Distribution of Spiders (Arachnida: Araneae) in the Zonal–Catena Matrix of the Central Kazakhstan Steppes

Spider communities (Arachnida: Aranei) have been studied in central Kazakhstan along 70° E longitude in the subzones of typical, dry, and desert steppes on catenas, including eluvial, transitive, and accumulative positions. In total, 79 spider species belonging to 33 genera and 11 families have been identified. The bulk of the spider population consists of gnaphosid ground spiders, which are typical for arid zones and arid habitats. Wolf spiders (Lycosidae) are also abundant in the study area; they are most numerous in the lower, more humid catena positions. An increase in the proportion of jumping spiders (Salticidae), as well as their taxonomic diversity in the spider population, has been observed in the direction from north to south, from typical to desert steppes. In contrast to the species richness of ground beetles (Coleoptera, Carabidae), which decreases in the series of these habitats from north to south, the number of spider species increases, and this is similar to the species richness of darkling beetles. Within the latitudinal gradient from north to south, at the upper positions of the catena, the dynamic density of spiders decreases, while the ecological diversity of spider taxocenes increases. Catena positions that are similar in faunal composition are, as a rule, also similar in the structure of the spider population. The transition from typical to desert steppes is accompanied by a decrease in the number of widespread species of subboreal distribution, and the number of species typical for steppe and semidesert habitats and for solonchaks increases.