Syncomistes versicolor, Shelley & Delaval & Le, 2017

Shelley, James J., Delaval, Aurélien & Le, Matthew 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), pp. 1-103 : 74-79

Syncomistes versicolor , new species

( Tables 27 , 28 , S 22 & S 23 ; Figures 26 & 27 )

Corresponds to the nominated taxa code ‘ Syncomistes sp. 2’ of Shelley (2016).

English vernacular name: The Many-coloured Grunter.

Holotype (measured): WAM P.34540.001 (145 mm SL), Lower Prince Regent , Prince Regent River, 15° 25' 1.68'' S, 125° 14' 13.28'' E, obtained with gill nets in a deep, clear pool over sandstone substrate by J. J. Shelley and M. C. Le Feuvre, July 24, 2013.

Paratypes (measured): eight specimens, 70.8–168 mm SL. WAM P.34540.002 (3), 94.3–168 mm SL, NTM S.18112-001 (1), 155 mm SL, Lower Prince Regent , Prince Regent River, 15° 25' 1.68'' S, 125° 14' 13.28'' E, caught alongside the holotype ; NMV A.31452-002 (1), 92.0 mm SL, NMV A.31452-003 (1), 105 mm SL, NMV A.31452-004 (1), 124 mm SL, NMV A.31452-005 (1), 92.0 mm SL, Upper Prince Regent at confluence with Pitta Creek, Prince Regent River, 15° 50' 56.82'' S, 125° 39' 0.41'' E, July 30, 2013, obtained with gill nets in a deep, clear pool at the confluence of the two streams by J. J. Shelley and M. C. Le Feuvre.

Non-type material (examined): seven specimens, 59–145 mm SL, WAM P.25031.005 (3), 59–68 mm SL, Upper Prince Regent River , Prince Regent River, (?) 15° 50' 56.82'' S, 125° 39' 0.41'' E, August 20, 1974, obtained with a spotlight and dip net on the edge of a stagnant pool with murky water over a mud bottom by G. Allen ; WAM P.25040.003 (4), 120–145 mm SL, Youwanjela Creek , Prince Regent River, (?) 15° 34' 0.0'' S, 125° 25' 0.0'' E, August 31, 1974, obtained using 0.5 kg of derris powder over rock bottom at depths to 1 m, in clear water, by G. Allen. See remarks for further details regarding these specimens.

Diagnosis: A large species of Syncomistes (recorded up to 250 mm SL, commonly 120–170 mm SL). Syncomistes versicolor sp. nov. differs from all other species within the Syncomistes complex by a combination of the following characters: lower jaw distinctly pointed when viewed from below, making a ‘V-shape’ in individuals> 65 mm ( Fig. 5c ); mouth subterminal; 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 ( Fig. 6g ); ventral profile distinctly convex; 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; head distinctly pointed in adults; jaw long relative to head length> 31.0 in HL; restricted to the Prince Regent River of the northwestern Kimberley Plateau.

Description: See Table 27 for a summary of meristic variation by type material and other material examined and Table S22 meristic variation across all specimens combined. Dorsal fin spines XII (XI–XII), rays 12 (12–13); anal fin spines III, rays 10 (9–11); caudal fin rays 11+8+7+11 (10–12+8+7+10–11, n = 5); pectoral fin rays 15; pelvic spines I, rays 5; vertebrae 11+14 = 25 (n = 6); lateral line scales 50 (49–51); scales above lateral line 10 (9– 11); scales below lateral line 20 (19–22); pre-dorsal scales 16 (14–17); cheek scale rows 4 (3–5); caudal peduncle scales 31 (31–34); gill rakers on first arch 10+18 = 28 (9–10+15–19 = 24–29); opercular spines 2; preopercular spines 18 (14–25), most posterior preopercular spine approximately in line with posterior edge of orbit on vertical plane.

