Diagnosis: A moderately-sloped head and bicuspid teeth in the outer row of the jaws place this species in Maylandia (Ref. 86409). Both males and females are light blue, fading to white ventrally, distinguishing them from all other members of Maylandia, except M. callainos; male M. nkhunguensis are distinguished from those of the similarly coloured M. chrysomallos from the Gome population, M. estherae, and M. callainos, the latter two species of the sediment-free rocky habitat, by the yellow base of the pectoral fin, vs. no yellow pigment in males of the other three species; female M. nkhunguensis are light blue, lighter than those of the only other known species with all-blue females, M. callainos, which are a darker cobalt-blue; female M. estherae are either brown or orange/red); Maylandia nkhunguensis is further distinguished from M. callainos by a shorter lower jaw, 29.4-34.1% of head length vs. 34.9-43.3% (Ref. 86409).

Description: Dorsal snout profile slightly concave to straight; mouth cleft with slightly downward angle; jaws isognathous; teeth on dentary in three rows, on premaxilla in three to four rows; outer row teeth typically bicuspid anteriorly and unicuspid posteriorly; inner rows tricuspid, innermost row unicuspid; lower pharyngeal jaw with numerous slender teeth with teeth in posterior row slightly larger; portion of upper dental arcade normally visible in closed mouth; tips of teeth in premaxilla and dentary in V-shaped line with anteriormost in upper and lower jaw furthest apart and separate in closed mouth (Ref. 86409). Lateral scales ctenoid (Ref. 86409).

Colouration: Breeding males pale blue laterally fading to white-blue ventrally; head entirely pale blue with white gular region; dorsal fin light blue with white-blue lappets; caudal-fin rays clear with blue membranes; anal fin light blue and 1-5 orange ocelli; pelvic fin light blue with white leading edge; pectoral fin clear with orange base (Ref. 86409). Females light blue fading to white ventrally; head light blue/gray, white gular region; dorsal fin light blue with orange lappets; caudal fin light blue; anal fin light blue with 1-4 orange ocelli; pelvic fin light blue/gray with white leading edge; pectoral fin clear with white base (Ref. 86409).