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NATIVE SPECIES Common Name Dwarf flat-headed gudgeon Uncommon Photo: Gunther Schmida Scientific Name Philypnodon macrostomus Hoese & Reader 2006 Male in breeding colouration Identification A small, fish with a truncate to rounded tail. Maximum length 65 mm; rarely more than 40 mm. The head is broad and flat with a large mouth. Males have a larger mouth, extending beyond the rear margin of the eye, whereas in females it extends to below the middle of the eye. The gill openings on the underside of the head are narrow, extending forward to below the posterior portion of the gill covers, ending well behind the eye. It has two separate dorsal fins. The upper head and body is brown to black with irregular blotches, and a vertical black bar on the base of the caudal fin. Two black oblique bands extend backwards from the eye. The first dorsal fin has two black bands interspersed with orange or whitish areas. The second dorsal fin has 3–4 black stripes, also interspersed with orange or whitish areas. The caudal fin has orange spotting. This species can be easily confused with small individuals of Flat-headed gudgeon but can be distinguished by: the narrower gill openings which do not extend to, or below 98 the eye; the smaller number of pectoral fin rays (15–16); and the black bar at the base of the tail. This recently described species is variable in morphology across its range, with some Murray-Darling populations differing in body patterning and pre-dorsal scalation to the taxon described from coastal drainages near Coffs Harbour. Further taxonomic work is required. Dwarf flat-headed gudgeon has also been confused with Philypnodon grandiceps, and some references to P. grandiceps prior to 1980 probably refer to Dwarf flat-headed gudgeon. Biology and Habitat Dwarf flat-headed gudgeon reportedly prefer relatively calm waters and occur over mud and rock substrates or in weedy areas. However, recent information from coastal populations in southeastern Queensland indicates that this species occurs over coarser substrates such as gravel and cobbles, close to submerged cover such as leaf-litter accumulations, woody habitat and aquatic vegetation. Nothing is F i s h e s o f t h e M u r r ay- D a r l i n g B a s i n ID Valley 1 Avoca 2 Border Rivers 3 Broken 4Campaspe 5Castlereagh 6Central Murray 7Condamine 8Darling 9Goulburn 10Gwydir 11 Kiewa 12 Lachlan 13 Loddon 14 Lower Murray 15 Macquarie 16 Mitta Mitta 17 Murrumbidgee 18Namoi 19Ovens 20 Paroo 21Upper Murray 22 Warrego 23 Wimmera known of the reproductive biology in the wild, and little is known of its general ecology in the Basin. In aquaria it has been recorded breeding at temperatures of 19–22°C. The eggs are transparent and teardrop shaped, and hatch in 4–5 days. The male fish guards the egg mass, fanning them regularly and driving away other fish. The Dwarf flat-headed gudgeon is a benthic carnivore, feeding mainly on aquatic insects and their larvae such as chironomids, mayflies and caddisflies. Distribution and Abundance Dwarf flat-headed gudgeons are relatively common in coastal streams from southern Qld to Wilsons Promontory in Vic, and there are some outlying coastal populations near Adelaide in eastern SA. They occur also in the inland MDB but are patchily distributed and have only been recorded from a few localities. It is known from the Macquarie drainage near Bathurst, the Murrumbidgee near Canberra, the Boorowa River near Boorowa, the upper Murray near Albury, the Condamine near An introductory guide Condamine and Chinchilla, and the Lower Lakes and Mount Lofty Ranges in SA. It has also been reported from wetlands and edges of the lower Murray River up to Torrumbarry weir. In the first two sampling rounds of the Sustainable Rivers Audit covering 16 river valleys encompassing 351sampling sites, only 9 individuals were captured, all from the Lower Murray. The species has not been recorded from the ACT. Potential Threats None known. Predation (larval and adult) by alien fishes and interaction with the aggressive Eastern gambusia may be threats. General References Allen et al. 2002; Fletcher 1997; Hammer 2004; Higham et al. 2005; Hoese & Reader 2006; Koehn & O’Connor 1990; Larson & Hoese 1996a; Lintermans & Osborne 2002; Lloyd & Walker 1986; Merrick & Schmida 1984; Pusey et al. 2004; Wedderburn & Hammer 2003. 99 Published by the Murray-Darling Basin Commission Postal address: GPO Box 409, Canberra ACT 2601 Office location: Level 3, 51 Allara Street, Canberra City ACT Telephone: (02) 6279 0100, international + 61 2 6279 0100 Facsimile: (02) 6248 8053, international + 61 2 6248 8053 Email: [email protected] Internet: http://www.mdbc.gov.au For further information contact the Murray-Darling Basin Commission office on (02) 6279 0100 This fish fact sheet is an extract derived from the report: Lintermans, M. 2007, Fishes of the Murray-Darling Basin: An introductory guide. MDBC Publication No. 10/07 ISBN 1 921257 20 2 © Murray-Darling Basin Commission 2007 This work is copyright. Graphical and textual information in the work (with the exception of photographs, artwork and the MDBC logo) may be stored, retrieved and reproduced in whole or in part provided the information is not sold or used for commercial benefit and its source (Fishes of the Murray-Darling Basin) is acknowledged. Such reproduction includes fair dealing for the purpose of private study, research, criticism or review as permitted under the Copyright Act 1968. Reproduction for other purposes is prohibited without the permission of the MurrayDarling Basin Commission or the individual photographers and artists with whom copyright applies. To extent permitted by law, the copyright holders (including its employees and consultants) exclude all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this report (in part or whole) and any information or material contained in it. ii F i s h e s o f t h e M u r r ay- D a r l i n g B a s i n