Proteus anguinus

Laurenti 1768



see below  

There are numerous synonyms, see the Amphibians of the World webpage for a full list

Common name is Olm, or The Olm


Dinaric Karst


This species is stygobitic (i.e. aquatic)


The genus Proteus Laurenti 1768 is widely distributed on the eastern side of the Adriatic Sea and populations are currently found in Italy, Slovenia, Croatia, Bosnia Herzegovina and probably also in Montenegro (Kostanjsek et al. 2023). Currently there is only one nominal species in the genus, Proteus anguinus Laurenti 1768 with two subspecies: P. anguinus anguinus Laurenti 1768 and P. anguinus parkelj  Sket and Arntzen 1994. The first of these subspecies in troglomorphic whereas the second is pigmented and known as the “black Proteus” or “black morph”. Populations are found over a linear northwest to southeast distance of 500km and it has been hypothesized several times that these are not all the same species. There is now clear genetic evidence that there are at least nine evolutionary significant units (ESUs) across this distribution and in due course it is highly likely that all of these nine will eventually be described as separate species with their own species names. Currently (see Kostanjsek et al. 2023 and Recknagel et al. 2023 for details) there are nine named ESUs:

Ljubljanica (containing the type locailty of P. anguinus which will eventually be the only species to bear this name)




Proteus anguinus parkelj





Making 9 probable species in the genus. This will mean that there are currently 25 global species of subterranean Amphibia (16 in North and Central America and 9 in Europe).

Conservation Status

VU B2ab(ii, iii, v)

Internet Resources

Amphibians of the World


Key References

In order to save time and resources all bibliographic details for the nine Proteus species are provided under the species account for Proteus anguinus. These references are all entirely relevant to all nine known species but nothing is gained by repeating them nine times

