Bald Carp Gudgeon, Hypseleotris gymnocephala Thacker, Geiger & Unmack 2022

Other Names: Lake's Carp Gudgeon
A pale carp gudgeon often with 6-7 alternating darker patches along the body, clear to dusky fins, and a blunt head. Breeding males have a noticeable hump of the forehead, and a pale orange sub-marginal band shading into a narrow white margin on the outer part of the dorsal and anal fins.
The species also lacks dorsal scales on the head and anterior part of the body as far back as the middle of the second dorsal fin. 

Cite this page as:
Bray, D.J. 2022, Hypseleotris gymnocephala in Fishes of Australia, accessed 28 Sep 2022,

Bald Carp Gudgeon, Hypseleotris gymnocephala Thacker, Geiger & Unmack 2022

More Info


Restricted to two small creeks in the upper Lachlan River in the Murray Darling Basin.


Dorsal fin VII-VIII; I,10-12 (rarely 10); Anal fin I,11-12; Pectoral fin 15-17 (rarely 17); Lateral scales 28-35. Scales absent from head; no head pores. Urogenital papillae in males and females blunt, with lateral edges of papilla longer than incised centre, yielding w-shaped outline.


Hemiclonal lineages involving this species and Hypseleotris bucephala are widespread across the Murray-Darling Basin (MDB), the Bulloo River (BBB) and Cooper Creek (LEB). Hemiclones with H. acropinna are known from the MDB. Some hemiclones have also been recorded from coastal drainages south of the Mary River, including the Brisbane, Clarence and Georges rivers, all within the range of H. galii.

Similar Species

Differs from other southeastern Australian species of Hypseleotris in having a blunt head with dorsal scales absent as far back as the middle of the second dorsal fin. The species also lacks the pointed dorsal and anal fin tips that are found in H. acropinna, H. galii and H. mooloboolaensis, and the unique median fin coloration in mature males - outer part of fin bearing band of pale orange, shading into thin band of white.

Like H. bucephala, H. gymnocephala has a blunter snout than other Hypseleotris species, and breeding males of both species also develop an expanded hump on the forehead.


The specific name gymnocephalus is from the Greek gymnos (= naked) and kephale (= head) in reference to the scaleless skin of the forehead, nape and dorsal midline anterior to the first dorsal fin characteristic of this species.

Species Citation

Hypseleotris gymnocephala Thacker, Geiger & Unmack 2022, Royal Society Open Science 9: 12, Fig. 7. Type locality: Meadow Creek, a Lachlan River tributary at Gunning, New South Wales, Australia (PU14-170), 34.7789 S, 149.2686 E.


Bray, D.J. 2022


Atlas of Living Australia

Bald Carp Gudgeon, Hypseleotris gymnocephala Thacker, Geiger & Unmack 2022


Allen, G.R. 1989. Freshwater Fishes of Australia. Neptune, New Jersey : T.F.H. Publications 240 pp., 63 pls. (as Hypseleotris sp. B)

Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field Guide to the Freshwater Fishes of Australia. Perth : Western Australian Museum 394 pp. (as Hypseleotris sp. 1, =hemiclones)

Hoese, D.F., Larson, H.K. & Llewellyn, L.C. 1980. Family Eleotridae: gudgeons.  pp. 169–185, 19 figs in McDowall, R.M. (ed.) Freshwater Fishes of South-eastern Australia.  Sydney : A.H. & A.W. Reed 208 pp. figs. (as Hypseleotris sp. 5, =hemiclones)

Larson, H.K. & Hoese, D.F. 1996. Family Gobiidae, subfamilies Eleotridinae and Butinae. pp. 200-219 in McDowall, R.M. (ed.) Freshwater Fishes of South-eastern Australia. Sydney : Reed Books 247 pp. (as Hypseleotris sp. 5, =hemiclones)

Thacker, C.E., Shelley, J.J., McCraney, W.T. et al. 2022. Phylogeny, diversification, and biogeography of a hemiclonal hybrid system of native Australian freshwater fishes (Gobiiformes: Gobioidei: Eleotridae: Hypseleotris). BMC Ecology and Evolution 22

Thacker, C.E. & Unmack, P.J. 2005. Phylogeny and biogeography of the eleotrid genus Hypseleotris (Teleostei: Gobioidei: Eleotridae), with redescription of H. cyprinoidesRecords of the Australian Museum 57: 1-13. (as Hypseleotris sp. 5, =hemiclones)

Thacker, C.E., Unmack, P.J., Matsui, L. & Rifenbark, N. 2007 Comparative phylogeography of five sympatric Hypseleotris species (Teleostei: Eleotridae) in south-eastern Australia reveals a complex pattern of drainage basin exchanges with little congruence across species. Journal of Biogeography 34: 1518–1533. 01711.x (as Hypseleotris sp. 5, =hemiclones)

Unmack, P.J., Adams, M., Bylemans, J., Hardy, C.M., Hammer, M.P. & Georges, A. 2019. Perspectives on the clonal persistence of presumed ‘ghost’ genomes in unisexual or allopolyploid taxa arising via hybridization. Scientific Reports 9: 4730

Unmack, P. & Pearce, L. 2019. Hypseleotris sp. nov. 'bald'. The IUCN Red List of Threatened Species 2019: e.T123321717A123382581. Accessed on 10 February 2022. 

Quick Facts

CAAB Code:37429050

Conservation:IUCN Critically Endangered



Species Maps

CAAB distribution map