Blind Gudgeons

Western Australia has either two or three blind cave gudgeons: Milyeringa brooksi from Cape Range (Chakrabarty 2010), M. justitia from Barrow Island (Larson et al. 2013) and M. veritas also from Cape Range (Humphreys 2001). Larson et al. (2013) reported the allozyme analysis of Humphreys and Adams (1991) and Adams and Humphreys (1993) of the two potential Cape Range ‘species’ were consistent with a single species, so they suggested that M. veritas and M. brooksi are synonymous, and the oldest name stands, indicating there are only two species: M. veritas and M. justitia.

Milyeringa veritas and M. justitia are listed as Schedule 3 species (Fauna that are rare or are likely to become extinct as vulnerable fauna) but only M. veritas is listed as a threatened (i.e. vulnerable) species under the EPBC Act 1999.

Milyeringa veritas is restricted to the subterranean waters on either side of the Cape Range peninsula in the northwestern Australia. It lives in freshwater caves and in seawater in anchialine systems. It has mostly been caught or seen in the inland karst systems up to 4.3km from the coast. The anchialine ecosystems are fresh to brackish water overlying seawater that is not directly connected to the seas but is influenced by marine tides (Humphreys 2001). Humphreys (2001) reported M. veritas in a range of water chemistries, often with complex physico-chemical stratification (e.g. 0.3g L-1 TDS to 34 g l-1 TDS) and from hyperoxic surface water to suboxic waters below the pycnocline, as well as foraging in sediments and covered with black and white sulphur bacteria. Much less is known of M. justitia, as only six individuals have been collected since 2002 (Humphreys et al. 2013). It is presumed that its diet and ecology are similar to M. veritas.

As their name suggests, Blind gudgeons are eyeless, with little pigment and are almost translucent, with reduced scales on the body and few or none on the head; all characteristic of a troglobitic existence. In keeping with these external characteristics they are slow moving. They are often seen hanging in the water column motionless or lying on rock ledges. Milyeringa veritas displays similar behaviour in an aquarium, but when threatened with capture they can quickly move away to avoid being caught in a net.

Humphreys and Feinberg (1995) reported that the diet of M. veritas included stygofauna (Stygiocaris sp.), aquatic larvae of terrestrial species (e.g. caddis larvae) and terrestrial species that were accidentally in the water (e.g. isopods, ants and cockroaches) in its diet. Even though it is a cave dwelling creature only 10% of its identifiable gut contents were stygofauna and 70% were terrestrial species.

Western Australia is lucky to be endowed with a diverse and rich endemic fauna, with many species largely unknown to the general public. Greater engagement of the community in the management of threatened species could result in larger government funding allocations to threatened species management and larger amounts of wildlife philanthropy.

References

Adams, M., and W. F. Humphreys. 1993. Patterns of genetic diversity within selected subterranean fauna of the Cape Range peninsula, Western Australia: systematic and biogeographic implications. Records of the Western Australian Museum:145-164.

Chakrabarty, P. 2010. Status and phylogeny of Milyeringidae (Teleostei: Gobiiformes), with the description of a new blind cave-fish from Australia, Milyeringa brooksi, n. sp. Zootaxa 2557:19-28.

Humphreys, G., J. Alexander, M. S. Harvey, and W. F. Humphreys. 2013. The subterranean fauna of Barrow Island, north-western Australia: 10 years on. Records of the Western Australian Museum Supplement 83:145-158.

Humphreys, W. F. 2001. Milyeringa veritas (Eleotridaae), a remarkable vertsatile cave fish from the arid tropics of northwestern Australia. Environmental Biology of Fishes 62:297-313.

Humphreys, W. F., and M. Adams. 1991. The subterranean aquatic fauna of the North West Cape peninsula, Western Australia. Records of the Western Australian Museum 15:383-411.

Humphreys, W. F., and M. N. Feinberg. 1995. Food of the blind cave fishes of the northwestern Australia. Records of the Western Australian Museum 17:29-33.

Larson, H. K., R. Foster, W. F. Humphreys, and M. I. Stevens. 2013. A new species of the blind cave gudgeon Milyeringa (Pisces: Gobioidei, Eleotridae) from Barrow Island, Western Australia, with a redescription of M. veritas Whitley. Zootaxa 3616:135-150.

Photo credit: Blind Gudgeon  (Supplied by Gunther Schmida)