Conservation status of the only representative of infraorder Mygalomorphae (Araneae) in cultivated regions of Central Europe

Abstract

Purse-web spiders Atypus spp. (Araneae: Atypidae) are the only representatives of the archaic spider infraorder Mygalomorphae in the Central European fauna. These burrow-dwelling spiders are red-listed in all Central European countries. Atypus muralis occurs on relics of continental steppes, Atypus piceus on dry submediterranean grassland and dry herb-rich forest fringes, while Atypus affinis inhabits sparse dwarf dry forests, usually those dominated by oaks. Long-term sustainability of their habitats in the relatively humid Central European climate was maintained by grazing. Since the 1950s, pasturing was terminated across most of Central Europe, which led to immediate overgrowth of pastures by aggressive grasses and woody plants. Grazing was later reinstated in some reserves, but in cases of poorly controlled grazing intensity, footsteps had immediate detrimental effects on the residual populations of purse-web spiders and other invertebrates. Therefore, grazing intensity needs to be regulated, considering its double-edge effects on the biota of xerothermophilic habitats. Nests of European Atypus species have never been found in habitats subject to recent or even regular distribution. Therefore, they may serve as reliable indicators of well preserved xerothermic habitats. Their nests are easy to detect, and the European Atypus spiders can be utilized as model species for monitoring impacts of conservation management. Monitoring population dynamics of Atypus requires establishing permanent study plots of uniform size, documentation of vegetation by phytocenological releve, counting their density (number of purse-webs found in the plot) and age structure (diameter of purse webs).