Ophisternon candidum

(Mees 1962) Rosen and Greenwood 1976

Ophisternon candidum
Ophisternon candidum. Photograph from Moore (2018) with permission


Anomatophasma candidum  Mees 1962

Placed in the genus Ophisternon by Rosen and Greenwood (1976)




Holotype ("Type" in Mees, 1962): WAM P4917-001 356mm TL. Paratype WAM P4918-001 314mm TL. This species is the type species by original designation and monotypy of the genus Anomatophasma.


Type locality: Tantabiddi Well, near Yardie Creek Station, North West Cape, Western Australia (21o56’S, 113o58’E). Details of all other known locations are given in Moore et al (2018) and in the Table below. At nine locations this species has been seen at sites from which Milyeringa veritas has also been recorded. EPA (2012), Halse et al. (2014), Moore et al. (2018) and White et al. (2020) report an extension of the range to eastern Pilbara (see also Humphreys and Adams 1991, Adams and Humphreys 1993, Humphreys 1993 Knott 1993). White et al. (2020) used environmental DNA (eDNA) in boreholes in the eastern part of the range in Pilbara to search for locations containing O. candidum. They found that it was still present in bores BC186, JW023 and JW024 (as reported by Moore et al. (2018)), but also in three further bores: 25, RR1 and MB17MEH0015 and, suprisingly, in two surface water bodies. Ophisternon candidum is now know from three geographically isolated areas: Cape Range (East and West), Barrow Island and Pilbara.

Area Site No. Site name Species Latitude and longitude References
CRW C-26 Tantabiddi Well Oc

21o56’S, 113o58’E

CRW C-24 Milyering Well Oc, Mv 22o01’S, 113o56’E Mees (1962), Humphreys (1994), (1999)
CRE C-228 Ned's Well Oc 21o53’S, 114o06’E  
CRE C-23 Dozer Cave Oc, Mv 21o58’S, 114o08’E

Humphreys (1994), Humphreys and Adams (1991)

CRW C-274 Pilgramunna Well Oc, Mv 22o12’S, 113o52’E

Humphreys (1994)

CRE C-27 Kubura Well cave Oc, Mv 21o56’S, 114o08’E Humphreys and Adams (1991)
CRW None Just south of Yardie Creek Oc 22o21’S, 113o48’E

Allen (1992)

CRE C-361 Mowbowra Well Oc, Mv 22o00’S, 114o07’E Humphreys and Adams (1991)
CRW C-25 Kudumurra Well Oc, Mv 21o55’S, 113o59’E

Humphreys (1994)

CRW C-414 Wobiri Rock Hole Oc, Mv 21o50’S, 114o05’E

Humphreys (1994)

CRE C-495 New Mowbowra Well Oc, Mv 22o00’S, 114o07’E

Humphreys (1994)

CRW None Tidal Cave Oc 21o50’S, 114o06’E

Humphreys (1999)

Pilbara None Exploration bore BC186-155 Oc 21o49’S, 116o19’E Moore (2018), Moore et al. (2018)
Pilbara None Borehole JW023 Oc 21o47’S, 116o17’E Moore (2018), Moore et al. (2018)
Pilbara None Borehole JW024 Oc 21o47’S, 116o18’E Moore (2018), Moore et al. (2018)
Barrow Island None Anode Well T2 Oc 20o46’S, 115o25’E Moore (2018), Moore et al. (2018)
Barrow Island None Anode Well L15 Oc 20o48’S, 115o23’E Moore (2018), Moore et al. (2018)
Barrow Islamd None Seismic site E1918 Oc 20o41'S, 115o27'E Moore (2018), Moore et al. (2018)
CRW C-215 Unnamed Oc, Mv 22o2'S 113056' E Moore (2018), Moore et al. (2018)
Pilbara 25 Unnamed Oc Not given White et al. (2020)
Pilbara RR1 Unnamed Oc Not given White et al. (2020)
Pilbara MB17MEH0015 Unnamed Oc Not given White et al. (2020)
Pilbara Surface water Unnamed Oc Not given White et al. (2020)
Pilbara Surface water Unnamed Oc Not given White et al. (2020)

The distribution of Ophisternon candidum. Oc Ophisternon candidum, Mv Milyeringa veritas

Various stygobitic Crustacea are found in Cape Range, eastern Pilbara and Barrow Island and their biogeography can help to inform us about the distribution and ages of the fish taxa there. The following sources are useful in this regard:

Humphreys (1993) Stygofauna and a Tethyan connection

Yager and Humphreys (1996) Lasionectes exleyi (Crustacea: Remipedia)