See Table 28 for a summary of morphometric variation by type material and other material examined and Table S23 morphometric variation across all specimens combined. Body slightly compressed, with dorsal profile slightly more steeply angled than ventral profile, which is similarly convex. Dorsal profile begins with concave notch behind upper lip, steep rise, convex to interorbital, straight to occiput, convex to dorsal fin origin, convex to just beyond base of last dorsal ray, then horizontal to caudal fin base. Ventral profile on underside of head straight and angled downward, convex from back of head to last soft anal ray, then horizontal to caudal fin base. Lateral line continuous from behind head to base of caudal fin, and approximately parallel to dorsal profile. Body depth at dorsal fin origin 34.3 (31.8–37.1) % SL; body depth at anal fin origin 30.4 (28.2–32.8) % SL; caudal peduncle length 17.5 (16.5–18.9) % SL; caudal peduncle depth 12.6 (11.9–13.8) % SL; pre-anus length 67.2 (66.7–68.8) % SL. Head length 30.1 (29.3–30.8) % SL; head pointed; snout length 45.3 (43.6–47.5) % HL; upper-jaw length 32.5 (31.3–35.3) % HL; jaws equal throughout development; jaw width 36.1 (33.9–40.0) % HL. Teeth laterally compressed, narrow and short relative to Syncomistes , ‘peg-shaped’ with anterior and posterior edges running straight and parallel from tooth base, tapering slightly at apical region to a rounded point (Tooth Morphotype 4; Fig. 6g ); teeth fitted closely together but not overlapping, laterally pointed in lower jaw, extending beyond outer edge of lip. Outer row of large teeth with 4 inner rows of smaller teeth on both jaws, embedded in jelly-like gum, reducing in size towards back rows; teeth on outer row of upper jaw 114 (70–137) number varying with size, 8.1 (5.9–11.3) / mm when standardised with upper jaw length; teeth on outer row of lower jaw 117 (70–142) number varying with size, 8.8 (7.9–10.2) / mm when standardised with upper jaw length; toothless medial hump present on dorsal surface at symphysis of lower jaw, opposite toothless region of upper jaw; lower jaw distinctly V-shaped in adults and rounded in juveniles (<65 mm) when viewed from below, wider than it is long (Morphotype 4; Fig. 5d ). Lower jaw flattened when viewed laterally. Orbital diameter 20.3 (18.1–25.0) % HL; inter-orbital width 30 (27.3– 33.6) % HL; inter-orbital smooth and not scaled; post-orbital length 38 (37.8–39.5) % HL. Lower opercular spine is longer and more robust than upper opercular spine, sometimes extends beyond edge of opercular membrane; Preopercular spines serrate, reducing in size dorsally and anteriorly, anteriormost spine just behind mid-point of orbit. Intestinal pattern of adults highly convoluted; large amount of looping to left of stomach; juveniles with less convoluted pattern.

Dorsal fin origin posterior to vertical plane through pectoral fin origin, anterior to pelvic fin origin; terminates at base of last dorsal ray; dorsal fin sheath scales 2; 7th dorsal spine longest (5th–7th), 12.8 (12.4–13.7) % SL; progressively shorter towards first and last spine; last dorsal spine fully joined to first dorsal ray by membrane; 3rd dorsal ray longest (1st–4th), 14.8 (13.1–16.6) % SL; dorsal margin of rayed portion is rounded until tip of last ray; dorsal fin base length 53.5 (50.9–55.8) % SL; dorsal fin length 60.3 (56.5–63.9) % SL; pre-dorsal fin length 40.2 (38.5–41.5) % SL. Anal fin origin immediately posterior to base of last dorsal fin spine; terminates at base of last ray; anal fin sheath scales 4 (3–4); 2nd anal spine longest, 11.9 (10.6–12.8) % SL; 1 st anal ray longest (1st–2nd), 17.2 (14.7–18.5) % SL; rays progressively shorter to last ray; margin of rayed portion is rounded; anal fin base length 16.4 (15.0–17.7) % SL; anal fin length 24 (23.4–26.0) % SL; pre-anal fin length 71.3 (70.6–73.0) % SL. Caudal fin slightly emarginate in juveniles, emarginate in adults; upper caudal lobe length 26.3 (24.0–30.1) % SL; middle caudal ray length 18.3 (17.6–20.6) % SL. Pectoral fin length 20.5 (19.5–22.3) % SL; pre-pectoral fin length 28.9 (28.4–31.0) % SL. Pelvic spine length 11.4 (10.7–12.2) % SL; 1 st pelvic ray longest (1st–2nd), 20.5 (19.2–22.5) % SL, then progressively shorter; pelvic fin length 21.8 (20.0–24.5) % SL; pre-pelvic fin length 38.6 (38.0–41.1) % SL.

Colour when fresh: Exhibits impressive colour variation that appears to be related to ontogenetic shifts. Body of juveniles (<75 mm) light gold in colour. Darker dorsally, becoming lighter, even white, along the ventral surface. Olive green iridescent tinge along lateral line and on operculum. Horizontal gold stripe with an olive green tinge running below eye to snout, and a dark spot is present on upper edge of gill cover. Posterior scale margins have a dark band. Membranes and spines of spinous dorsal light gold, for the basal three-quarters, black at the tips. The membranes of soft are uniformly light gold. Membranes of spinous and soft anal light gold with a dark blotch on middle of rays. Pelvics light gold. Pectorals clear. Caudal darker gold, lighter at fin edge.

