Genetical and morphological variability of the greater blind mole rat Spalax microphthalmus and phylogenetic affinities of large-bodied spalacids (Rodentia, Spalacidae) with a description of Spalax lyapunovae sp. nov. from the North Caucasus

The greater blind mole rat S. microphthalmus is the only species that differs in the number of chromosomes (2n = 60) from the other species (2n = 62) of the genus Spalax. It also has the largest range among them. The intraspecific genetic and morphological variability of S. microphthalmus has been poorly studied so far. Previously, animals with 2n = 62 were found in the North Caucasus. This was interpreted as a manifestation of intraspecific polymorphism in greater blind mole rats. We investigated the morphometry, as well as the morphological, molecular, and chromosomal variability of S. microphthalmus using samples collected from across the entire range of the species. Genetic variability of S. microphthalmus was relatively low within the 2n = 60 karyotype range. A comparative, multi-proxy analysis of the species characteristics, as well as phylogenetic analyses within the genus Spalax was also performed. Species-level differences were found in all the characteristics studied in the karyotype of the blind mole rat (2n = 62) from the North Caucasus, compared with all the other Spalax species, including S. microphthalmus. A unique combination of morphological characteristics was described for this blind mole rat, including features that bring it closer to the hypothetical ancestor of all modern species of this genus. A new species is described on this basis: Spalax lyapunovae sp. nov. It is necessary to further study the range and the ecology of the new species, which is endemic to the central part of the North Caucasus.