Stolephorus advenus Wongratana, 1987

Hata, Harutaka & Motomura, Hiroyuki, 2023, Redescription and extended distribution of a poorly known Australian anchovy, Stolephorus advenus (Actinopterygii: Clupeiformes: Engraulidae), Acta Ichthyologica et Piscatoria 53, pp. 209-216 : 209

Stolephorus advenus Wongratana, 1987

English name: false Indian anchovy (Fig. 1

Stolephorus advenus Wongratana, 1987- Wongratana (1987a): 106, fig. 2 (type locality: north of Saulte Point, Cobourg Peninsula, Northern Territory, Australia).- Wongratana (1987b: 7 (Cobourg Peninsula, Northern Territory, Australia).- Whitehead et al. (1988): 403, unnumbered figs. (north of Saulte Point, Cobourg Peninsula, Northern Territory, Australia).- Wongratana et al. (1999): 1726, unnumbered figs. (north of Saulte Point, Cobourg Peninsula, Northern Territory, Australia).- Paxton et al. (2006): 314 (north of Saulte Point, Cobourg Peninsula, Northern Territory, Australia).- Hata et al. (2021): 332 (north of Saulte Point, Cobourg Peninsula, Northern Territory, Australia).

Material examined.

10 specimens, 49.1-79.6 mm SL, all specimens collected from Australia .

Holotype.

NTM S. 10031-153, 72.2 mm SL, holotype of Stolephorus advenus , north of Saulte Point, Cobourg Peninsula, Northern Territory, 18 Oct. 1981, H. Larson leg.

Non-type specimens.

CSIRO A 2911, 53.3 mm SL, Gulf of Carpentaria, approx. 13 km east of Sydney Island, Queensland (16°42′36″S, 139°34′48″E), 16.5 m depth; CSIRO A 2916, 56.3 mm SL, CSIRO A 2917, 52.3 mm SL, Gulf of Carpentaria, approx. 14 km east of Sydney Island, Queensland (16°40′12″S, 139°36′30″E), 14.6 m depth; CSIRO B 288, 3 specimens, 53.8-56.3 mm SL, Gulf of Carpentaria, approx. 9 km east of Sydney Island, Queensland (16°43′00″S, 139°33′00″E), 16.5 m depth; CSIRO CA 2555, 74.2 mm SL, approx. 20 km east of Tasman Point, Groote Eylandt, Northern Territory (14°20′S, 136°10′E), 18 m depth; CSIRO CA 2688, 79.6mm SL, north of Groote Eylandt, Gulf of Carpentaria, Northern Territory; NTM S. 13803-003, 49.1 mm SL, Howard Channel, Clarence Strait, Northern Territory (12°05′S, 131°02′E).

Diagnosis.

A species of Stolephorus with the following combination of characters: maxilla short, 13.7%-14.5% of SL, its posterior tip not reaching anterior margin of preopercle; posterior margin of preopercle convex, rounded; no predorsal scutes; prepelvic scutes 6 or 7 (modally 7); pelvic scute without spine; dorsal fin with three unbranched and 12-15 (14) branched rays; anal fin with three unbranched and 15-17 (16) branched rays, its origin just below base of ninth to eleventh dorsal-fin ray; 1UGR 17-19 (18), 1LGR 24-27 (25), 1TGR 42-45 (42), 2UGR 10-13 (11), 2LGR 20-23 (22), 2TGR 30-35 (33), 3UGR 8-11 (9), 3LGR 11-13 (12), 3TGR 20-22 (21), 4UGR 6-9 (7), 4LGT 9-10 (9), 4TGR 15-18 (17); gill rakers 3 or 4 (4) on posterior face of third gill arch; transverse scales 8; pseudobranchial filaments 15-18 (16); total vertebrae 41 or 42 (42); pelvic fin short, 7.6%-8.0% of SL, tip of depressed pelvic fin not reaching posteriorly to vertical through dorsal-fin origin; head short, 21.6%-22.9% of SL; body rather deep, 17.4%-20.9% of SL; pectoral fin rather long, 13.5%-14.2% of SL; pairs of dark patches on parietal area (sometimes also on occipital area); no dark lines on dorsum; no black spots on suborbital area and tip of lower jaw; no melanophores on bases of dorsal and anal fins, and pectoral fin.

Description.

