Том 103, № 11 (2024)

The path taken by I. S. Darevsky to the discovery of natural parthenogenesis in rock lizards of the Caucasus (1957, 1958) is tracked, as well as his further developments of the problem of parthenogenesis in lizards in his main papers (1962, 1966, 1967) and monograph (1967). The following issues are considered: geographic and hybrid parthenogenesis, subspecies and species in unisexual lizards, spontaneous males in parthenogenetic species, the essence of I. S. Darevsky’s discovery in the context of different categories of clonal reproduction in animals, the formation of the concept of reticular speciation, and the evolutionary age of clonal forms in various groups of animals.

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.

The cold tolerance, the attitude to dissolved oxygen depletion in water, and the overwintering strategy of individuals of one of the intraspecies forms of the Oriental fire-bellied toad, Bombina orientalis f. sylvatica were studied in the south of Primorye, Russian Far East. It was revealed that individuals of the study form were unable to tolerate a decrease in the level of dissolved oxygen in water below 6 mg/l, and slightly resistant to negative temperatures (surviving only for 1–4 days at –1.1 ± 0.1°C). The main stereotype of overwintering of the Bombina orientalis f. sylvatica was confirmed to be terrestrial hibernation. Similar studies on the second form of the species, f. praticola, may by confirm the validity of the segregation these two ecological forms within B. orientalis.

We describe a new species of blind skink of the genus Dibamus Duméril et Bibron, 1839 based on five specimens collected from Bokor National Park, Kampot Province, southern Cambodia. Dibamus elephantinus sp. n. can be distinguished from its congeners by the following combination of morphological characters: snout-vent length (SVL) up to 129.3 mm; tail length comprises 17–22% of SVL; rostral suture incomplete; nasal and labial sutures complete; single postocular; three scales at the posteromedial edge of first infralabial; two scales at the posterior edge of second infralabial; the medial sublabial scale enlarged; 19 midbody scale rows; 22 transverse scale rows just posterior to head; 17–19 transverse scale rows just anterior to vent; 178–202 ventral scales; 46–52 subcaudal scales; relative size of frontal to frontonasal (FSW/FNSW) 127–136%; relative size of interparietal to surrounding scales (IPW/NSW) 111–140%; in males hindlimbs longer than head length (HLL/HL 74–78%); the light colored band on the body may be present or absent. We provide an osteological description of the new species based on micro-CT data. Genetically and morphologically Dibamus elephantinus sp. n. is most closely related to D. dalaiensis inhabiting the western part of the Cardamom Mountains in Cambodia. The new species inhabits montane evergreen forests of Damrei Range (also known as Elephant Mountains) at elevations of ca. 1000 m a. s. l. Our study brings the number of species in the genus Dibamus to 27; Dibamus elephantinus sp. n. is the second species of Dibamus to be recorded from Cambodia.