| Diagnosis: |
Dorsal spines (total): 14-16; Dorsal soft rays (total): 9-10; Anal spines: 3-3; Anal soft rays: 7-8. Diagnosis: Parananochromis orsorum is distinguished from P. brevirostris, P. elobatus and P. ornatus by the presence of 4 tubular infraorbital bones vs. 3; from P. brevirostris and P. elobatus by the presence of scales on the chest vs. absence, and a well developed pharyngeal pad vs. weakly developed; and from P. axelrodi by a shallower body depth, being 27,3-33,7% of standard length vs. 35,6-42,2% (Ref. 97361). It differs from Parananochromis caudifasciatus by a greater preorbital distance, 19-28% of head length vs. 17-19; absence of dots on caudal fin of females vs. rows of dots in females; and more pointed snout (Ref. 97361). It differs from Parananochromis gabonicus by fewer rows in both jaws, 2 rows in both jaws vs. 2-4 in upper jaw and 2-3 in lower jaw; and in colouration, intense and regular rows of pale blue spots in soft dorsal, caudal and soft anal fins of males, yellow colouration of distal part of anal fin of both sexes, black colouration of tip of pelvic fin of females vs. rows of spots in fins absent or pale and restricted to proximal parts of fins, distal part of anal fin clear, tip of pelvic fin clear to pale white in P. gabonicus (Ref. 97361). It differs from Parananochromis longirostris by the absence of the following features in P. orsorum: silver centers on body scales in both sexes, red colouration across dorsal portion of eye, spots in dorsal, caudal and anal fins of females; and a smaller size (Ref. 97361).
Description: A medium sized, moderately elongate cichlid (Ref. 97361). Snout moderately acute (Ref. 97361). Infraorbital bone series consisting of lachrymal and four tubular elements; small gap between third infraorbital and dermosphenotic; lachrymal portion of infraorbital sensory canal with four openings (Ref. 97361). Premaxilla and dentary usually with 2 rows of acutely cusped, unicuspid teeth; outer row teeth slightly larger than those of inner rows (Ref. 97361). Lower pharyngeal bone narrowly triangular, with numerous, slender, shouldered unicuspid teeth on lateral parts of bone and larger, asymmetric bicuspid teeth in central field (Ref. 97361). First gill arch with 7-9 tuberculate gill rakers on ceratobranchial and 4-6 pointed gill rakers on epibranchial; well-developed hanging pad on pharynx roof (Ref. 97361). Scales cycloid: 17-20 upper lateral-line scales; 5-9 lower lateral-line scales; 12 circumpeduncular scales; cheek with 2-4 scale rows; 3-4 horizontal scale rows on opercle; dark unscaled spot on outer edge of opercle; chest scales very small and deeply embedded; 5-7 scales between pectoral- and pelvic-fin insertions; upper lateral line separated from dorsal-fin base at highest point by 1-2 scales, on last pored scale by 0-1 scales; posteriormost point of upper lateral line not overlapping lower; basal quarter to third of caudal fin covered with scales; other fins unscaled (Ref. 97361).
Colouration: In life, adult base body colouration grayish to brownish, darker dorsally than ventrally; dark spot on outer edge of opercle; dark margins around body scales, prominent in males and restricted to dorsal half of body in females (Ref. 97361). Colouration of fins always more intense in males; dorsal fin and dorsal edge of caudal fin with thin red margin, preceded by white or offwhite submargin; pelvic fins with white anterior edge, black colouration between first and second ray, and remainder of fin yellowish in males, rosy in females; pectoral fins clear to pale yellowish (Ref. 97361). A black midlateral band visible in some behavioural situations, passing from forehead through eye and extending onto base of caudal fin; lachrymal stripe well developed; midlateral band occasionally absent, rarely fragmented to series of black dots, with first dot immediately behind eye, 6-7 dots on body and last dot on base of caudal fin; dark band on uppermost part of dorsum sometimes visible, but often absent completely or rarely fragmented to 6-8 unregular dark blotches (Ref. 97361). Upper edge of eye yellow; lips graybrown to pale yellow (Ref. 97361). Male specific colouration: anterior portion of dorsal fin yellowish, fin membranes of soft dorsal fin parts dark reddish with some rows of pale blue spots; lower edge of caudal fin with pale yellow colouration; rest of fin with 9-11 rows of pale blue spots; some males with few small black dots on upper edge of soft dorsal and upper edge of caudal; outer parts of anal fin yellowish, rest of fin reddish; posterior parts of anal fin with 8-9 rows of pale blue spots (Ref. 97361). Female specific colouration: spiny dorsal and anteriormost portion of fin with iridescent silvery to rosy colouration, other parts of fin clear; central portion of caudal fin clear to pale reddish; anal fin yellowish to clear; pelvic fins with black tips; belly of ripe females dark rosy to violet (Ref. 97361). Juveniles of both sexes: body brown with two rows of irregular dark spots in specimens up to 10-12mm standard length; adult colouration appearing with increasing size (Ref. 97361). In preserved specimens, head and body brown to reddish brown, with dorsal half darker than ventral; black midlateral stripe, continuous from eye to base of caudal fin, sometimes fragmented as 7-8 well-defined black dots (Ref. 97361). Unpaired fins reddish brown; soft dorsal and anal fin and caudal fin with rows of black spots in males (Ref. 97361). |