Counts and measurements, expressed as percentages of SL, given in Tables 1 and 2 . Body laterally compressed, elongate, deepest at dorsal fin origin. Dorsal profile of head and body gently elevated from snout tip to dorsal-fin origin, thereafter gradually lowering to uppermost point of caudal-fin base. Ventral profile of head and body gently lowering from lower-jaw tip to below pectoral fin, thereafter nearly straight (parallel to body axis) to anal-fin origin, gradually elevated along anal-fin base, thereafter nearly straight (parallel to body axis) to lowermost point of caudal-fin base. Abdomen rounded, covered with six or seven spine-like prepelvic scutes anterior to pelvic fin insertion. Pelvic scute without spine. Postpelvic and predorsal scutes absent. Anus just anterior to anal-fin origin. Snout round, projecting, length less than eye diameter. Eye large, round, covered with adipose eyelid, positioned laterally on head dorsal to horizontal through pectoral-fin insertion, visible in dorsal view. Pupil round. Orbit elliptical. Nostrils close to each other, anterior to orbit. Mouth large, inferior, ventral to body axis, extending backward beyond posterior margin of eye. Maxilla short, its posterior tip slightly short of anterior margin of preopercle. Lower jaw slender. Single row of conical teeth on each jaw and palatines. Several conical teeth on vomer. Small fine teeth patch on pterygoids. No teeth on upper edge of hyoid. Several rows of conical teeth on upper edges of basihyal. Posterior margins of preopercle, subopercle and opercle rounded, smooth. Gill membrane without serrations. Interorbital space flat. Interorbital width less than eye diameter. Pseudobranchial filaments present, length of longest filament less than eye diameter. Gill rakers long, slender, rough, visible from side of head when mouth opened. Isthmus muscle long, reaching anteriorly posterior margin of gill membranes. Urohyal hidden by isthmus muscle (not visible without dissection). Gill membrane on each side joined distally, most of isthmus muscle exposed (not covered by gill membrane). Head scales absent. Fins scaleless, except for broad triangular sheath of scales on caudal fin. Dorsal-fin origin posterior to vertical through base of last pelvic-fin ray, slightly posterior to middle of body. Dorsal and anal fins with three anteriormost rays closely spaced and unbranched. First dorsal- and anal-fin rays minute. Dorsal profile of dorsal fin elevated from dorsal-fin origin to third fin ray tip, thereafter lowering to last dorsal-fin ray tip. Anal-fin origin just below base of ninth to eleventh dorsal-fin ray. Posterior tip of depressed anal fin not reaching caudal-fin base. Uppermost pectoral-fin ray unbranched, inserted below midline of body. Posterior tip of pectoral fin not reaching vertical through pelvic-fin insertion. Dorsal, ventral, and posterior contours of pectoral fin nearly straight. Pelvic fin shorter than pectoral fin; pelvic-fin insertion anterior to vertical through dorsal-fin origin. Posterior tip of depressed pelvic fin not reaching vertical through dorsal-fin origin. Caudal fin forked, tips of both lobes pointed.

Coloration of preserved specimens.

Body uniformly pale ivory or pale brown. Indistinct light brown longitudinal band narrower than eye running from opercle to caudal-fin base. Paired dark patches on parietal regions, but no melanophores on occipital area (a few melanophores in some specimens). No dark lines on dorsum. No melanophores on dorsal, pectoral, pelvic, and anal fins, and lateral surface of head. Melanophores scattered along caudal-fin rays. Fins pale, semi-transparent. Melanophores scattered on gill rakers, gill arch, gill filaments, inner side of hyoid, and pseudobranchial.

Distribution.

Stolephorus advenus has been recorded along the northern coast of Australia from Clarence Strait, Northern Territory to southern Gulf of Carpentaria (around Sydney Island, Queensland) ( Wongratana 1987a; Whitehead et al. 1988; Wongratana et al. 1999, this study; Fig. 2 ).

Figures

Figure 1. Specimens of Stolephorus advenus [A: holotype, NTM S. 10031 - 153, 72.2 mm SL, Cobourg Peinsula, Northern Territory, Australia (photograph taken by S. Tashiro); B: lateral, C: dorsal, and D: ventral views of non-type specimen, NTM S. 13803 - 003, 49.1 mm SL, Clarence Strait, Northern Territory, Australia (melanophores absent on occipital region); E: lateral view of whole body and F: dorsal view of head of non-type specimen, CSIRO CA 2688, 79.6 mm SL, Gulf of Carpentaria, Northern Territory (melanophores scattered on occipital region); scale bars indicate 0.5 mm].

Figure 2. Distributional records of Stolephorus advenus based on specimens examined in this study (red star: type locality; red dot: non-type specimens).