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.
The Dalhousie Hardyhead is found only in the warm waters of the Dalhousie Springs, Witjira National Park, South Australia. This is the only Craterocephalus species known to be sexually dimorphic. Males have an almost horizontal profile between the snout and the first dorsal fin 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. 2017, Craterocephalus dalhousiensis in Fishes of Australia, accessed 17 Nov 2018, http://fishesofaustralia.net.au/home/species/1375

Dalhousie Hardyhead, Craterocephalus dalhousiensis Ivantsoff & Glover 1974

More Info


Distribution

Endemic to Dalhousie Springs in Witjira National Park, South Australia, in the Lake Eyre basin. Dalhousie Hardyheads inhabit shady areas in the tropical warm freshwater artesian streams and outlet flows. They are able to tolerate water temperatures between 20-39°C. Individuals have been recorded briefly feeding in waters where the temperature reached 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

Diurnally active feeding primarily on green filamentous algae, detritus and small bottom-dwelling invertebrates.

Biology

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

Conservation

Listed as vulnerable on the IUCN red list of threatened species
Not listed under the Australian EPBC Act.

Remarks

Occurs in 7 of the approximately 35 artesian springs that make up the Dalhousie Springs.

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

Genus name Craterocephalus comes from the Greek meaning bowl or basin and head, possibly in reference to the strong head of species in this genus. Species name is derived from the type locality, Dalhousie Springs, which includes about thirty-three artesian springs of varying size and activity, scattered over an area of nearly 75 km.

Species Citation

Craterocephalus dalhousiensis Ivantsoff, W. & Glover, C.J.M. (1974). Craterocephalus dalhousiensis n. sp., a sexually dimorphic freshwater teleost (Atherinidae) from South Australia. Aust. Zool. 18(2): 88–98 figs 1–3 [88 fig. 1]. Dalhousie Springs, SA.

Author

Bray, D.J. & Thompson, V.J. 2017

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.

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

Ivantsoff W. & Glover C.J.M. (1974) Craterocephalus dalhousiensis n. sp., a sexually dimorphic freshwater teleost (Atherinidae) from South Australia. Aust. Zool. 18(2): 88-98

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

Wager, R. (1996). Craterocephalus dalhousiensis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2. www.iucnredlist.org

Wager, R. & Unmack, P.J. (2000). Fishes of the Lake eyre catchment of central Australia.  Department of Primary Industries Queensland Fisheries Service 88 pp.

Quick Facts


CAAB Code:37246018

Conservation:IUCN Vulnerable

Habitat:Freshwater springs

Max Size:8 cm SL

Native:Endemic

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