A new stygobiotic species of the genus Proasellus (Crustacea: Isopoda: Asellidae) from South Dagestan, Russia

. A new species of the stygobiotic pond slater, Proasellus precaspicus sp.n. (Crustacea: Isopoda), was described from groundwater of the Samur River in the Samursky National Park (Southern Dagestan, Russia). This is the first finding of the genus from the territory of the East Caucasus and Caspian Sea coast. The new species is morphologically close to other species known for the Caucasus region, especially to those described from North Ossetia. However, it can be easily recognized due to the combination of the following characters: inner margin of dactylus of pereopodes I with five to nine robust stiff setae; inner margin of dactylus of pereopodes II–VII with single robust stiff spiniform seta; inferior margin of propodus of pereopodes I with three long robust stiff setae; pleopod I with single coupling hook in retinacula of pleopod I. The new species inhabits various springs in the sources of small rivers and streams, as well as hyporheic waters.