Dalhousie Hardyhead, Craterocephalus dalhousiensis Ivantsoff & Glover 1974


Dalhousie Hardyhead, Craterocephalus dalhousiensis. Source: Rudie H. Kuiter/Aquatic Photographics. License: All rights reserved

Summary:
A golden-brown hardyhead with a darker brown back, a dark mid-lateral stripe and two to three rows of brown spots below the mid-lateral line. Males have an almost horizontal head profile and an arched abdomen. Females have the head sloping sharply towards the snout, and a flat abdomen.

Video of Dalhousie Hardyheads in Dalhousie Springs, Witjira National Park.

Cite this page as:
Bray, D.J. & Thompson, V.J. 2022, Craterocephalus dalhousiensis in Fishes of Australia, accessed 30 Sep 2022, https://fishesofaustralia.net.au/home/species/1375

Dalhousie Hardyhead, Craterocephalus dalhousiensis Ivantsoff & Glover 1974

More Info


Distribution

Endemic to the Dalhousie Mound Springs complex in the Witjira National Park in remote South Australia, in the Lake Eyre Basin. The species currently inhabits only five of the 148 mound springs.
Inhabits shady areas in pools and outflow channels of moderate to large springs, preferring areas where water temperatures remains above 20ºC. Individuals can tolerate water temperatures between 20-39°C, even darting out to briefly feed in waters up to 41.8°C.

Features

Dorsal fin IV-VI + I, 5-7; Anal fin I, 7-9; Pectoral fin 13-15; Gill rakers 7-8 (lower arch); Vertical scale rows 29-31; Horizontal scale rows 6-8. 

Body compressed somewhat elongate and deep; greatest body depth 3.7-4.7 in SL; lips thick and fleshy; skin of upper jaw fusing with skin over lower jaw about half way along the premaxilla; rear edge of jaw does not reach eye; large lower jaw; both jaws with many rows of small but visible curved teeth; dorsal surface in males almost horizontal from the snout to the origin of the first dorsal while abdomen is arched; females with a flat abdomen and head sloping sharply towards the snout with the interorbital space being flat to concave, depending on maturity.

Two short-based, well separated dorsal fins; caudal fin moderately forked; pectoral fins positioned high on sides, near top of gill openings, elongate and pointed; pelvic fins abdominal, elongate, pointed.

Size

To 8cm SL

Colour

Golden-brown overall, darker brown dorsally with a dark mid-lateral stripe and two to three rows of brown spots below the mid-lateral line.

Feeding

Feed mainly on green filamentous algae, detritus and small aquatic invertebrates.

Biology

Pair spawners with females depositing adhesive eggs amongst aquatic vegetation.  Hatching occurs within 5-7 days.

Conservation

IUCN Red List of Threatened Species: Critically Endangered.
The species is known only from Dalhousie Springs, where there is a continuing decline in habitat quality and the number of separate springs in which it occurs.

Remarks

The Dalhousie Hardyhead is the only Craterocephalus species known to be sexually dimorphic. 

Similar Species

Similar in colouration to C. stercusmuscarum, particularly in juvenile specimens. Adults differ from C. stercusmuscarum in having only one row of spots above the midlateral band, are deeper bodied and differ in counts of midlateral scales, vertebrae and gill rakers.

Etymology

The species is named for the type locality Dalhousie Springs in South Australia.

Species Citation

Craterocephalus dalhousiensis Ivantsoff & Glover 1974, Aust. Zool. 18(2): 88 fig. 1. Type locality: Dalhousie Springs, Main Spring, South Australia, 26°25' S, 135°30' E.

Author

Bray, D.J. & Thompson, V.J. 2022

Resources

Atlas of Living Australia

Dalhousie Hardyhead, Craterocephalus dalhousiensis Ivantsoff & Glover 1974

References


Allen, G.R. 1989. Freshwater Fishes of Australia. Neptune, New Jersey : T.F.H. Publications 240 pp.

Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field guide to the freshwater fishes of Australia.  Perth : Western Australian Museum 394 pp.

Crowley, L.E.L.M. & Ivantsoff, W. 1989. An historical overview of the genus Craterocephalus with special reference to the hardyheads from Dalhousie Springs. pp. 113-121 in Zeidler, W. &  Ponder, W.F. (eds). Natural History of Dalhousie Springs. Adelaide, South Australia : South Australian Museum.

Crowley, L.E.L.M. & Ivantsoff, W. 1990. A second hardyhead, Craterocephalus gloveri (Pisces: Atherinidae), from Dalhousie Springs, central Australia. Ichthyological Exploration of Freshwaters 1: 113-122.

Glover, C.J.M. 1989. Fishes. pp 89-112 in Zeidler, W. &  Ponder, W.F. (eds). Natural History of Dalhousie Springs. Adelaide, South Australia : South Australian Museum.

Hammer, M.P., Adams, M. & Foster, R.  2012. Update to the catalogue of South Australian freshwater fishes (Petromyzontida & Actinopterygii). Zootaxa 3593: 59-74.

Ivantsoff, W. & Glove,r C.J.M. 1974. Craterocephalus dalhousiensis n. sp., a sexually dimorphic freshwater teleost (Atherinidae) from South Australia. Australian Zoologist 18(2): 88-98 See ref at BHL

Merrick, J.R. & Schmida, G.E. 1984. Australian Freshwater Fishes Biology and Management.  Sydney : J.R. Merrick 409 pp

Wager, R. & Unmack, P.J. 2000. Fishes of the Lake Eyre Catchment of Central Australia. Brisbane : Department of Primary Industries and Queensland Fisheries Service 88 pp.

Whiterod, N., Hammer, M., Unmack, P., Mathwin, R. & Gotch, T. 2019. Craterocephalus dalhousiensis. The IUCN Red List of Threatened Species 2019: e.T5489A123377703. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T5489A123377703.en. Accessed on 03 August 2022.

Quick Facts


CAAB Code:37246018

Conservation:IUCN Critically Endangered

Habitat:Freshwater springs

Max Size:8 cm SL

Native:Endemic

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