Body of fish> 75 mm <140 mm gold in colour. Darker dorsally, becoming lighter along the ventral surface. Olive green iridescent tinge on operculum. Gold stripe with an olive green tinged stripe running below eye to snout, and a dark spot is present on upper edge of gill cover. Membranes of spinous dorsal dusky, spines gold for the basal three-quarters, black at the tips. The membranes of soft are dusky. Membranes of spinous and soft anal uniformly black. Pelvics black. Pectorals clear. Caudal gold to dark, lighter at fin edge.

Body of adults> 140 mm uniformly black in colour, lighter on ventral surface. Olive green iridescent tinge on operculum and speckled on body. Olive green tinged stripe running below eye to snout. Membranes of spinous dorsal uniformly dusky, spines dark gold, black at the tips. The membranes of soft are dusky with a dark blotch on middle of rays. Membranes of spinous and soft anal uniformly black. Pelvics black. Pectorals clear. Caudal black, lighter at fin edge. No stripes are present on the sides of juveniles or adults.

Colour when preserved: Juveniles and adults uniformly dark brown to black with hints faints hints of pale colouration on the ventral surface. Brown when viewed ventrally. Lateral line is may be distinctly pale or dark brown in colouration. All fins dark brown to black.

Distribution: See Fig. 27 . Found throughout the Prince Regent River in the northern Kimberley. Ecology: Adults prefer deeper, slow flowing sections of creeks and rivers. Juveniles found in shallow, still waters or occasionally in riffle habitat. Often observed shoaling in the middle of the water column around snags, also observed in large schools (> 50 fish) patrolling up and down stream reaches. Found in clear waters over rocky substrates, often where algae is abundant. Segregation by size/age is apparent with large (> 200 mm) adult fishes appearing restricted to the lower catchment, while juveniles and sub-adults only present in the upper catchment. Nothing is known about its reproductive biology. Diet primarily consists of filamentous algae that is scraped off rocks with its modified teeth.

Comparison: Broadly similar morphological grouping to Syncomistes holsworthi , 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 in adults that is wider than it is long (jaw is U-shaped in juveniles <65 mm).

Unique in appearance although, most closely resembles Syncomistes holsworthi . Syncomistes versicolor can be distinguished by, on average, having more anal rays 10 (9–11) versus 8 (7–9), more scale rows between the lateral line and pelvic fin base 20 (19–22) versus 22 (19–24), less gill rakers on the lower arch 18 (17–19) versus 20 (18– 22) and in total 28 (27–29) versus 30 (28–34), longer postorbital length 41.4 (39.3–44.9) % HL versus 41.4 (39.3– 44.9) % HL, shorter snout length 40.0 (30.9–43.3) % HL versus 40.0 (30.9–43.3) % HL, shorter jaw length 28.5 (25.0–38.8) % HL versus 28.5 (25.0–38.8) % HL, and shorter anal ray length 15.5 (13.3–16.6) % SL versus 15.5 (13.3–16.6) % SL. Body colour is variable, although overall colour ranges from gold in juveniles to black in adults, rather than silver in juveniles and adults ( S. holsworthi ), olive green / blue in juveniles to black in adults ( S. dilliensis ), or olive green to light brown in juveniles and adults ( S. rastellus ).

Etymology: The specific name versicolor is Latin for many-coloured and refers to the distinct changes in the colour of the species at different stages in its ontogeny.

Remarks: Large bodied (> 140 mm) adults (relative to the species) were only caught in the lower reaches of the Prince Regent River, while smaller bodied fish were mostly caught in the upper reaches. Is sympatric with S. moranensis . WAM P.25031.005 and WAM P.25040.00 are listed in Allen (1975) as comprising 7 specimens from the Prince Regent, 59–145 mm, referable to S. trigonicus . These specimens are referred to in the original description of S. trigonicus as follows “Additional material identified as this species but not seen by me was collected at other localities in the Roe and Prince Regent rivers (species B of Allen, 1975)” (Vari 1978). Examination of these specimens as part of this study determined that these specimens are in fact S. versicolor . Therefore, the known geographic range of S. trigonicus no longer includes the Prince Regent River.

Figures

FIGURE 5.

FIGURE 6.

FIGURE 26.

