Dillie Grunter, Syncomistes dilliensis Shelley, Delaval & Le Feuvre 2017


Summary:
A relatively small mostly black to sometimes bluish grunter with no horizontal stripes on the body. Juveniles are overall olive green to somewhat bluish in colour.
The Dilie Grunter has a relatively pronounced long notch behind the upper lip, a concave dorsal profile between the notch and the dorsal-fin origin, and a squat V-shaped jaw that is wider than long.

Cite this page as:
Bray, D.J. 2020, Syncomistes dilliensis in Fishes of Australia, accessed 06 Feb 2023, https://fishesofaustralia.net.au/home/species/5401

Dillie Grunter, Syncomistes dilliensis Shelley, Delaval & Le Feuvre 2017

More Info


Distribution

Endemic to the Isdell, Charnley, and Calder Rivers in The Kimberley region, Western Australia. Adults prefer fast flowing sections of creeks and rivers, although they often occur in deep, slow flowing pools. Inhabits clear waters over rocky substrates, often where algae is abundant. Juveniles occur mostly in riffle habitats.
The Dillie Grunter is moderately abundant within the Charnley and Calder River systems, while in the Isdell River this species is rare. 

Features

Dorsal fin XI-XII, 11-12; Anal fin III, 8-9; Pectoral fin 14-15; Caudal fin 9-12 + 8-9 + 7+ 9-12; Gill rakers 8-10 + 17-20 =  26-29; Vertebrae 11+14=25; Lateral line scales 48-53; Scale rows between lateral line and dorsal-fin 10-14; Scale rows between lateral line and pectoral-fin origin 18-23; Dorsal sheath scale rows 2; Caudal peduncle scales 33-37.
Differs from all other species of Syncomistes in having the following combination of characters: lower jaw distinctly pointed when viewed from below, making a ‘V-shape’ in individuals > 65 mm; mouth subterminal; teeth flattened, narrow and short, ‘peg-shaped’ with anterior and posterior edges running straight and parallel from tooth base, tapering slightly at apical region to a rounded point; jaw of adults (> 65 mm) as wide as it is long or slightly longer when viewed from below; dorsal profile straight from dorsal origin to shallow notch on upper jaw; body lacking stripes; ventral profile only slightly convex; head slightly rounded from juveniles through to adults; jaw relatively short usually < 30.0 in HL; 9–11 anal fin rays (usually 10); 17–19 gill rakers on lower arch (usually 18); postorbital length relatively short, usually < 40.0 % HL.

Size

A relatively small species of Syncomistes (recorded up to 132 mm SL, commonly 70–100 mm SL).

Colour

Juveniles (<65 mm) olive-green to blue overall, darker dorsally, becoming lighter towards ventral surface. Scales above lateral line dark with gold posterior margins, below lateral line light with dark posterior margins; lateral-line scales black; olive-green iridescent tinge along lateral line and on operculum; olive green to blue tinged stripe running below eye to snout, and a dark spot present on upper edge of gill cover; head and body below lateral line with black speckling; single black stripe sometimes running straight from upper opercular spine to middle of caudal peduncle. Membranes of spinous dorsal dusky for basal three-quarters, black at the tips; membranes of softdorsal fin dusky, interrupted by a black stripe running length of fin, close to base, fin margin white; membranes of spinous and soft anal fin light white with large dark blotch on middle of rays; pelvic fins white with black pigmentation along membrane between middle 8 rays; pectoral fins clear; caudal fin dusky, lighter at fin edge.  
Adults overall black in appearance, lighter on ventral surface; scales iridescent olive green to gold, sometimes light black with thick black margins; iridescent olive-green tinge on operculum; horizontal olive-green tinged stripe running below eye to snout. Membranes of spinous dorsal fin uniformly black; membranes of soft dorsal fin black with a slight white margin along fin edge; membranes of spinous and soft anal fin black with slight white margin along fin edge; pelvic fins black with slight white margin along fin edge; pectoral fins clear; caudal fin black, slight white margin along fin edge. No stripes along sides of adults.

Feeding

Diet primarily consists of filamentous algae and detritus scraped off rocks with specially modified teeth.

Biology

Nothing is known about the reproductive biology of this species. 

Similar Species

Broadly similar morphological grouping to Syncomistes versicolor, S. dilliensis, and S. rastellus based on the presence of a more pronounced, longer notch behind the upper lip, a more pronounced concave dorsal profile between the notch and the dorsal fin, and a squat V-shaped jaw that is wider than it is long. Unique in appearance although, most closely resembles S. rastellus. S. dilliensis can be distinguished from by having, on average, fewer dorsal-fin spines 11–12,and greater counts of the following characters: lateral line scales 48–53, scale rows between the lateral line and dorsal 10–14 and pectoral origin 18–23, dorsal sheath scale rows 2, caudal peduncle scales 33–37, and teeth on the lower jaw (relative to jaw length). Differences in morphology include shorter jaw width 26.3–32.6% HL and smaller fin measurements including: dorsal base length 48.5–53.2% SL, dorsal fin length 51.8–58.3% SL, dorsal spine length 10.3–13.5 % SL, anal spine length 11.2–15.1% SL, pectoral fin length 17.8–21.2% SL, and pelvic spine length 7.8–10.6% SL. Body colour is variable, although overall colour ranges from olive green / blue in juveniles to black in adults, rather than silver in juveniles and adults (S. holsworthi), gold in juveniles to black in adults (S. dilliensis), or olive green to light brown in juveniles and adults (S. rastellus).

Etymology

The specific name dilliensis refers to the type locality, Dillie Gorge, on the Charnley River, Western Australia.

Species Citation

Syncomistes dilliensis Shelley, Delaval & Le Feuvre 2017, Zootaxa 4367(1): 42, Fig. 14. Type locality: Charnley River at Pearson Creek confluence with Charnley River, 16° 12' 39.63'' S, 125° 30' 17.53'' E.

Author

Bray, D.J. 2020

Resources

Atlas of Living Australia

Dillie Grunter, Syncomistes dilliensis Shelley, Delaval & Le Feuvre 2017

References


Le Feuvre, M. C. 2017. Triple jeopardy in the tropics: assessing extinction risk in Australia's freshwater biodiversity hotspot. Ph.D. Thesis, School of Biosciences, University of Melbourne. http://hdl.handle.net/11343/194371

Le Feuvre, M.C. 2019. Syncomistes dilliensis. The IUCN Red List of Threatened Species 2019: e.T129056539A129056543. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T129056539A129056543.en. Downloaded on 31 August 2020.

Shelley, J.J. 2016. Evolution and biogeography of Australian tropical freshwater fishes. PhD Thesis. The University of Melbourne, Melbourne, VIC, 273 pp. http://hdl.handle.net/11343/120615 (as Syncomistes sp. 3)

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 http://dx.doi.org/10.11646/zootaxa.4367.1.1

Shelley, J.J., Gomon, M.F. & Le Feuvre, M.C. 2018. Family Terapontidae. pp. 118-158 in Shelley, J.J., Morgan, D.L., Hammer, M.P., Le Feuvre, M.C., Moore, G.I., Gomon, M.F., Allen, M.G. & Saunders, T. (eds) A field guide to the freshwater fishes of the Kimberley. Murdoch University, Murdoch, Western Australia, 262 pp. 

Quick Facts


CAAB Code:37321038

Conservation:IUCN Vulnerable

Habitat:Freshwater

Max Size:13.2 cm SL

Native:Endemic

Species Maps

CAAB distribution map