Page et al. (2008) Stygiocaris (Decapoda: Atyidae)

Humphreys (2017) Australasian subterranean biogeography - covers all groups in the groundwaters

Page et al. (2018) Halosbaena (Peracarida: Thermosbaenacea)

Matthews et al. (2019) Parabathnellidae diversity in Pilbara


Details of Kubura Well are provided by Cawthorn (1963). Potential food supply for the fishes is provided by both stygobitic crustaceans  (including representatives of the Thermosbaenacea, Atyidea, and Remipedia) and terrestrial insects and Crustacea. Humphreys and Feinberg (1995) made a detailed examination of the gut contents of some specimens. The fish is carnivorous and eats both other cave fauna (Thermosbenacea, Halosbaena tuski and Atyidae, Stygiocaris sp.) and terrestrial Isopoda, Odonata and Diptera. They clearly obtain food both at the water surface and within the cave. Eberhard et al. (2005) provide details of the other stygobitic fauna of the Pilbara region, which will provide much of the food supply for the fishes, and the stygobitic fauna of Barrow Island is provided by Humphreys et al. (2013). The Cape Range karst is the 4th most biodiverse subterranean habitat in Australia with 83 obligate subterranean species (41 terrestrial and 42 aquatic). The Barrow Island Karst is the 5th most diverse with 74 obligate species (18 terrestrial and 56 aquatic) (Ebergard and Haworth 2021).


Moore (2018) and Moore et al. (2018) report that O. candidum has recently been found in the east of the Pilbara region. This means that O. candidum is now known from the east and west of Cape Range, eastern Pilbara and Barrow Island. Milyeringa is also found in east and west Cape Range and Barrow Island but as two separate species, M veritas (CR) and M. justitia (BI), [it is not yet known from eastern Pilbara]. Given this evolutionary split within Milyeringa Morgan et al. (2014) suggest that the Ophisternon taxon on Barrow Island might be a seperate endemic species. However, Moore et al. (2018) showed conclusively, using both morphological and molecular evidence, that all at three areas have the same species.

Much recent work by W.F. Humphreys and others has shed some light on the evolution of the Cape Range troglobites. The area appears to be Tethyan and all but one of its stygofauna is of Tethyan origin.

Conservation Status


(Wager, R. 1996. Ophisternon candidum. The IUCN Red List of Threatened Species 1996: Downloaded on 06 July 2017).I (IUCN 1988, 1990), K (IUCN 1993). Michaelis (1985) classes this species as vulnerable. The Cape Range area is arid and a centre for developments. The water needs of the human population are such that “the water table is declining and becoming more saline" (Humphreys and Adams 1991). The most recent sightings of this animal are in an area where building development is planned.

The conservation of karst sites, and their fauna, in western Autralia is considered in a very detailed report by the Environmental Protection Authority (2012).

Museum Holdings

As above plus: AMNH 32404 259mm TL  (Rosen and Greenwood 1976:51), WAM P5813-001 309mm TL, WAM P7716-001 268mm SL (Humphreys and Feinberg 1995), WAM P33136-001 183mm TL, WAM P34329-001 298mm SL, WAM P34487-001 90mm TL, WAM P34487-001 364mm SL, WAM P34615-001 63mm TL, WAM P34657 385mm TL, WAM P34817-001 60mm TL  (Moore 2018, Moore et al. 2018).

Internet Resources

Australian Government conservation assessment

Ningaloo Coast world heritage nimination with details of the subterranean fauna

Mitochondrial genome (White et al. 2020, Tian et al. 2021)

Mitochondrial CYTB (1) (Moore et al. 2018)

Mitochondrial CYTB (2) (Moore et al. 2018)

Mitochondrial CYTB (3) (Moore et al. 2018)

Mitochondrial CYTB (4) (Moore et al. 2018)

Mitochondrial CYTB (5) (Moore et al. 2018)

Mitochondrial CYTB (6) (Moore et al. 2018)

Mitochondrial COI (1) (Moore et al. 2018)

Mitochondrial COI (2) (Moore et al. 2018)

Mitochondrial COI (3) (Moore et al. 2018)

Mitochondrial COI (4) (Moore et al. 2018)

Mitochondrial COI (5) (Moore et al. 2018)

Mitochondrial COI (6) (Moore et al. 2018)

