Freshwater Tongue Sole

Only 15 or 16 scales between dorsolateral and midlateral lines (Ref 9895).

Dorsal spines (total): 0; Dorsal soft rays (total): 110 - 116; Analspines: 0; Analsoft rays: 85 - 89; Vertebrae: 51 - 52

Inhabits main river channels and tributaries on soft mud or fine sand bottoms (Ref. 2847). Occurs in brackish estuaries and freshwater streams (Ref. 44894).

Cynoglossus heterolepis Weber

Cynoglossus heterolepis Weber, 1910:237 [type-locality: Lorentz R.]; 1913a:590 [Lorentz R., Bivak Is.].—Weber and de Beaufort, 1929:186, figs. 52, 53 (Lorentz R.).—Hardenberg, 1941:227 (Petpemboewe).—Munro, 1958:285.

DESCRIPTION.—Based on 4 specimens, 65–194 mm SL, including the holotype of C. heterolepis.

Depth of body 16.44–23.45 (M = 18.89), length of head 19.07–25.09 (M = 23.28) percent of standard length. Diameter of eye 3.23–5.97 (M = 5.08), interorbital space 3.23–5.71 (M = 4.37) percent of length of head. Two nostrils on ocular side, anterior nostril tubular, in front of lower eye, posterior nostril simple, in the middle of interorbital space. Snout obtusely pointed, 41.94–45.71 (M = 43.92) percent of length of head; rostral hook rather short, ends just in front of anterior nostril. Maxillary extending to a little behind fixed eye; angle of mouth extending below vertical from posterior border of fixed eye, nearer to branchial opening than to tip of snout; tip of snout to angle of mouth 43.24–57.14 (M = 51.06), angle of mouth to branchial opening 41.79–43.24 (M = 42.46) percent of length of head.

Scales: Ctenoid on both sides, those on blind side rather weakly serrated.

Lateral-Line System: Three lateral lines on ocular side, midlateral line with 100–120 scales, 15–16 scales between middle and upper lateral line. No lateral line on blind side.

Interlinear scale rows 15 16

Frequencies 2 2

Fins: Dorsal with 113–116 (M = 115) rays, anal with 86–89 (M = 88) rays, caudal 10 in 4 specimens (radiographs).

Vertebrae: 51–52, comprising 9 abdominal and 41–43 caudal elements in 4 specimens (radiographs).

Coloration: Upper side uniformly brownish with or without darker spots, lower whitish in preserved specimens.

Size: The largest specimen examined, 203 (194 + 9) mm, is the holotype from the Lorentz River, New Guinea.

DISTRIBUTION.—New Guinea (Lorentz River) and Australia (Northern Territory).

DIAGNOSIS AND

Cynoglossus heterolepis Weber, 1910

USNM 217318, Fly 75–32, 1: 153 mm.

Originally described from the Lorentz, this species is also known from the Oetoemboewe (the drainage immediately east of the Lorentz), the Upper Fly, and Arnhem Land (Menon, 1977:87–89). There are few specimens in museums; the largest reported is 194 mm.