Russia has a number of historical foci of zoonotic anthropogenic diseases. In Central Russia, the Republic of Mordovia is one of such areas, a region being known to have foci of haemorrhagic fever with renal syndrome (HFRS) and tularemia. It therefore requires continuous monitoring. The role of small terrestrial mammals as reservoirs of zoonoses has been previously proven for the region. The aim of this work is to take an integrated approach to assess the role of terrestrial and subterranean small mammals. Subterranean mammals are often not considered important reservoirs of zoonotic pathogens that cause human morbidity. Among small mammals in the wild environment, the bank vole, the yellow-necked mouse and the house mouse play important roles as vectors of zoonoses. Among wild subterranean mammals, the greater mole rat is important as a vector of tularemia and HFRS. We analyzed homogenized internal organs of these animals (lungs, spleen, kidneys). Of all samples from the greater mole rat, 83% were positive for tularemia antigens and 17% were positive forHFRS. None of the analyzed European moles had antigens of tularemia and HFRS. No double infection with both tularemia and hantavirus was detected in the subterranean mammals. Double infection was found among terrestrial mammals in the bank vole and the forest dormouse.

Among the numerous described cases of hybridization in mammals, the most intriguing are (a) cases of introgressive hybridization deeply affecting the evolutionary history of species, and (b) models involving not a pair of species but a multi-species complex. Therefore, the hybridization history of the russet ground squirrel Spermophilus major, whose range has repeatedly changed due to climatic fluctuations and now borders the ranges of four related species, is of great interest. The main aims of this study were to determine the direction and intensity of gene introgression, the spatial depth of the infiltration of extraneous genes into the S. major range, and to refine the hypothesis of the hybridogenic replacement of mitochondrial genomes in the studied group. Using phylogenetic analysis of the variability of mitochondrial (CR, cytb) and nuclear (SmcY, BGN, PRKCI, c-myc, i6p53) markers, we determined the contribution of neighboring species to the S. major genome. We showed that 36% of S. major individuals had extraneous alleles. All peripheral species that were in contact with S. major contributed towards its genetic variability. We also proposed a hypothesis for the sequence and localization of serial hybridization events. Our assessment of the S. major genome implications of introgression highlights the importance of implementing conservation measures to protect this species.

The russet ground squirrel (Spermophilus major ) is known in the literature as a numerous widespread ground squirrel species. In recent decades, a decline in its abundance was found in some parts of its range. We have assessed the condition of this species in most parts of its distribution area based on our observations and interviews with local people. Spatial, landscape and vegetation cover parameters of S. major settlements have been studied. The research results showed a decline in the number, disappearance of settlements and a decrease in suitable habitats for this species. Small and medium-sized settlements with relatively low density of burrows, associated with low grass meadow communities typical for pastures and cattle grazing, prevail among the found settlements. One of the main factors for the decline in the number and disappearance of settlements of russet ground squirrel is, apparently, a decrease of pasture cattle grazing intensity. The continuing trend of degradation of pasture ecosystems may pose a threat to the existence of this species.

The systematics of blind mole rats (Spalacinae), a group of highly specialized subterranean rodents, remain a subject of debate. Within the genus Spalax , the greater blind mole rat ( Spalax microphthalmus ) is distinguished by its unique diploid chromosome number (2n = 60 versus 2n = 62 in others) and the most extensive geographic range. However, its intraspecific variation has been insufficiently studied. Previous finding of specimens with 2n = 62 in the North Caucasus were attributed to chromosomal polymorphism within S. microphthalmus . In this study, we conducted a comprehensive analysis of morphometric, morphological, molecular, and chromosomal variation across the entire range of S. microphthalmus , integrated with a comparative analysis of the genus Spalax . Our results demonstrate that the North Caucasian populations (2n = 62) exhibit consistent species-level differences in molecular genetics (from 8% to 12% divergence in cyt b ), karyotype, and cranial morphology, distinguishing them from S. microphthalmus and all other congeners. This lineage also possesses a unique combination of morphological traits, including features that bring it closer to the hypothetical common ancestor of all modern Spalax species. Based on this integrative evidence, we describe this lineage as a new species: Spalax lyapunovae sp. nov ., increasing the number of extant Spalax species to nine. This newly recognized species, endemic to the central North Caucasus, requires further ecological and distributional studies. Given its presumably limited range, an urgent assessment of its conservation status is warranted.