Morphology Data of Kneria rukwaensis
Identification keys
Main Ref. Seegers, L., 1995
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
Different colors
Remarks Females show the same color as males but juveniles are more or less uniformly greyish to brownish (Ref. 27292).

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral elongated
Cross section circular
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth sub-terminal/inferior
Type of scales

Diagnosis: dorsal fin origin behind pelvic fin origin; 96-104 lateral line scales; preanal length 70.7-76.2% SL; prepelvic length 46.7-52.6% SL; 9-11 anal fin rays (Ref. 26644). Lower lobe of caudal fin longer and narrower than upper lobe in fully adult males (Ref. 26644, 27292), the upper lobe as long as the proximal part of the caudal fin (Ref. 27292). Opercular disc of males characteristic, its posterior margin broad, and postopercular apparatus well developed and pillow-like (Ref. 26644).

Description: body slender, depth 5.1-7.3 times in standard length (SL); head short, 4.1-5.6 times in SL (Ref. 26644). Origin of dorsal fin nearer to end of snout than to base of caudal fin (Ref. 26644), in most cases clearly behind or nearly above pelvic fin origin (Ref. 26644, 27292). Pelvic fin long, 1.1-1.5 times in head length (HL); pectoral fin long, about 1.2-1.9 times in HL; snout short, about 3.1-4.0 times in HL and usually slightly longer than eye diameter, rarely shorter, about 0.8-1.1 its length; eye diameter 3.5-4.2 times in HL (Ref. 26644). Opercular organ in males present and heavily pigmented, large but shallow with a wide rim, the posterior part of the rim wider than its anterior part (Ref. 26644) and membraneous (Ref. 27292). Male postopercular organ pronounced with a series of about 24 oblique laminae, its upper part protruding, the lateral line running along the rim (Ref. 26644). Opercular organ only very rudimentary in females (Ref. 27292). Caudal peduncle long, 5.4-5.8 times in SL; scales small, numerous, difficult to count (Ref. 26644).

Coloration: in life: ground color medium grey to brown; dark greyish band runs from opercular region straight to base of caudal fin; this band darker at dorsal edge and to posterior end and may end in a large dark spot; it is slightly bluish on posterior part of body and caudal peduncle; this band is dorsally accompagnied by a narrow lighter streak which is golden to brownish and contrasts with the dark band below; area above this streak dark brownish to greyish, speckled with many faint, dark, small, greyish spots reaching the lower flanks; these spots larger on posterior part of body and caudal peduncle; midlateral band at its lower margin not sharply defined, at least in its anterior part, but progressively lighter to the belly; belly whitish, base of pelvic fins with a dark spot; opercular organ heavily pigmented; postopercular organ dark especially in its upper parts (Ref. 26644). Fins (dark) greyish (Ref. 26644) to blackish at the base (Ref. 27292), otherwise slightly greyish along the rays (Ref. 27292) and hyaline (Ref. 26644, 27292). Alcohol preserved: generally same color as life specimens; ground color light greyish-brown; dark midlateral band more distinct; in most specimens it becomes more evident that the band is composed of spots which merge together (Ref. 26644). Females show the same color as males but juveniles are more or less uniformly greyish to brownish (Ref. 27292).

Ease of Identification

Meristic characteristics of Kneria rukwaensis

Lateral Lines 1 Interrupted: No
Scales on lateral line 96 - 104
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


Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   0
Ventral  0
Spines total 0
Soft-rays total 8 - 11
Adipose fin absent

Caudal fin

Attributes forked; more or less normal

Anal fin(s)

Fins number 1
Spines total 0
Soft-rays total 9 - 11

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   15 - 16
Pelvics Attributes  more or less normal
Position    abdominal  before origin of D1
Spines     0
Soft-rays   8 - 8
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
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