Abstract
BACKGROUND: Ecosystems in protected areas are richer in animal and plant species diversity ("biodiversity hotspots") due to more stringent conservation conditions. Of particular importance is scientific research and monitoring of this diversity in such areas. The aim of this study is to describe a set of data on Araneae occurrence in two protected areas: Mordovia State Nature Reserve and National Park "Smolny". NEW INFORMATION: About 29,000 individuals are identified to the species level. In total, 342 species were recorded for both PAs. The greatest species diversity was recorded in the families Linyphiidae (109 species; 32%), Lycosidae (38 species; 11%) Gnaphosidae (28 species; 8%), Araneidae (25 species; 7%), Salticidae (24 species; 7%), Thomisidae (23 species; 7%) and Theridiidae (22 species; 6% from total species diversity). The five species most abundant in the lower stratum (litter and moss layer) of biocenoses were Diplocephaluspicinus, Micronetaviaria, Tenuiphantestenebricola, Diplostylaconcolor and Abacoproecessaltuum and the five species most abundant in the vegetative stratum (herb, shrub and tree stems and canopy) were Linyphiatriangularis, Enoplognathaovata, Evarchafalcata, Misumenavatia and Evarchaarcuata. The dataset contains information on the occurrence of seven rare species (Centromerusnurgush, Centromeruspersimilis, Diplocephalusdentatus, Entelecaraflavipes, Metapanamomopskaestneri, Pelecopsisradicicola and Porrhommamicrocavense), three species (Agalenatearedii, Neosconaadianta, Thanatusoblongiusculus) that entered here from the steppe zone and two synanthropic species (Steatodacastanea, Tegenariadomestica).