Smallscale Tonguesole

Plain dark brown on the eye-side of body; body depth 4.3-5.0 times in SL; 21-22 scale rows between 2 lateral lines; with a single pelvic fin (Ref. 43281).

Potamodromous. Migrating within streams, migratory in rivers, e.g. Saliminus, Moxostoma, Labeo. Migrations should be cyclical and predictable and cover more than 100 km.

Dorsal soft rays (total): 117 - 119; Analsoft rays: 92 - 96

A strictly freshwater species found in large rivers. Found along the bottom where it feeds on benthic invertebrates. Marketed fresh (Ref.12693).

fisheries: commercial

Cynoglossus microlepis (Bleeker)

Plagusia microlepis Bleeker, 1951a:413 [type-locality: Borneo]; 1852:31.

Arelia microlepis.—Bleeker, 1859:184.

Cynoglossus microlepis.—Günther, 1862:495.—Bleeker, 1875:32, pl. 243: fig. 3.—Vaillant, 1893:101.—Weber and de Beaufort, 1929:190.—Smith, 1933:83; 1945:442.—Suvatti, 1950: 327.—Punpoka, 1964:65.

Cynoglossus xiphoideus Günther, 1862:495 [type-locality: Siam].—Bleeker, 1865a:33.—Kner, 1867:294.—Hora, 1923a: 182.—Smith, 1933:83; 1945:441.—Suvatti, 1950:329.—Chabanaud, 1951c:l.

Cynoglossus (Arelia) solum Sauvage, 1878:92 [type-locality: Mekong River].

Arelia solum Sauvage, 1883:151.

Cynoglossus feldmanni [not Bleeker].—Weber and de Beaufort [in part], 1929:192.

Cynoglossus trigrammus [not Günther].—Suvatti, 1950:329.—Punpoka, 1964:75 [Gulf of Thailand].

DESCRIPTION.—Based on 4 specimens, 142.0–231.0 mm SL.

Depth of body 20.07–22.51 (M = 20.84), length of head 19.05–20.35 (M = 20.21) percent of standard length. Migratory eye is much in advance of fixed eye, diameter of eye 5.00–6.67 (M = 5.50), interorbital space rather broad 6.67–8.51 (M = 7.54) percent in length of head. Two nostrils on ocular side, anterior nostril tubular, in front of fixed eye, posterior nostril simple, in posterior half of interorbital space. Snout obtusely pointed, 40.0–45.0 (M = 42.82) percent of length of head, rostral hook rather long, reaches below middle or posterior half of fixed eye. Maxillary extending to below posterior border of fixed eye or a little behind; angle of mouth extending to below vertical from posterior half of fixed eye, nearer to branchial opening than to tip of snout; tip of snout to angle of mouth 54.26–55.0 (M = 54.82), angle of mouth to branchial opening 40.0–48.94 (M = 44.11) percent of length of head.

Scales: Small, ctenoid on both sides, those on blind side weakly serrated.

Lateral-Line System: Three lateral lines on ocular side, midlateral line with 116–138 scales, 21–22 scales between middle and upper lateral lines. No lateral line on blind side.

Interlinear scale rows 21 22

Frequencies 5 2

Fins: Dorsal with 117–119 rays, anal with 92–96 rays, caudal 8 in 4 specimens (radiographs).

Vertebrae: 55–56, comprising 9 abdominal and 46–47 caudal elements in 4 specimens (radiographs).

Coloration: Upper side reddish brown with dark spots, lower whitish in preserved specimens.

Size: Largest specimen examined, 304 (270 + 34) mm, is from Sarawak, Borneo.

DISTRIBUTION.—Thailand, Cambodia, Vietnam, Borneo, and Sumatra. In strictly fresh water.

DIAGNOSIS AND