From Boulenger (1910):
Petrocephalus cunganus, sp. n.
Depth of body equal to length of head, 3½ times in total length. Head slightly longer than deep, with convex upper profile; snout rounded, strongly projecting beyond mouth, 1/5 length of head; mouth below anterior border of eye, its width ¼ length of head ; teeth bicuspid, 11 in upper jaw, 24 in lower ; nostrils near lower border of eye ; eye ¼ length of head, 2/3 interorbital width. Dorsal 27, originating above first ray of anal; its length 1½ times in its distance from head and a little greater than its distance from caudal. Anal 32, equally distant from base of ventral and from base of caudal. Pectoral pointed, 2/3 length of head, not quite twice as Iong as ventral, extending beyond base of latter. Caudal scaled at the base, upper lobe pointed, lower rounded. Caudal peduncle 3 times as long as deep, ¾ length of head. 47 scales in the lateral line, 12/14 in transverse series on body, 16/14 in transverse series between dorsal and anal, 12 round caudal peduncle. Brown above, silvery beneath; fins brownish.
From Boulenger (1910): Total length 110 mm.
Holotype from the Quanza River at Cunga