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The study of genome size variation in cells of vertebrates using the DNA flow cytometry makes it possible to precisely determine polyploid individuals, which is extremely important when studying the processes of reticulate speciation. In addition, in many groups of vertebrates, closely related species often differ in the nuclear DNA content. Therefore, the purpose of our study was to explore the variability of genome size and ploidy in populations of 29 species and subspecies of mountain lizards of the genus Darevskia, as well as their hybrids. As a result of the study, the range of variability in individuals of different ploidy (91% of diploid and 9% of triploid individuals) was established not to overlap. Among diploid species, no correlation was found between the nuclear DNA content and phylogenetic relationships, geographic coordinates, altitude, average annual temperatures and precipitation. Representatives of all studied species complexes (with the exception of D. adjarica) had approximately the same limits of variability. Two species (D. derjugini and D. saxicola) show significant intraspecific variability. Comparisons of the genome size of parthenogenetic and bisexual species generally revealed no noticeable differences between them. Studies of triploid hybrids have shown that their genome size as a whole roughly corresponds to the sum of the average size of the diploid genome of the maternal parthenogenetic species and the haploid genome of the paternal species. The variability of genome sizes within samples of triploid hybrids was on average slightly higher than in most parthenogenetic species, but some lower than in bisexual species. The paper discusses peculiarities of reticulate speciation in this group of animals.

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A new species of rock lizards of the genus Darevskia Arribas, 1999 — Darevskia arribasi sp. nov. is described from vicinity of Ertso Lake in South Ossetia. In comparison of Darevskia arribasi sp. nov. with other species of the “saxicola-brauneri” complex [D. lindholmi (Szczerbak, 1962), D. saxicola (Eversmann, 1834), D. brauneri (Mehely, 1909) (including D. b. brauneri, D. b. myusserica Doronin, 2011, D. b. darevskyi (Szczerbak, 1962), and D. szczerbaki (Lukina, 1963)], the new species is characterized by the smallest body size among all representa- tives of this complex Lxx — 55 – 62 mm; }} — 58 – 63 mm. The number of scales around the middle of the body (Sq.) in D. arribasi sp. nov. (52 – 58, more often 54 – 56) also significantly less than for D. saxicola sensu lato in generally. Along the throat from ear to ear fold there are 36 – 42 scales, less than in D. saxicola sensu lato. Two large preanal shields present in front of the anal shield in half of the individuals examined; in a quarter of in- dividuals on both sides of the small central preanal there are by one enlarged lateral preanal shield, in another quarter all preanal shields are of the same size. Central temporal (Massetericum) always developed; always six pair of mandibulars, three in contact; collar straight, extremely rarely slightly serrated; ribs on the caudal scales are expressed to some extent; rostral usually separated from frontonasal by nasal shields. The coloration of adult males is olive-lettuce, or olive-brown from above; adult females are grey-brown; juvenile coloration coffee-brown with the blue and black spots on the edge of the outer ventral shields at the middle of trunk. Taxonomical status of new species is well supported with result of analysis of the mitochondrial cytochrome b data.