Diagnosis: A moderately-sloped head and bicuspid teeth in the outer row of the jaws place this species in Maylandia (Ref. 86409). The absence of a black submarginal band in the dorsal fin in conjunction with a yellow gular region and branchiostegal membranes, and the light-brown coloured females that have yellow fin margins distinguish M. glaucos from other members of Maylandia, except M. chrysomallos and M. benetos; there are generally fewer teeth in the outer row of the lower left jaw, range 14–19, of M. glaucos compared to M. chrysomallos, range 15–25, and more compared to M. benetos, range 9–13 (Ref. 86409). On the basis of colour pattern, females of M. glaucos cannot reliably be distinguished from those of most other members of the Aurora group, but they differ from those of M. xanthos by a shorter lower jaw, 28.8–32.8% of head length vs. 34.6–36.7%; and from those of M. aurora by 8–11 vertical bars below the dorsal fin vs. 6 in M. aurora (Ref. 86409).

Description: Dorsal snout profile slightly concave to straight; mouth cleft slightly downward to horizontal; jaws isognathous (Ref. 86409). Teeth on dentary in 2-3 rows, on premaxilla in 2 or 3 rows; outer row teeth typically bicuspid anteriorly and unicuspid posteriorly, middle rows when present tricuspid, innermost row unicuspid; lower pharyngeal jaw with numerous slender teeth with teeth in posterior row slightly larger; portion of upper dental arcade normally exposed when mouth closed; tips of teeth in premaxilla and dentary in V-shaped line with anteriormost in upper and lower jaw furthest apart and not touching in closed mouth (Ref. 86409). Lateral scales ctenoid (Ref. 86409).

Colouration: Breeding males light blue/gray laterally with 7 dark gray bars below dorsal fin and white belly; head light blue/gray with preorbital, cheek, and operculum light blue; darker blue opercular spot; yellow gular region and branchiostegals; dorsal fin blue with white lappets; caudal-fin rays gray with white/blue membranes; anal fin gray with 1-4 yellow ocelli; pelvic fin with white leading edge, first ray gray and remainder clear; pectoral fin clear (Ref. 86409). Lateral colouration of females gray dorsally and white ventrally; head gray with gray cheeks; blue/gray operculum with green highlights, gray/black opercular spot, and white gular region; dorsal fin gray with yellow/orange lappets; caudal-fin rays gray with clear membranes and faint yellow/orange spots; anal fin gray proximally and yellow distally without ocelli; pelvic fin with white leading edge and black submarginal band, membranes yellow to clear; pectoral fins clear (Ref. 86409).