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.).
Habitat and Ecology
The species generally occurs in large subterranean aquatic karst systems formed in limestone and dolomite rocks, and may be found in cave entrances (especially during episodes of high rainfall and flooding) and abandoned mine workings. Many of the caves that the species occurs in are connected to rivers that run above ground for the first 50-100km and then disappear into the ground. Populations may be found close to the surface or as much as 300m underground depending on the thickness of the Karstic formation. The species is found in waters ranging from 5°C to 15°C. Animals feed on detritus and endemic cave invertebrates and hide in crevices or bottom sediment when disturbed. In contrast to the nominate subspecies, P. a. parkelj is found in warmer surface waters. The species is long-lived (they are not sexually mature until they are 12 years of age) and reproduce very slowly. Females lay approximately 70 individual eggs on the undersides of aquatic stones; however, in some cases the eggs are retained within the body and two fully formed young are produced.
There is little information available on the abundance of this species, but it is apparently most common in Slovenia and Croatia. A decline has been observed in the populations of Goriza (Italy) and Postojna (Slovenia) (Gasc et al. 1997). The number of individuals of the subspecies P. a. parkelj is very low.
The main threats to this species are changes to the forested and pastoral land above the subterranean systems, largely through tourism, economic changes, and increasing water pollution. These changes have a direct influence on the quality of the habitat available to the species. The species is highly dependent on clean water, and is therefore very susceptible to pollution. Other localized threats to this species might include water abstraction and hydroelectric schemes. There is some illegal collection of this species for the pet trade, but the extent of this is unknown.
It is listed on Appendix II of the Bern Convention, and on Annexes II* and IV of the EU Habitats Directive. It is recorded in the Slovenian National Red List and is protected by national legislation in many range states, e.g. Slovenia, Croatia and Italy. In Slovenia the species is present in caves, which are protected by national legislation, and much of the distribution of this species is within proposed national or international protected areas (Kocevski and Kraski regional parks; NATURA 2000 sites). In Italy it is found in the Riserva Naturale Regionale dei Laghi di Doberdò e Pietrarossa. The subspecies P. a. parkelj is in need of protection, as its habitat is limited to only a few holes in connection with subterranean networks in a very small geographic area.
Red List Status
Listed as Vulnerable because its Area of Occupancy is less than 2,000 km2, its distribution is severely fragmented, and there is continuing decline in the extent and quality of its habitat, and presumably also in the number of mature individuals.
Most populations are assigned to the subterranean subspecies Proteus anguinus anguinus. Unlike the nominate form, the genetically similar subspecies P.a. parkelj from Bela Krajina in Slovenia is pigmented and might represent a distinct species, although a recent genetic study suggests that the two subspecies are poorly differentiated at the molecular level and may not even warrant subspecies status (Goricki and Trontelt 2006).
Jan Willem Arntzen, Mathieu Denoël, Claude Miaud, Franco Andreone, Milan Vogrin, Paul Edgar, Jelka Crnobrnja Isailovic, Rastko Ajtic, Claudia Corti 2009. Proteus anguinus. The IUCN Red List of Threatened Species 2009: e.T18377A8173419. http://dx.doi.org/10.2305/IUCN.UK.2009.RLTS.T18377A8173419.en