Valvasor J.W. Book 1689 Die Ehre des Herzogthums Crain.
Laurenti J.L. Book 1768 Specimen Medicum, Exhibens Synopin Reptilium Emendatam cum Experimentis circa Venena et Antidota Reptilium Austriacorum.
Hochenwart, F. Journal Article 1838 Protheus anguinus
Fitzinger, L. Journal Article 1850 Ueber den Proteus anguinus der Autoren
Fejervary, G.J. Journal Article 1926 Note sur la variation du Protee et description d'individus provenants d'un nouvel habitat
Briegleb, W. Journal Article 1962 Zur Biologie und Oekologie des Grottenolms (Proteus anguinus Laur. 1768
Durand, J.P. Journal Article 1972 Recherches sur l'appareil visuel du protee, Proteus anguinus Laurenti, urodele hypoge
Thines, G. and Durand, J. Journal Article 1973 Connaissances actuelles sur l'appareil sensoriel da la ligne laterale chez les vertebres cavernicoles aquatique
Durand, J.P. Journal Article 1973 Development et involution oculaire de Proteus anguinus Laurenti Urodele cavernicole
Durand, J.P. Journal Article 1976 Rudimentation des yeux chez les poissons et urodeles souterraines
Sket, B. and Velkovrh, F. Journal Article 1978 The discovery of Proteus-eggs (Proteus anguinus Laurenti, Amphibia) in seminatural conditions
Garasic, M. Conference Paper 1980 Pronadjena covjecja ribica (Proteus anguinus) u podzemnoj rijeci Rokine bezdane kod Jezerana u Lici
Kranjec, N. Thesis 1981 Razsirjenost in variabilnost mocerila (Proteus anguinus Laurenti)
Durand, J.P. and Delay, B. Journal Article 1981 Influence of temperature on the development of Proteus anguinus (Caudata: Proteidae) and relation with its habitat in the subterranean world
Durand, J.P. Journal Article 1982 Donnees et hypotheses sur l'evolution des Proteidae
Aljančič, M., Habič, P. and Mihevc, A. Journal Article 1986 Črni močeril iz Bele krajine [The Black olm from White Carniola]
Bulog, B. Journal Article 1989 Differentiation of the inner ear sensory epithelia of Proteus anguinus (Urodela, Amphibia)
Aljančič, M., Bulog, B., Kranjc, A., Josipovič, D., Sket, B. and Skoberne, P. Book 1993 Proteus – The Mysterious Ruler of Karst Darkness
Sket, B. Book Section 1994 "Yugoslavia" (Bosnia-Herzegovina, Croatia, Macedonia, Montenegro, Serbia, Slovenia)
Sket, B. and Arntzen, J.W. Journal Article 1994 A black, non-troglomorphic amphibian from the karst of Slovenia: Proteus anguinus parkelj n. ssp. (Urodela: Proteidae)
Grillitsch, H. and Tiedemann, F. Journal Article 1994 Die Grottenolm-Typen Leopold Fitzingers (Caudata: Proteidae: Proteus)
Kletecki, E., Jalzic, B. and Rada, T. Journal Article 1996 Distribution of the Olm (Proteus anguinus, Laur.) in Croatia
Sket, B. Journal Article 1997 Distribution of Proteus (Amphibia: Urodela: Proteidae) and its possible explanation
Durand, J.P. Book Section 1998 Amphibia
Tvrtkovic, N. Journal Article 1999 Cavernicole vertebrates of the Dinaric karst
Weber, A. Book Section 2000 Fish and amphibia
Kos, M., Bulog, B., Szél, Á. and Röhlich, P. Journal Article 2001 Immunocytochemical demonstration of visual pigments in the degenerate retinal and pineal photoreceptors of the blind cave salamander (Proteus anguinus).
Kletecki, E., Jalzic, B. and Rada, T. Book Section 2002 Amphibia
Sket, B., Paragamian, K. and Trontelj, P. Book Section 2004 A census of the obligate subterranean fauna of the Balkan peninsula
Sket, B. Book Section 2004 Dinaric Karst: Biospeleology
Bulog, B. Book Section 2004 Amphibia: Proteus
Weber, A. Book Section 2004 Amphibia
Durand, J.P. Book Section 2005 Salamanders
Sket, B. Book Section 2005 Dinaric Karst, Diversity in
Gorički, Š. and Trontelj, P. Journal Article 2006 Structure and evolution of the mitochondrial control region and flanking sequences in the European cave salamander Proteus anguinus
Trontelj, P., Gorički, Š., Polak, S., Verovnik, R., Zakšek, V. and Sket, B. Journal Article 2007 Age estimates for some subterranean taxa and lineages in the Dinaric Karst
Schlegel, P.A., Steinfartz, S. and Bulog, B. Journal Article 2009 Non-visual sensory physiology and magnetic orientation in the blind cave salamander, Proteus anguinus (and other cave-dwelling urodele species): review and new results on light-sensitivity and non-visual orientation in subterranean urodeles (Amphibia)
Pezdirc, M., Heath, E., Mali, L.B. and Bulog, B. Journal Article 2011 PCB accumulation and tissue distribution in cave salamander (Proteus anguinus anguinus, Amphibia, Urodela) in the polluted karstic hinterland of the Krupa River, Slovenia
