Diagnosis: Haplochromis labiatus differs from all known species of Haplochromis from the Lake Edward system by a combination of a blunt snout, retro- to isognathous jaws, deep lower jaw with blunt teeth, and lobed lips (Ref. 126507). It can be confused with H. lobatus as both have lobed lips, a small gape, a curved upper jaw with a relatively long premexillary pedicel, 78.7-111.4% of upper jaw length, stout and unicuspid outer teeth that strongly decrease in size, and a lower jaw set anteriorly with procumbently implanted outer teeth on the anterior margin of the lower jaw, 40-60° to vertical; it differs from this species by a straight to convex vs. straight to concave head, and a blunt and more broad snout vs. elongated and slender snout; it differs further in its trophic morphology: lower jaw slightly shorter, 27.7-34.3% of head length vs. 31.2-40.7%, and more broa, 71.4-92.4% of lower jaw length vs. 48.5-70.5%, jaws iso- to retrognathous vs. iso- to strongly prognathous, and anteriormost outer teeth in lower jaw more closely set, 0-1 vs. 1-2 outer tooth widths between adjacent teeth, and with shorter major cusps (Ref. 126507). Haplochromis labiatus resembles H. paucidens from Lake Kivu by a blunt head, lobed lips, and insectivorous diet; it differs by a shallower lacrimal and a larger eye, lacrimal depth 36.3-50.9% of eye diameter vs. 51.7-62.4%, and a slightly broader head, 46.1-51.0% of head length vs. 43.9-47.1%; it further differs by mainly unicuspid vs. bicuspid outer teeth with stouter major cusps and mainly unicuspid vs. tricuspid inner teeth; no notable difference in dominant male colouration has been observed but a piebald colouration is seemingly absent in H. labiatus, while it is frequently observed in H. paucidens (Ref. 126507). Haplochromis labiatus resembles superficially H. chilotes from Lake Victoria by lobed lips but differs by a blunt vs. acute snout and a larger eye, eye diameter 31.0-36.9% of head length vs. 21.8-28.6% (Ref. 126507).

Description: Body deep; head straight to moderately convex; snout blunt and steep with an inclination of 40-55° (Ref. 126507). Jaws iso-to retrognathous; gape small and with an inclination of 10-30°; maxilla extends to between nostril and anterior margin of orbit; lower jaw stout, short, broad, anteriorly deep, posteriorly very deep, and with a rounded outline anteroventrally in lateral view; uppr jaw stout, short, with dentigerous arm of premaxilla curving gently downwards, and with a long premaxillary pedicel in comparison to upper jaw length, 78.7-111.4% of upper jaw length; lips lobed uniformly over whole lenghts and oral mucosa very strongly thickened (Ref. 126507). Neurocranium with relatively deep preorbital region, and with deep and pyramidical supraoccipital crest (Ref. 126507). Chest scales small; transition to flank scales gradual; scales on longitudinal line 30-33; scales on upper lateral line 20-23, scales on lower lateral line 9-14, scales between dorsal fin and upper lateral line 5-8, scales between upper lateral line and anal fin 9-12, scales around caudal peduncle 16, scales between pectoral and pelvic fins 5-10, infraorbital cheek scales 2-4, postorbital cheek scales 7-11 (Ref. 126507). Outer oral teeth large, very stout, relatively few, and deeply embedded in oral mucosa; necks straight, long, and cylindrical; crowns slightly recurved, very short, and stout; major cusps blunt and equilateral to subequilateral; minor cusps, if present, short and blunt; cusp gaps narrow; dental arcades rounded and relatively slender; outer teeth regularly and closely set with 0-1 outer tooth width between adjacent teeth; lateral and posterior outer teeth with straight implantations and almost completely embedded in oral mucosa; three to five anteriormost outer teeth in lower jaw procumbently implanted on anterior margin of lower jaw, 40-60° to vertical, and in both jaws large and unicuspid in large specimens of more than 80 mm standard length, while in small specimens of less than 70 mm standard length uni-, weakly bi-, to rarely bicuspid and slightly symphyseally inclined; outer teeth strongly decrease in size lateral, abruptly in lower jaw; lateral outer teeth uni- to weakly bicuspid; in small specimens of less than 80 mm standard length mostly bicuspid; in large specimens of more than 90 mm standard length, 2-3 posteriormost outer teeth I upper jaw enlarged and more stout than adjacent teeth; tooth bands crescent-shaped and slender with 2-4 rows of inner teeth anteriorly that narrow laterad, until only outer rows remain; inner teeth uni- to weakly tricuspid, bluntly pointed, and widely and irregularly set on 1/2-1 outer tooth width from outer rows; inner teeth anteriorly in first row large and stout, while decreasing in size orally; anteriormost inner and outer teeth often abraded (Ref. 126507). Lower pharyngeal bone triangular and equally deep over entire length; pharyngeal teeth relatively slender and bluntly pointed with cylindrical to slightly constricted necks, bluntly pointed major cusps, concave major cusp gaps, and blunt minor cusps; teeth in posteriormost transverse row more stout, blunt, and weakly bicuspid; teeth in two median longitudinal rows stout (Ref. 126507). Caudal fin emarginate; dorsal and anal fins reach level between one scale anterior to and one scale posterior to caudal fin base; pectoral fins reach level between genital opening and first anal-fin spine; pelvic fins between genital opening and third anal-fin spine (Ref. 126507). Ceratobranchial gill rakers in outer row of first gill arch unifid and short, posteriormost rakers rarely bifid in large specimens of more than 80 mm standard length; epibranchial gill rakers short and relatively slender (Ref. 126507).

Colouration: Colouration in life of dominant males: body, cheeks, and operculum beige to blue with yellow sheen; dorsum with greenish sheen; chest dusky; flanks with 5-7 faint, dusky, and blue vertical stripes; snout and lower jaw turquoise; lips beige to dusky; nostril, interorbital, supraorbital, and vertical preopercular stripes and nape band faint and ill-defined; pectoral fins hyaline; pelvic fins black; dorsal fin dusky and anteriorly with black lappets; posteriorly orange-red lappets, and maculated orange-red between branched rays; anal fin white, base dusky, extensions bright yellow, and with 3-5 small orange egg spots, i.e., size of distance between rays, with black borders; caudal fin bright orange to orange-red and with dusky base (Ref. 126507). Colouration in life of females and juveniles: body beige with yellow sheen; dorsum with blue-green sheen; cheeks, operculum, chest, and belly white; flanks with 5-7 very faint dusky vertical stripes; pectoral fins hyaline, pelvic fins white; dorsal fin dusky and with black lappets; caudal fin dusky with yellow to orange extensions and dorsal part faintly maculated; anal fin white and with dusky-yellow base and with yellow extensions and 2-4 small orange spots that resemble egg spots (Ref. 126507). Colouration in alcohol: dorsum brown, ventral part of body silver-beige; dominant males uniformly brown; flanks with 5-7 faint vertical stripes; pectoral fins hyaline; pelvic fins hyaline in females and juveniles, dark in dominant males; dorsal, anal, and caudal fins dusky in females and juveniles; caudal fin with hyaline extensions and anal fin with 3-5 faint egg spots in dominant males; nostril, interorbital, preopercular, and lachrymal stripes and a nape band faint and ill-defined (Ref. 126507).