Morphology Data of Petrochromis horii
Identification keys
Main Ref. Takahashi, T. and S. Koblmüller, 2014
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance males alike females
Different colors

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral fusiform / normal
Cross section
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth terminal
Type of scales

Diagnosis: Petrochromis horii differs from its congeners with no overlaps in several morphological characters: its body is deeper than that of Petrochromis macrognathus; the caudal peduncle is deeper than that of P. orthognathus; the pectoral fin is longer than that of P. macrognathus; the pelvic fin is longer than that of P. fasciolatus; the caudal fin is longer than that of P. famula, P. fasciolatus and P. orthognathus; the interorbital region is wider than that of P. macrognathus and P. orthognathus; the upper jaw protrudes more than that of P. fasciolatus and less than that of P. macrognathus, P. polyodon and P. trewavasae; the soft rays in the dorsal fin are fewer than in P. macrognathus; and the number of scales in longitudinal line is larger than in P. famula and P. orthognathus (Ref. 95531).

Description: Body short, deepest at dorsal-fin origin, gradually becoming shallow to caudal peduncle; caudal peduncle short, depth of caudal peduncle 82.2-101.6% of its length (Ref. 95531). Dorsal profile of head sloping steeply; ventral profile slightly rounded (Ref. 95531). Eye small, rounded; eye-length 62.2-72.8% of snout length; interorbital region convex (Ref. 95531). Mouth lower than body axis; jaws almost equal anteriorly; posterior edge of mouth not reaching vertical line through anterior margin of eye (Ref. 95531). Oral teeth tricuspid, arranged in 9 to 11 irregular rows at anterior parts of upper and lower jaws, making brush-like, broad tooth plate on each jaw; outer and inner teeth indistinguishable in size, shape, or arrangement pattern (Ref. 95531). Gill rakers short (Ref. 95531). Lower pharyngeal jaw sub-triangular with concave lateral margins and roundly convex caudal margins on both sides; teeth villiform (Ref. 95531). Dorsal fin originating slightly anterior to vertical line through posterior margin of operculum; each spine with a lappet near tip; all soft rays branched; posterior tip of the fin elongate, extending beyond caudal-fin base when depressed (Ref. 95531). Anal fin originating slightly anterior to vertical line through base of last dorsal-fin spine; three spines increasing in length posteriorly; first and second spines with a lappet near tip; all soft rays branched; posterior tip elongate, extending beyond caudal-fin base when depressed (Ref. 95531). Upper end of pectoral-fin base slightly posterior to vertical line through posterior margin of operculum; distal tip acutely pointed; fifth soft ray from upper longest, reaching vertical line through anus; soft rays branched, except uppermost two and lowermost two (Ref. 95531). Pelvic fin originating posterior to vertical line through posterior margin of operculum; all soft rays branched; outer soft rays longer than inner ones; outermost soft ray filamentous, reaching anal-fin origin (Ref. 95531). Caudal fin lunate; distal tips of upper and lower lobes acutely pointed (Ref. 95531). Scales on flank cycloid or ctenoid with radially directed short ctenii; granulation extending over almost entire exposed part of scale; posterior half of cheek scaled; caudal fin with scales on fin membrane between rays; other fins lack scales; upper lateral line originating from sensory canal of supracleithrum, running below dorsal margin of body, posteriorly not reaching posterior end of dorsal-fin base; lower lateral line running on body axis, anteriorly not reaching vertical line through anal-fin origin, posteriorly extending beyond caudal-fin base (Ref. 95531).

Colouration: A part of head anterior to the posterior margin of eye moss green; pale ventrally; body with eleven moss green vertical bands from nape to caudal-fin base, and a moss green or dark green horizontal broad band on body axis; spaces between the bands and ventral part of body pale green (Ref. 95531). Fins moss green; anterior margin of pelvic fin pale green (Ref. 95531). The vertical and horizontal bands are unclear in fixed specimens (Ref. 95531).

Ease of Identification

Meristic characteristics of Petrochromis horii

Lateral Lines Interrupted: No
Scales on lateral line 34 - 35
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb
total 11 - 13


Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   
Spines total 18 - 19
Soft-rays total 9 - 10
Adipose fin absent

Caudal fin

Attributes more or less truncate; more or less normal

Anal fin(s)

Fins number 1
Spines total 3 - 3
Soft-rays total 7 - 8

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   15 - 16
Pelvics Attributes  more or less normal
Position    thoracic  behind origin of D1
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Boden, Gert
Modified by Boden, Gert
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