The species is restricted to subterranean aquatic habitats within the Dinaric Alps, ranging from southern Slovenia and adjoining north-east Italy through coastal Croatia and karst regions of Bosnia and Herzegovina. It has yet to be officially recorded in western parts of Montenegro despite considerable anecdotal evidence of its presence (Kalezic and Dzukic, 2001). The species has been introduced to a cave of the subterranean laboratory of the CNRS France in the Pyrenees (C. Miaud pers. comm.), and one of the north-eastern Italian populations (in the Vicenza area) was introduced in the 1800s (P. Edgar pers. comm.).