The fauna and the landscape-biotopic distribution of weevils (Coleoptera: Curculionoidea) of the Aytuarskaya steppe (Orenburg Region, Russia)

The species composition was established and the comparative analysis of the weevil fauna (Curculionoidea) in the Aytuarskaya steppe site of the “Orenburgsky” Nature Reserve (Russia) was carried out after a long-time research (2015–2020). This territory is located at the border between Europe and Asia in the subzone of the southern steppes in low mountains of the Urals (near the border with Kazakhstan). In total, 277 species of weevils from four families were found (41% of the species composition in the Orenburg Region). Of these, 11 species were recorded for Orenburg Region for the first time, including two new records for Europe (Pseudorchestes asiaticus Legalov, 1997 and Cardipennis rubripes (Hustache, 1916)), and the yet undescribed species of the genus Eremochorus Zaslavskij, 1962. The studied fauna is characterized by a high level of species richness and originality, a large proportion of Central Palaearctic species (22%) with a significant number of Western Palearctic forms (15%), as well as the predominance of representatives of the subboreal complex (steppe and desert-steppe). The large group of weevil species (24%) is located at its distribution boundaries in the Aituarskaya steppe: eastern (31 steppe and nemoral species), southern (24 forest and meadow species) and northern (10 southern steppe and semidesert-desert forms). Species inhabiting petrophytic steppes (133 species, 48% of the fauna composition) form the basis and specifics of the weevil steppe complex of the reserve. Trophic associations of some weevil species with plants belonging to the Ural mountainsteppe endemics and relicts are established. In addition, large groups of meadow-steppe, forest and near-water species were found in the fauna, concentrating in deep intermountain ravines and in the Ural River valley. The data presented in the paper testify to the presence of significant biogeographic barriers in the Southern Urals (including its low-mountain steppe part) and emphasize the great importance of the protected Aytuarskaya steppe as a reserve of reference natural complexes in the southern outskirts of the Ural Mountainous Country