Diagnosis: Polypterus palmas is distinguished from other species of the genus by the upper jaw longer than lower jaw, pectoral fin not reaching the level of the first dorsal fin ray and 27-32 scales between occiput and first dorsal fin ray (Ref. 2835, 28149, 42908, 81263).

Description: Subcylindrical body (Ref. 2835, 3054, 28149, 81263); the height of which is comprised 7,3 to 9,6 times in body length and head length 5,2 to 6,5 times (Ref. 2835, 81263). Head not flattened, 1,4 to 1,8 times longer than broad; upper jaw longer than lower jaw; eye diameter comprised 7,3 to 11,7 times in head length (Ref. 2835, 3054, 42908, 81263). Dorsal fin with 7-10 rays, followed by 16-17 dorsal and caudal articulated rays; anal fin with 12-14 rays; pectoral fin not reaching the level of the first dorsal fin ray; 15-17 caudal fin rays (Ref. 2835, 28149, 81263). Ganoid scales (Ref. 42904): 51-59 in lateral line, 33-39 around body, 22-32 between occiput and the first dorsal fin ray; lateral line scales simply perforated, not grooved and without posterior notched border (Ref. 2835, 28149, 51884, 81263).

Colouration: In alcohol, upper part of flanks and back grey greenish, marked with irregular dark grey to black blotches particularly in caudal part forming a dense and reticulate pattern; lower parts of head and body whitish (Ref. 2835, 28149, 81263). Dark spots on the dorsal fin ray membranes; the fleshy base of the pectoral fin with small spots on the posterior part; no dark colouration on pelvic and anal fin (Ref. 2835, 28149, 81263).