Periophthalmus gracilis Eggert, 1935

(Fig 4D; Table 2)

Material examined. USMFC (113) 00080, 1 ex., 31.7 mm SL, Sungai Burung Mangrove Forest –Site 1, coll. Jaafar Z. & Smither S., January 18, 2025.

Description. D1 X; D2 I,12; A I,10; P 13; LS 68; TRB 20; PDS 22. Head rounded; snout rounded. Mouth terminal, upper lip and snout anteriormost; jaw reaching back to below posterior half of eye. Body elongated, rounded anteriorly, more compressed posteriorly. Predorsal area covered with cycloid scales, extending anteriorly to posterior of eyes; opercle scaled. Pectoral fin base, prepelvic area and belly covered with cycloid scales; body scales cycloid to behind pectoral fin. First dorsal fin rounded, first spine longest; second dorsal fin high, rounded posteriorly; anal fin moderate, rounded posteriorly; pectoral fin oval; pelvic fin separated; caudal fin rounded. Head and body earthy brown to grey, white ventrally; trunk with seven oblique diagonally oriented slating brown bars; first dorsal fin translucent, single brown inframarginal band, ocellate spot located posteriorly; second dorsal fin with single black inframarginal band, scattering black spots near fin base; anal fin white; pectoral fin greenish grey; pelvic fin white; caudal fin grey with 7–8 rows of irregular black spotted line along fin rays.

Habitat. Mangrove forest floor with shallow puddles and sandy−muddy substrates.