FIGURE 27.

Tables

TABLE 27. Summary of meristic variation in Syncomistes versicolor sp. nov. (values for number of teeth of upper and lower jaw are per mm of jaw length).

	Holotype	Paratypes (N = 8)
Character		Mode	Mean	Min.	Max.	S.D.
DS	12	12	11.9	11	12	0.35
DR	13	12	12.1	12	13	0.35
AS	3	3	3.0	3	3	0.00
AR	9	10	9.9	9	11	0.83
PecR	15	15	15.0	15	15	0.00
PelS	1	1	1.0	1	1	0.00
PelR	5	5	5.0	5	5	0.00
UUCR	12	11	10.8	10	12	0.84
UBCR	8	8	8.0	8	8	0.00
LBCR	7	7	7.0	7	7	0.00
LUCR	11	11	10.8	10	11	0.45
LLSc	50	50	50.0	49	51	0.93
LD	11	10	10.1	9	11	0.64
LA	22	20	19.6	19	21	0.74
PDSc	16	16	16.0	14	17	1.07
DSSc	2	2	2.0	2	2	0.00
ASSc	4	4	3.6	3	4	0.52
CScR	4	4	4.1	3	5	0.64
CPSc	33	31	32.0	31	34	1.41
GRup	10	10	9.9	9	10	0.35
GRlow	18	18	17.8	15	19	1.39
GRtot	28	28	27.6	24	29	1.69
PcV	11	11	11.0	11	11	0.00
CV	14	14	14.0	14	14	0.00
TV	25	25	25.0	25	25	0.00
LDR	3	4	3.1	1	4	1.13
LDS	7	6	5.9	5	6	0.35
LAR	1	1	1.3	1	2	0.46
LAS	2	2	2.0	2	2	0.00
LPR	1	2	1.6	1	2	0.52
Tup	8.2	9	9.1	7.8	10.7	0.97
Tlow	8.4	8	8.8	7.9	10.2	0.84
TRup	4	4	3.9	3	4	0.35
TRlow	4	4	3.9	3	4	0.35
OS	2	2	2.0	2	2	0.00
PS	18	18	18.9	14	25	4.22

TABLE 28. Morphometric variation in Syncomistes versicolor sp.nov. (values are percentagesof denominators in ratios, except for SL).

	Holotype	Paratypes (N = 8)
Character		Mean			Min.	Max.	S.D.
SL (mm)	145.0	114.3			70.8	168.1
BDd / SL	37.1	33.9			31.9	35.8	1.29
BDa / SL	32.8	30.1			28.2	32.8	1.78
CPL / SL	17.3	17.5			16.5	18.9	0.77
CPD / SL	13.3	12.5			11.9	13.8	0.71
HL / SL	29.6	30.1			29.3	30.8	0.59
OD / HL	18.9	20.4			18.1	25.0	2.35
IoW / HL	32.0	29.8			27.3	33.6	1.94
PoL / HL	38.2	38.0			35.8	39.5	1.22
SnL / HL	47.4	45.0			42.9	47.4	1.55
JLup / HL	32.5	32.4			30.2	35.3	1.80
JW / HL	36.5	36.0			33.0	40.0	2.67
PDFL / SL	41.2	40.1			38.5	41.5	1.12
PPecL / SL	26.8	29.2			27.5	31.0	1.28
PPelL / SL	36.8	38.8			37.4	41.1	1.09
PAL / SL	67.7	67.1			66.1	68.8	0.88
PAfL / SL	72.4	71.2			70.3	73.0	1.00
DFBL / SL	54.8	53.3			50.9	55.8	2.03
DFL / SL	62.9	60.0			56.5	63.9	2.54
DFRL / SL	15.2	14.7			13.1	16.6	1.16
DFSL / SL	12.4	12.9			12.0	13.7	0.60
AFBL / SL	15.6	16.5			15.0	17.7	0.86
AFL / SL	26.0	23.7			23.4	24.3	0.32
AFSL / SL	11.9	11.9			10.5	12.7	0.75
AFRL / SL	17.3	17.2			14.7	18.5	1.18
PecL / SL	21.0	20.4			19.5	22.3	0.95
PelL / SL	21.8	21.8			20.0	24.5	1.57
PelSL / SL	12.1	11.3			10.3	12.2	0.73
PelRL / SL	21.6	20.4			19.2	22.5	1.33
CLLup / SL	27.9	26.1			23.9	30.1	2.43
CLLmid / SL	18.9	18.2			16.6	20.6	1.51