Key References

Mees, G.F. Journal Article 1962 The subterranean freshwater fauna of Yardie Creek Station, North West Cape, Western Australia
Cawthorn, P. Journal Article 1963 Discovery of subterranean freshwater fauna on the eastern side of North West Cape
Richards, A. M. Journal Article 1963 The subterranean freshwater fauna of North West Cape, Western Australia
Rosen, D. E. and Greenwood, P. H. Journal Article 1976 A fourth neotropical species of synbranchid eel and the phylogeny and systematics of synbranchiform fishes
Michaelis, F. Journal Article 1985 Threatened fish. A report on the threatened fish of inland waters of Austalia
Pollard, D. A., Ingram, B. A., Harris, J. H. and Reynolds, L. F. Journal Article 1990 Threatened fishes in Australia - an overview
Humphreys, W. F. and Adams, M. Journal Article 1991 The subterranean aquatic fauna of the North West Cape peninsula, Western Australia
Allen, G.R. Book 1992 Inland Fishes of Western Australia
Humphreys, W. F. Journal Article 1993 The significance of the subterranean fauna in biogeographical reconstruction: Examples from Cape Range Peninsula, Western Australia
Adams, M. and Humphreys, W.F. Journal Article 1993 Patterns of genetic diversity within selected subterranean fauna of the Cape Range penninsula, Western Australia: Systematic and biogeographic implications
Knott, B. Journal Article 1993 Stygofauna of the Cape Range penninsula, Western Australia: Tethyan relicts
Humphreys, W. F. Book 1993 The biogeography of Cape Range, Western Australia
Humphreys, W.F. Journal Article 1994 The subterranean fauna of the Cape Range coastal plane, Northwestern Australia
Humphreys, W. F. and Feinberg, M. N. Journal Article 1995 Food of the blind cave fishes of Northwestern Australia
Yager, J. and Humphreys, W. F. Journal Article 1996 Lasionectes exleyi sp. nov. the first Remipede crustacean recorded from Australia and the Indian Ocean, with a key to the world species
Eberhard, S. and Hamilton-Smith, E. Journal Article 1996 Conservation of cave fauna in Australia
Hamilton-Smith, E., Kiernan, K. and Spate, A. Journal Article 1996 Karst management considerations for the Cape Range karst province, Western Australia
Humphreys, W.F. Book Section 1997 Protection of arid karstlands on the Cape Range Penninsula, Western Australia
Humphreys, W. F. Journal Article 1999 Physico-chemical profile and energy fixation in Bundera Sinkhole, an anchialine remiped habitat in north-western Australia
Humphreys, W. F. Journal Article 1999 The distribution of Australian cave fishes
Humphreys, W.F., Poole, A., Eberhard, S.M. and Warren, D. Journal Article 1999 Effects of research diving on the physico-chemical profile of Bundera Sinkhole, an anchialine remiped habitat at Cape Range, Western Australia
Romero, A. and Vanselow, P.B.S. Journal Article 2000 Threatened fishes of the world: Ophisternon candidum (Mees, 1962) Synbranchidae
Romero, A. and Vanselow, P.B.S. Journal Article 2000 Threatened fishes of the world: Milyeringa veritas Whitley, 1945 (Eleotridae)
Humphreys, W.F. Book Section 2000 The hypogean fauna of the Cape Range Peninsula and Barrow Island, northwestern Australia
Humphreys, W.R. Journal Article 2001 Groundwater calcrete aquifers in the Australian arid zone: the context to an unfolding plethora of stygal biodiversity
Humphreys, W.F. Journal Article 2001 Milyeringa veritas (Eleotridae), a remarkably versatile cave fish from the arid tropics of northwestern Australia
Wilson, R.S. and Humphreys, W.F. Journal Article 2001 Prionospio thalajani sp. nov. (Polychaeta: Spionidae) from an anchialine cave, Cape range, north-western Australia
Humphreys, WF Journal Article 2001 The subterranean fauna of Barrow island, northwestern Australia, and its environment
Jaume, D., Boxshall, G.A. and Humphreys, W.F. Journal Article 2001 New stygobiont copepods (Calanoida; Misophrioida) from Bundera sinkhole, an anchialine cenote on north-western Australia
Moore, B.P., Humphreys, W.F., Decu, V. and Juberthie, C. Book Section 2001 Australie
Unmack, P.J. Journal Article 2001 Biogeography of Australian freshwater fishes
