Diagnosis: pharyngeal teeth fine and rather crowded; lower dentigerous area with more rounded lobes than in other subspecies; pectoral fin length less than 37% standard length (Ref. 2). Possession of mtDNA cleavage phenotypes BclI-B, HhaI-D, MboI-A and MboII-E (Ref. 27554).

Description: sometimes with only 4 lateral-line openings in the preorbital bone on one or both sides; teeth in 3-4 series, sometimes part of a fifth, with rather slender shafts; micro-branchiospines present on outer sides of second to fourth arches; scales in 2-3 rows on cheek; genital papilla of male conical or with a terminal notch (Ref. 2).

Coloration: recently preserved specimens dark, the dark spots on the scales becoming smaller towards the ventral surface; vertical series of dark spots on the caudal are present but less regular than in O. n. niloticus (Ref. 2). Mature males: anal fin is black between rays; dorsal fin grey with series of black spots on the soft part and posterior part of spinous dorsal fin; lappets with black edge (Ref. 2). Females and young: melanin more diffuse (Ref. 2).