Morphology Data of Petrocephalus squalostoma
Identification keys
Main Ref. Kramer, B., R. Bills, P. Skelton and M. Wink, 2012
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
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 sub-terminal/inferior
Type of scales cycloid scales

Diagnosis: Petrocephalus squalostoma is distinguished from all other Petrocephalus species of the Congo province by the following combination of characteristics: body coloration pattern without intense melanin mark, sometimes a faded subdorsal roundish mark present; short dorsal fin with 15-22 branched rays and 27-32 branched rays in the anal fin; more than 13 scale rows between the anterior base of the anal fin and the lateral line; and three distinct electroreceptive rosettes in the head (Ref. 91772). Body depth 32.9-33.5% of standard length; length of snout to posterior orbital rim of eye 40.9-44.1% of head length; predorsal length 66.7-67.3% of standard length; length of dorsal fin 16.0-17.4% of standard length; preanal length 59.8-60.3% of standard length; distance anterior base of pectoral fin to anterior base of pelvic fin 19.8-20.8% of standard length; caudal peduncle depth 34.6-38.8 of its length (Ref. 91771).

Description: Body asymmetrically oval shape with long, prominent, arched back and deep body; head broadly rounded, with very short snout to posterior orbital rim, 40.9-44.1% of head length; head length 26.3-28.0% of standard length; eye diameter 22.3-25.7% of head length; small mouth ventrally located under the eye; head and body dorsolaterally compressed (Ref. 91771). Teeth small and bicuspid, 5-13 (median 11) teeth in a single row in the upper jaw, 16-23 (median 19) teeth in a single row in the lower jaw (Ref. 91772). Dorsal fin set far back, at about two-thirds of standard length from snout, starting above the fourth or fifth ray of the anal fin; 18-21 dorsal fin rays (Ref. 91771). Predorsal length 66.7-67.3% and preanal length 59.9-60.3% of standard length (Ref. 91771). Anal fin length 24.1-25.0% of standard length, longer than and opposite dorsal fin; 29-31 anal fin rays (Ref. 91771). Slender, subcylindrical caudal peduncle, with depth 34.6-38.8% of its length; its length 18.4-19.2% of standard length (Ref. 91771). Scales extending anteriorly to operculum and pectoral fins; 39-42 scales on lateral line; 12 circumpeduncular scales (Ref. 42540, 91771).

Colour: homogeneously brown in preservation (Ref. 91771). Body background mostly silver-white/gold with metallic reflections, darker dorsally from the snout to the caudal peduncle (Ref. 91772). In a few specimens presence of a pale subdorsal roundish mark lying below the anterior base of the dorsal fin, on each side of the body (Ref. 91772). All fins whitish-yellowish, mostly translucent with fine black pigmentation on the lepidotrichia (Ref. 91772).

Ease of Identification

Meristic characteristics of Petrocephalus squalostoma

Lateral Lines Interrupted: No
Scales on lateral line 35 - 42
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle 12 - 12
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb


Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   
Spines total 0 - 0
Soft-rays total 15 - 22
Adipose fin absent

Caudal fin


Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 27 - 32

Paired fins

Pectoral Attributes  
Pelvics Attributes  
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Boden, Gert
Modified by Bailly, Nicolas
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cfm script by eagbayani, 17.10.00, php script by rolavides, 13/03/08 ,  last modified by sortiz, 06.27.17