Boulton, A.J., Humphreys, W,F. and Eberhard, S.M. Journal Article 2003 Imperilled subsurface waters in Ausralia: biodiversity, threatening processes and conservation
Hancock, P.J., Boulton, A.J. and Humphreys, W.F. Journal Article 2005 Aquifers and hyporheic zones: Towards an ecological understanding of groundwater.
Eberhard, S.M., Halse, S.A. and Humphreys, W.F. Journal Article 2005 Stygofauna in the Pilbara region, north-west Western Australia: a review
Humphreys, W.F. Journal Article 2006 Aquifers: the ultimate groundwater-dependent ecosystems
Humphreys, W.F., Shiao, J.-C., Iizuka, Y. and Tzeng, W.-N. Journal Article 2006 Can otolith microchemistry reveal whether the blind cave gudgeon, Milyeringa veritas (Eleotridae), is diadromous within a subterranean estuary?
Furter, E. Journal Article 2007 Underground life : environmental assessments just became more complicated
Finston, T.L., Johnson, M.S., Humphreys, W.F., Eberhard, S.M. and Halse, S.A. Journal Article 2007 Cryptic speciation in two widespread subterranean amphipod genera reflects historical drainage patterns in an ancient landscape
Humphreys, W.F. Journal Article 2008 Rising from down under: developments in subterranean biodiversity in Australia from a groundwater fauna perspective
Humphreys, W.F., Watts, C.H.S., Cooper, S.J.B. and Leijs, R. Journal Article 2009 Groundwater estuaries of salt lakes: buried pools of endemic biodiversity on the western plateau, Australia
Collins, L.B. and Stevens, A. Report 2010 Assessment of coastal groundwater and linkages with Ningaloo Reef – final report February 2010
Department of the Environment, Water, Heritage and the Arts Report 2010 Ningaloo Coast World Heritage nomination
Environmental Protection Authority Report 2012 A review of subterranean fauna assessment in Western Australia. Discussion Paper. February 2012
Humphreys, W., Tetu, S., Elbourne, L., Gillings, M., Seymour, J., Mitchell, J. and Paulsen, I. Journal Article 2012 Geochemical and microbial diversity of Bundera Sinkhole, an anchialine system in the eastern Indian Ocean
Humphreys, W.F Book Section 2012 Diversity patterns in Australia
Abrams, K. M., Guzik, M.T., Cooper, S.J.B., Humphreys, W.F., King, R.A., Cho J.L. and Austin, A.D. Journal Article 2012 What lies beneath: molecular phylogenetics and ancestral state reconstruction of the ancient subterranean Australian Parabathynellidae (Syncarida, Crustacea)
Humphreys, G., Alexander, J., Harvey, M.S. and Humphreys, W.F. Journal Article 2013 The subterranean fauna of Barrow Island, northwestern Australia: 10 years on
Unmack, P.J. Journal Article 2013 Biogeography
Larson, H.K., Foster, R., Humphreys, W.F. and Stevens, M. Journal Article 2013 A new species of blind cave gudgeon Milyeringa (Pisces: Gobioidei, Eleotridaee) from Barrow Island, Western Australia, with a redescription of M. veritas Whitley
Morgan, D.L., Unmack, P.J., Beatty, S.J., Ebner, B.C., Allen, M.G., Keleher, J., Donaldson, J.A. and Murphy, J. Journal Article 2014 An overview of the 'freshwater fishes' of Western Australia
Halse, S., Scanlon, M., Cocking, J., Barron, H., Richardson, J. and Eberhard, S. Journal Article 2014 Pilbara stygofauna: deep groundwater of an arid landscape contains globally significant radiation of biodiversity
Bishop, R.E., Humphreys, W.F., Cukrov, N., Zic, V., Boxshall, G.A., Cukrov, M., Iliffe, T.M., Krsinic, F., Moore, W.S., Pohlman, J.W., and Sket, B. Journal Article 2015 ‘Anchialine’ redefined as a subterranean estuary in a crevicular or cavernous geological setting
Humphreys, W. F. Book Section 2017 Australasian subterranean biodiversity
Moore, G.I. Journal Article 2018 New morphological data and live photographs of the rare subterranean blind cave eel Ophisternon candidum (Synbranchidae) from north‑western Australia
Moore, G.I., Humphreys, W.F. and Foster, R. Journal Article 2018 New populations of the rare subterranean Blind Cave Eel Ophisternon candidum (Synbranchidae) reveal recent historical connections throughout northwestern Australia
