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Dorsal spines (total): 17-19; Dorsal soft rays (total): 8-10; Anal spines: 3-3; Anal soft rays: 7-9. Diagnosis: The presence of bicuspid teeth in the anterior portion of the outer row on both the upper and lower jaws and a moderately sloped ethmo-vomerine block with a swollen rostral tip place this species in Maylandia (Ref. 93436). The presence of a black submarginal band in the dorsal fin in combination with distinct black lateral bars on a blue and/or yellow flank and with yellow pigment on the cheek and breast distinguish males of this species from those of all other members of the genus except from those of the Maleri Island population of M. flavifemina; Maylandia nigrodorsalis can be distinguished from M. flavifemina by a deeper cheek, being 25,3-32,0% of body depth in M. nigrodorsalis vs. 20,3-24,8% in M. flavifemina from Maleri Island (Ref. 93436). Female Maylandia nigrodorsalis are distinguished from all other female Maylandia, except from those of M. lundoense, by the presence of a black submarginal band in the dorsal fin; female M. nigrodorsalis cannot reliably be distinguished from those of M. lundoense (Ref. 93436).
Description: Moderately compact species with greatest body depth at about base of ninth dorsal-spine (Ref. 93436). Dorsal body profile with gradual downward curve to soft-rayed portion of dorsal fin, then more acute curve to posterior origin of dorsal fin, gradual taper to caudal fin; ventral body profile slightly convex between pelvic and anal fin, then rounded to caudal fin; dorsal head profile concave to straight between snout tip and interorbital, with about 55° angle with body axis, then round to dorsal-fin origin (Ref. 93436). Eye about one and a half times depth preorbital and in ¾ of anterior half head with posterior ¼ orbit posterior of vertical median head; snout short with isognathous to slightly prognathous jaws; teeth on lower jaw in 3-5 rows with outer row bicuspid and inner rows tricuspid (Ref. 93436). Dorsal fin with 17-19 spines and 8-10 rays; anal fin with 3 spines and 7-9 rays; first 5 or 6 dorsal-fin spines gradually longer in length posteriorly with first spine about half the length of fourth spine; last 12 dorsal-fin spines slightly increasing in length posteriorly with last spine longest; soft dorsal with subacuminate tip, third or fourth ray longest, reaching to about ¼ of caudal fin in males and to base caudal fin in females; anal-fin spines progressively longer posteriorly; fourth or fifth ray longest, length to almost middle caudal fin in some males, to about base caudal fin in females; caudal fin subtruncate to emarginate; pelvic fin not to anal fin in females, length in males to first anal-fin rays; pectoral fin rounded, paddle-shaped, to vertical through base of 12th or 13th dorsal spine (Ref. 93436). Flank scales large, ctenoid; abrupt difference to small scales on breast and belly; cheek with 4-6 rows of small scales; rayed portions dorsal and anal fins with few tiny scales in proximal margin; tiny scales over proximal ¾ of caudal fin (Ref. 93436).
Colouration: The different populations have different colouration characteristics (Ref. 93436). Males of the N'kolongwe population with light blue flank and 6-9 black bars; belly yellow; caudal peduncle yellow/brown; interorbital light blue with 1 or 2 black interorbital bars; cheek and preopercle dark brown; dark blue gray opercle with black opercle spot; dorsal fin proximally yellow/orange with extensions of lateral bars, black/gray submarginal band, white/light-blue lappets, posterior 5 rays orange/brown with light-blue membrane; caudal fin yellow/brown with dorsal and ventral margin black; anal fin black with 2 or 3 yellow ocelli in posterior margin; pectoral fin with black rays and clear membranes; pelvic fin black with white leading edge (Ref. 93436). Females of the N'kolongwe population with bluish brown flank and 6-9 dark brown lateral bars; center of lateral scales brown; caudal peduncle brown; head brown with 1-2 faint blue interorbital bars; green/blue highlights on opercle; throat gray/brown; dorsal fin brown with darker submarginal band, orange/yellow lappets; caudal fin dark brown with blue spots on membranes; orange/yellow posterior margin; anal fin dark brown/yellow, with no or just a single small yellow spot in posterior margin; pectoral fin with gray rays and clear membranes; pelvic fin with white leading edge, black rays, and clear membranes (Ref. 93436). Breeding males of the Chiloelo and Charlie's Bay populations with dark blue flank and 6-9 lateral bars; belly dark gray/yellow; interorbital black/dark blue with blue interorbital bars sometimes present; cheek with blue and yellow markings; throat gray; dorsal fin black with gray/yellow trailing part, white lappets; caudal fin blue with wide yellow posterior margin and black dorsal and ventral margins; anal fin black with yellow/gray posterior margin and 2-6 ocelli; pectoral fin with black rays and clear membranes; pelvic fin black with blue/white leading edge and yellow posterior margin (Ref. 93436). Females of the Chiloelo and Charlie's Bay population with brown/beige flank and 7-9 gray lateral bars; brown/orange spot on anterior portion of scales; head dark gray with 2 light gray/green interorbital bars; cheek light gray; lower jaw with blue highlights; branchiostegal membranes bluish gray; blue opercle spot; dorsal fin brown/dark gray with white lappets and dark submarginal band sometimes present; caudal fin gray with black ventral and dorsal margin; anal fin gray fading to yellow with 1 or 2 small yellow spots in posterior margin; pectoral fin with gray rays and clear membranes; pelvic fin gray with white leading edge (Ref. 93436). Breeding males of the Thundu population with light-blue flank and 6-9 gray/black lateral bars; caudal peduncle blue/gray; belly gray/yellow; interorbital brown/orange with 1-2 light-blue interorbital bars; cheek brown with yellow highlights; throat brown/orange; dark green opercle spot; dorsal fin light blue and yellow highlights with black submarginal band, white marginal band, and orange lappets; caudal fin with black dorsal and ventral margins with light-blue/yellow edge, orange rays, and blue membranes; anal fin light blue with wide black submarginal band, often over 90% of fin, and white/light-blue lappets, 1-6 orange/yellow ocelli in posterior margin; pectoral fin with blue/gray rays and clear membranes; pelvic fin black with white leading edge (Ref. 93436). Females of Thundu population with light-brown ground colour and 7-9 faint dark-brown bars; white belly; head brown/beige with white/light brown throat; with occasional black opercle spot; dorsal fin brown with light blue spots in membrane, white lappets with orange/yellow tips; caudal fin light brown with orange/yellow posterior margin; anal fin yellow/brown with 0-2 small yellow spots in posterior margin; pectoral fin clear; pelvic fin orange/yellow with white leading edge (Ref. 93436). Males of the Nkhungu population with yellow flank and 7-10 black bars; center of many flank scales blue; belly yellow/gray-blue; interorbital gray/yellow with 1 pale blue interorbital bar; opercle brown/yellow with dark orange opercle spot; throat orange; dorsal fin blue with black submarginal band, a blue/green margin, and rust-orange lappets; caudal fin with blue rays, black membranes, and orange distal margin; anal fin with 2-7 yellow ocelli in posterior margin and white/blue lappets; pectoral fin with gray rays and clear membranes; pelvic fin black with white leading edge (Ref. 93436). Females of the Nkhungu population light brown/beige; scales outlined in blue; white belly; head brown with white throat; dorsal fin light brown with orange/white lappets, light spots in membranes; caudal fin with brown rays and clear membranes with distal yellow margin; anal fin proximally white and distally yellow; pectoral fin clear; pelvic fin with clear rays and yellow membranes; white leading edge (Ref. 93436). |