Leathery Grunter, Scortum hillii (Castelnau 1878)


Other Names: Green-hide Jack, Hill's Grunter, Leatherjacket Grunter

Leathery Grunter, Scortum hillii. Source: Jill Ruse. License: all rights reserved

Summary:
Body golden-brown or olive to bluish-green above, paler below, with irregular spots of varying sizes scattered on the body. Juveniles are paler, often with a mottled pattern above. 

Cite this page as:
Martin F. Gomon, Scortum hillii in Fishes of Australia, accessed 14 Nov 2018, http://fishesofaustralia.net.au/home/species/702

Leathery Grunter, Scortum hillii (Castelnau 1878)

More Info


Distribution

Known only from from the Fitzroy River system, QLD; a tropical species inhabiting flowing freshwater streams and still pools in clear or turbid water with temperatures between 12 and 35ºC; also occurs in estuaries.

Features

Meristic features: Dorsal fin XIII, 11-13; Anal fin III, 8-10; Pectoral fin 15-17; Pelvic fin I, 5; Lateral line 50-62; Transverse scales 11-13/1/22-28; Gill rakers 8-13+1+16-26; Vertbrae 11+14.

Body moderately deep, 2.5-3.0 in SL, ovate, slightly compressed, more so in adults; dorsal profile much more pronounced than ventral in juveniles, only slightly more in adults, nearly straight from snout in interorbital region, concave above eyes, then convex to dorsal origin; dorsal profile of adults straighter overall; ventral profile straight from lower jaw to anus in young, gently curved in adults; more pronounced in larger specimens. Head length 3.05-3.5 in SL. Snout blunt, more so in adults. Nostrils separated by a distance equal to diameter of posterior nostril. Eye width 3.5-5.7 in HL. Jaws equal, length 3.4-4.5 in HL; gape oblique; maxillary reaching to vertical through posterior nostril or anterior of eye; teeth partially flattened, depressible; in bands with outer row enlarged; teeth variably present on vomers in adults, lacking on palatines. Lacrimal serrate; strongly in young; serrations obscure or lacking in larger individuals. Preoperculum serrate; serrations stronger on angle and vertical edge; becoming weaker with age. Lower opercular spine stronger and longer; not extending beyond edge of opercular lobe. Posttemporal exposed; posterior edge serrate. Cleithrum exposed; posterior edge serrate; serrations weaker with age; scales on side. Supracleithrum exposed.

Scales relatively small, finely ctenoid; lateral line continuous, smoothly curved; 3-5 scales on caudal; 14-18 predorsal scales to occiput; 2 rows of scales in sheath at base of dorsal fin, sheath extending to fourth or fifth dorsal ray; 3-4 rows of scales in sheath at base of anal fin, sheath extending to seventh to tenth anal ray; cheek scales in 5-6 rows; 63-71 scales in a series above lateral line; 11-13 scales below the lateral line.

Dorsal fin continuous, base 1.6-1.8 in SL; spinous portion arched; first spine short; fifth or sixth longest, 1.7-2.4 in HL, those following decreasing gradually to the penultimate, which is slightly shorter than ultimate, longest dorsal spines longer than longest dorsal rays, longest dorsal ray 2.1-2.5 in HL; soft dorsal rounded. Second anal spine twice as long as first spine, 1.8-2.2 in HL, much longer than third in juveniles, less so in adults where they may be of the same length; longest anal ray 1.6-2.1 in HL, soft anal rounded in young, more angular in adults. Pectoral fins asymmetrically pointed; fourth or fifth rays longest. Ventral fins pointed; first ray longest, slightly filamentous; reaching three-quarters of distance to anus. Caudal fin emarginate.

Size

To 35 cm SL, commonly to 25 cm.

Colour

Body olive or grayish on back and sides, with irregular spots of varying size and position on sides; much paler overall in juveniles. Head darker above, pale below, without any prominent markings. Spinous portion of dorsal fin uniformly dusky; paler in young; soft dorsal dusky with paler edge and dark basal blotch. Caudal fin uniformly dusky, darker in adults. Pectoral fins dusky; more heavily pigmented at base. Pelvic fins dusky.

Feeding

Omnivore - feeds mostly on mussels and algae.

Biology

Oviparous, migrating upstream to spawn during summer when water levels rise.

Etymology

The species is named hillii in honour of Mr. Hill, former director of the Brisbane Botanical Gardens.

Species Citation

Therapon hilli Castelnau, 1878, Proc. Linn. Soc. N.S.W. (1)2(3): 226. Type locality: Dawson River, Taroom, QLD.

Author

Martin F. Gomon

Leathery Grunter, Scortum hillii (Castelnau 1878)

References


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

Castelnau, F.L. de (1878). Australian fishes, new or little known species. Proc. Linn. Soc. N.S.W. (1)2(3): 225–248 pls 1–2

Grant, E.M. (1975). Guide to Fishes.  Brisbane : Co-ordinator-General Department 3rd Edn  640 pp. (as Therapon hillii).

Grant, E.M. (2002). Guide to Fishes.  Redcliffe : E.M. Grant Pty. Limited 9th Edn  880 pp.

Vari, R.P. (1978). The terapon perches (Percoidei, Terapontidae) a cladistic analysis and taxonomic revision. Bull. Amer. Mus. Nat. Hist. 159(5): 175–340 figs 1–94.

Wager, R. 1996. Scortum hillii. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. <www.iucnredlist.org>. Downloaded on 25 September 2013

Quick Facts


CAAB Code:37321026

Conservation:IUCN Data Deficient

Habitat:Freshwater rivers and estuaries

Max Size:35 cm SL

Native:Endemic

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