of West Siberian zokors remained poorly covered. In this paper, we present a description of the evolution of the West Siberian zokor lineage (Myospalacinae, Rodentia) from the late early Pleistocene to the present along with descriptions of two new species and one subspecies (Myospalax myospalax krukoveri n. ssp., Myospalax convexus n. sp., Prosiphneus razdoleanensis n. sp.) ancestral to the extant Myospalax myospalax (Siberian zokor). We also reveal differences in the ontogeny of molars of modern species that were not previously detailed. These differences, together with paleontological data, indicate that in the West Siberian lineage, peramorphosis occurred in the structure of the chewing surface (with the exception of the lower m1), whereas in all other zokor lineages, there was pedomorphosis. On the basis of this pattern, we propose to split the genus Myospalax, with the separation of Myospalax myospalax and its rootless ancestral forms (Myospalax myospalax krukoveri and Myospalax convexus) into a separate genus.

Zokors (Myospalacinae) continue to be the center of systematics discussions. Phylogenetic schemes based on molecular data do not always agree with each other, nor can phylogenetic schemes based on paleontological material be complete due to the only-partial description of West Siberian zokors. This paper tries to fill this gap and presents a description of the West Siberian lineage from the late early Pleistocene to the present, together with an analysis of molar development in other zokor lineages. We describe two new species and one subspecies (Myospalax myospalax krukoveri n. ssp., Myospalax convexus n. sp., Prosiphneus razdoleanensis n. sp.) ancestral to the extant Myospalax myospalax Laxmann, 1769. We also reveal differences in the ontogeny of molars of modern species that were not previously detailed. These differences, together with paleontological data, indicate that in the West Siberian lineage, peramorphosis occurred in the structure of the chewing surface (with the exception of the lower m1), whereas in all other zokor lineages, there was pedomorphosis. On the basis of these results, we suggest a new view on the systematics of Myospalacinae.