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In this study, we re-examine the Darevskia parvula group comprehensively using morphology, osteology and mitochondrial phylogeny, and describe a new endemic species from Turkey: Darevskia tuniyevi sp. nov. A total of 257 adult specimens were evaluated for external morphology (scalation and biometry) with univariate (descriptive statistics and ANOVA with post-hoc tests) and multivariate (Discriminant Analysis and ANOSIM) analyses. In parallel, osteological data and molecular analyses using three DNA markers (mitochondrial 16S rRNA and Cyt-b, nuclear Rag-1) were used to complete the description of the new taxon. The molecular phylogenetic analyses indicated that the D. parvula group is composed of three taxa as D. parvula, D. adjarica and D. tuniyevi sp. nov., and showed that D. adjarica and D. tuniyevi sp. nov. are reciprocal sister taxa. On the other hand, D. adjarica is morphologically very different from other two forms, while D. parvula is hardly distinguishable externally from D. tuniyevi sp. nov. Therefore, we can consider that D. parvula and D. tuniyevi sp. nov. are cryptic species. These two cryptic species retain their primitive morphology within the group, while D. adjarica has changed, perhaps due to different bioclimatic conditions in its Pleistocene refuge and current area.

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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.