Goricki, S., Niemiller, M.L. and Fenolio, D.B. Book Section 2012 Salamanders
Hajna, N.Z. Book Section 2012 Dinaric Karst: Geography and geology
Sket, B. Book Section 2012 Diversity patterns in the Dinaric karst
Ivanović, A., Aljančič, G. and Arntzen, J.W. Journal Article 2013 Skull shape differentiation of black and white olms (Proteus anguinus anguinus and Proteus a. parkelj): An exploratory analysis with micro-CT scanning
Sessions, S., Bulog, B. and Mali, L.B. Journal Article 2015 The phoenix rises: Reversal of cave adaptations in the blind cave salamander, Proteus anguinus?
Bizjak Mali. L. and Bulog, B. Journal Article 2016 Functional morphology and environmental studies on Proteus
Bonacci, O. Book 2017 Karst Hydrology : With Special Reference to the Dinaric Karst
Gorički, S., Stanković, D., Snoj, A., Kuntner, M., Jeffery, W.R., Trontelj, P., Pavićević, M., Grizelj, Z., Năpăruş-Aljančič, M. and Aljančič, G. Journal Article 2017 Environmental DNA in subterranean biology: range extension and taxonomic implications for Proteus
Vörös, J., Márton, O., Schmidt, B.R., Gál, J.T., & Jelić, D. Journal Article 2017 Surveying Europe's only cave-dwelling chordate species (Proteus anguinus) using environmental DNA.
Bizjak-Mali, L. Journal Article 2017 Variability of testes morphology and the presence of testis-ova in the European blind cave salamander (Proteus anguinus)
Năpăruș-Aljančič, M., Gorički, Š., Stanković, D., Kuntner, M. and Aljančič, G. Journal Article 2017 GIS analysis to assess the groundwater habitat pollution of black proteus
Vörös, J., Ursenbacher, S. and Jelić, D. Journal Article 2018 Population genetic analyses using 10 new polymorphic microsatellite loci confirms genetic subdivision within the olm, Proteus anguinus
Zakšek, V., Konec, M. and Trontelj, P. Journal Article 2018 First microsatellite data on Proteus anguinus reveal weak genetic structure between the caves of Postojna and Planina
Kostanjšek, R., Prodan, Y., Stres, B. and Trontelj, P. Journal Article 2019 Composition of the cutaneous bacterial community of a cave amphibian, Proteus anguinus
Gorički, Š., Niemiller, M.L., Fenolio, D.B. and Gluesenkamp, AG. Book Section 2019 Salamanders
Aljančič, G. Journal Article 2019 History of research on Proteus anguinus Laurenti 1768 in Slovenia
Balázs, G., Lewarne, B. and Herczeg, G. Journal Article 2020 Extreme site fidelity of the olm (Proteus anguinus) revealed by a long-term capture–mark–recapture study
Li. Z., Verbrugghe, E., Konstanjšek, R., Lukač, M., Pasmans, .F, Cizelj., I. and Martel, A. Journal Article 2020 Dampened virulence and limited proliferation of Batrachochytrium salamandrivorans during subclinical infection of the troglobiont olm (Proteus anguinus)
Gredar, T. Thesis 2020 Development of non-destructive approaches for sex identification in the Proteus (Proteus anguinus, Urodela, Amphibia)
Whittaker, K. and Koo, M.S. Web Page 2021 Proteus anguinus: Olm
Garasic, M. Book 2021 The Dinaric Karst System of Croatia. Speleology and Cave Exploration
Tesarová, M., Mancini, L., Mauri, E., Aljancic, G., Naparus-Aljancic, M., Kostanjšek, R., Mali, L.B., Zikmund, T., Kaucká, M., Papi, F., Goyens, J., Bouchnita, A., Hellander, A. Journal Article 2022 Living in darkness: Exploring adaptation of Proteus anguinus in 3 dimensions by X-ray imaging
Kostanjšek, R. et al. Journal Article 2022 Towards the massive genome of Proteus anguinus, illuminating longevity, regeneration, convergent evolution and metabolic disorders
Guillaume, O. Conference Paper 2022 The cave salamander Proteus anguinus in captivity in Moulis, France for the scientific research
Barzaghi, B., Ficetola, F.G., Mauri, E., Restaino, M., Lombardi, B. and Manenti, R. Conference Paper 2022 Preliminary study on differences characterizes the populations of olm (Proteus anguinus) in cave and those found in epigean environment
Recknagel, H., Zakšek, V., Delić, T., Gorički, S. and Trontelj, P. Journal Article 2023 Multiple transitions between realms shape relict lineages of Proteus cave salamanders
Kostanjsek, R., Zaksek, V., Bizjak-Mali, L. and Trontelj, P. Book Section 2023 Chapter 13. The olm (Proteus anguinus), a flagship groundwater species
Lewarne, B. and Allain, S.J.R. Journal Article 2023 Attempted predation of a cave olm Proteus anguinus by a dice water snake Natrix tessellata, in Bosnia and Herzegovina
Barzaghi, B. Thesis 2023 Between light and darkness: The round-trip of surface and subterranean animals