Page, T.J., Hughes, J.M., Real, K.M., Stevens, M.I., King, R.A. and Humphreys, W.F. Journal Article 2018 Allegory of a cave crustacean: systematic and biogeographic reality of Halosbaena (Peracarida: Thermosbaenacea) sought with molecular data at multiple scales
Halse, S. Book Section 2018 Subterranean fauna of the arid zone
Page, T.J.,Stevens, M.I., Adams, M., Foster, R. Velasco-Castrillón, A. and Humphreys, W.F. Journal Article 2018 Multiple molecular markers reinforce the systematic framework of unique Australian cave fishes (Milyeringa : Gobioidei)
Perina, G., Camacho, A.I., Huey, J., Horwitz, P., and Koenders, A. Journal Article 2018 Understanding subterranean variability: the first genus of Bathynellidae (Bathynellacea, Crustacea) from Western Australia described through a morphological and multigene approach
Perina, G., Camacho, A.I., Huey, J., Horwitz, P. and Koenders, A. Journal Article 2019 New Bathynellidae (Crustacea) taxa and their relationships in the Fortescue catchment aquifers of the Pilbara region, Western Australia, Systematics and Biodiversity
Perina, G., Camacho, A., Huey, J., Horwitz, P. and Koenders, A. Journal Article 2019 The role of allopatric speciation and ancient origins of Bathynellidae (Crustacea) in the Pilbara (Western Australia): two new genera from the De Grey River catchment
Matthews, E.F., Abrams, K.M., Cooper, S.J.B., Huey, J.A., Hillyer, M.J., Humphreys, W.F., Austin, A.D. and Guzik, M.T. Journal Article 2019 Scratching the surface of subterranean biodiversity: molecular analysis reveals a diverse and previously unknown fauna of Parabathynellidae (Crustacea: Bathynellacea) from the Pilbara, Western Australia
Perina, G. Thesis 2019 Ancient origins of a diverse stygofaunal group: The Australian Bathynellidae (Crustacea)
Shelley, J.J., Swearer, S.E., Dempster, T., Adams, M., Le Feuvre, M.C., Hammer, M.P. and Unmack, P.J. Journal Article 2020 Plio-Pleistocene sea-level changes drive speciation of freshwater fishes in north-western Australia
Lintermans, M., Geyle, H.M., Beatty, S., Brown, C., Ebner, B.C., Freeman, R., Hammer, M.P., Humphreys, W.F., Kennard, M.J., Kern, P., Martin, K., Morgan, D.L., Raadik, T.A., Unmack, P.J., Wager, R., Woinarski, J.C.Z. and Garnett, S.T. Journal Article 2020 Big trouble for little fish: identifying Australian freshwater fishes in imminent risk of extinction
White, N.E., Guzik, M.T., Austin, A.D., Moore, G.I. Humphreys, W.F., Alexander, J. and Bunce, M. Journal Article 2020 Detection of rare Australian endemic blind cave eel (Ophisternon candidum) with environmental DNA: implications for threatened species management in subterranean environments
Eberhard, S.M. and Howarth, F.G. Journal Article 2021 Undara lava cave fauna in tropical Queensland with an annotated list of Australian subterranean biodiversity hotspots
Tian, H., Hu, Q., Lu, H. and Li, Z. Journal Article 2021 The complete mitochondrial genome of one breeding strain of Asian swamp eel (Monopterus albus, Zuiew 1793) using PacBio and Illumina sequencing technologies and phylogenetic analysis in synbranchiformes
Saccò, M., Blyth, A.J., Douglas, G., Humphreys, W.F., Hose, G.C., Davis, J., Guzik, M.T., Martínez, A., Eberhard, S.M. and Halse, S.A. Journal Article 2022 Stygofaunal diversity and ecological sustainability of coastal groundwater ecosystems in a changing climate: The Australian paradigm
Saccò, M., Guzik, M.T., van der Heyde, M., Nevill, P., Cooper, S.J.B., Austin, A.D., Coates, P.J. and Allentoft, M.E. Journal Article 2022 eDNA in subterranean ecosystems: Applications, technical aspects, and future prospects
van der Heyde, M., Alexander, J., Nevill, P., Austin, A.D., Stevens, N., Jones, M. and Guzik, M.T. Journal Article 2023 Rapid detection of subterranean fauna from passive sampling of groundwater eDNA
Webb, J.A., White, S.Q. and Smith, G.K. Book 2023 Australian caves and karst systems
White, S.Q., Brooks, D. and Webb, J.A. Book Section 2023 Cape Range
van der Heyde, M., White, N.E., Nevill, P., Austin, A.D., Stevens, N., Jones, M. and Guzik, M.T. Journal Article 2023 Taking eDNA underground: factors affecting eDNA detection of subterranean fauna in groundwater