Drysdale Grunter, Syncomistes rastellus Vari & Hutchins 1978


Drysdale Grunter, Syncomistes rastellus. Source: Gerald R. Allen / Western Australian Museum. License: All rights reserved

Summary:
A small grunter known only from north-western Australia. The Drysdale Grunter is blackish to greenish-grey with paler scale centres, and blotch on the anal fin of some individuals. Juveniles have a longitudinal stripe running from the upper gill cover to the tail base.

Cite this page as:
Gomon, M.F. & Bray, D.J. 2017, Syncomistes rastellus in Fishes of Australia, accessed 22 Aug 2018, http://fishesofaustralia.net.au/Home/species/2524

Drysdale Grunter, Syncomistes rastellus Vari & Hutchins 1978

More Info


Distribution

Endemic to the Kimberley region, and known only from the Gibb River (126º30´E) and Drysdale River (127º00´E), and one record from Ord River system near Lake Argyle, WA.

Prefers large freshwater rivers rather than small tributaries, particularly in areas of flowing water. It inhabits clear to murky waters over a variety of bottom types.

Features

Dorsal fin XII-XIII, 10-12; Anal fin III, 7-9; Pectoral fin 13-16; Pelvic fin I, 5; Lateral line scales 45-49; Vertebrae 11+14; Gill rakers 8-11 + 1 + 19-21.

Body moderately deep, increasingly so with age, 2.7-3.35 in SL, ovate; dorsal and ventral profiles almost evenly arched. Head length 3.30-3.60 in SL. Snout distinctly pointed in adults, length 2.25-2.90 in HL. Nostrils separated by distance equal to one and one-half times diameter of posterior nostril, both nostrils with free cutaneous edges, anterior tube-like. Eye width 3.70-5.20 in HL. Interorbital region smooth. Maxillary reaching to vertical through posterior nostril; upper jaw slightly more fleshy and longer than lower, length 2.70-3.80 in HL; lower jaw triangular when viewed from ventral aspect, reduced, flattened, with teeth pointing laterally; upper jaw with a greater number of teeth than lower; outer row of teeth brown tipped and of irregular heights, followed internally by narrow band of smaller similarly shaped teeth; lower jaw with prominent dorsally projecting median symphyseal bump; bump corresponding in shape to and inserting into groove between premaxillaries; both bump and depression endentulous; no teeth on vomer or palatines. Lacrimal (first infraorbital) with 3-4 coarse serrations. Preoperculum weakly serrate, more so along vertical edge. Lower opercular spine longer and stronger, not extending beyond edge of opercular lobe. Cleithrum exposed, weakly serrate in some individuals; with scales on side. Supracleithrum exposed. Posttemporal exposed; serrate along posterior edge.
Scales finely ctenoid; lateral line continuous, smoothly curved; transverse scales 6-7/1/14-16; three to six caudal scales; 10 to 15 pre-dorsal scales to occiput; cheek scales in three rows; sheath at base of spinous dorsal fin consisting of one or two irregular rows, sheath extending to fifth to seventh dorsal-fin rays; sheath at base of anal fin consisting of three to five rows of scales, sheath extending to fourth anal-fin ray.Dorsal fin continuous, base 1.80-1.95 in SL; spinous portion low, arched, first spine short; fifth to seventh spines longest, 1.70-2.60 in HL, those following decreasing gradually in length to penultimate which is slightly shorter than last; longest dorsal- fin ray 1.75-2.60 in HL; soft dorsal fin with a straight posterior border. Second anal-fin spine longest, 1.33-2.20 in HL, twice length of first; stronger and slightly longer than third; longest anal-fin ray 1.50-2.00 in HL; soft anal fin angular, with straight or slightly concave border. Pelvic fins pointed; first ray longest, reaching two-thirds distance to anus in juveniles, one-half distance in adults. Pectoral fins asymmetrically pointed, fifth ray longest. Caudal fin emarginate.

Size

To around 15 cm SL.

Colour

Head, body, and fins blackish grey to greenish grey with paler scale centres; anal fin of some with a basal blotch. Juveniles with a longitudinal stripe running from supracleithrum to caudal fin base.

Feeding

Herbivore - uses specially modified teeth and jaws to graze on filamentous algae growing on rocks.

Biology

Little is known of the reproductive biology of this species but it is likely to breed during October to December.

Conservation

  • IUCN Red List : Near Threatened
  • Remarks

    Sometimes forms mixed species shoals with S. trigonicus.

    Etymology

    The generic name, Syncomistes, a masculine Greek noun meaning gatherer, refers to the algae-cropping habits of the members of this genus. The specific name rastellus, from the Greek for rake, refers to the rake-like dentition of the species.

    Species Citation

    Syncomistes rastellus Vari & Hutchins, 1978,  Am. Mus. Novit. 2654: 1–4. Type locality: North Creek, tributary of Gibb River, Western Australia.

    Author

    Gomon, M.F. & Bray, D.J. 2017

    Drysdale Grunter, Syncomistes rastellus Vari & Hutchins 1978

    References


    Allen, G.R. (1982). Inland Fishes of Western Australia.  Perth : Western Australian Museum 86 pp. 6 figs 20 pls [51].

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

    Allen, G.R. & Leggett, R. 1990. A collection of freshwater fishes from the Kimberley region of Western Australia. Records of the Western Australian Museum 14(4): 527-545 fig. 1

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

    Morgan, D.L., Allen, G.R., Pusey, B.J. & Burrows, D.W. 2011. A review of the freshwater fishes of the Kimberley region of Western Australia. Zootaxa 2816: 1-64.

    Shelley, J.J., Delaval, A. & Le Feuvre, M.C. 2017. A revision of the grunter genus Syncomistes (Teleostei, Terapontidae, Syncomistes) with descriptions of seven new species from the Kimberley region, northwestern Australia. Zootaxa 4367(1): 1-103 DOI: http://dx.doi.org/10.11646/zootaxa.4367.1.1  Abstract

    Unmack, P.J. 2001. Biogeography of Australian freshwater fishes. Journal of Biogeography 28: 1053-1089.

    Vari, R.P. & Hutchins, J B. (1978). New species of terapon perches (Percoidei, Terapontidae) from Australia. Am. Mus. Novit. 2654: 1–8 figs 1–9.

    Wager, R. 1996. Syncomistes rastellus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. . Downloaded on 2 June 2012.

    Quick Facts


    CAAB Code:37321030

    Conservation:IUCN Near Threatened

    Habitat:large freshwater rivers

    Max Size:15 cm SL

    Native:Endemic

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