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Morphology Data of Marcusenius desertus
Identification keys
Main Ref. Kramer, L.B., F.H. van der Bank and M. Wink, 2016
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance always different morphology between mature adults
Different colors
Remarks Males approaching sexual maturity develop a kink in the base of the anal fin which is absent in juveniles and females where the anal fin base is straight (Ref. 113652).

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral elongated
Cross section compressed
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth terminal
Type of scales cycloid scales

Diagnosis: Marcusenius desertus can be distinguished from its congeners by a combination of the following characters: short snout length, 40.8-45.8% of head length; small eye diameter, 11.9-19.5% of head length; nares separation 12.7-17.6 times in head length; short preanal distance, 59.2-62.7% of standard length; short head length, 17.6-20.8% of standard length; and long anal fin, 23.7-27.4% of standard length (Ref. 113652).

Description: Head with terminal mouth well in front of eye, mental lobe on lower jaw protruding beyond upper jaw; head and body dorso-laterally compressed (Ref. 113652). Dorsal fin situated about two thirds of standard length from snout, obliquely orientated, anteriorly higher and posteriorly lower, distal margin slightly crescentic with anterior two or three rays longer than posterior rays, number of rays 21-25: anal fin opposite dorsal fin with distinctly more anterior origin, obliquely orientated, anteriorly lower and posteriorly higher, anterior rays longer than posterior ones, especially in males where they also appear stronger and often darkened, distal margin crescentic, number of rays 26-32 (Ref. 113652). Scales cycloid with reticulate striae, scales extending anteriorly to operculum and pectoral fin; number of circumpeduncular scales 11-15 (Ref. 113652). Caudal peduncle relatively deep, subcylindrical entire length, 34.5-42.6% in its length (Ref. 113652). Electric organ discharge (EOD) biphasic with pre-potential so weak it is not always noticeable; significant sex difference in EOD, with male EODs usually of longer duration and weaker N-phase amplitude and P-phase amplitude than females (Ref. 113652).

Colouration: Colour in life: brownish grey with many distinct dark-brown blotches, except on head and belly, sometimes purple hue depending on the angle of light incidence, pelvic fins light and transparent, pectorals darker (Ref. 113652). Colour in preservation: brown (Ref. 113652).

Ease of Identification

Meristic characteristics of Marcusenius desertus

Lateral Lines Interrupted: No
Scales on lateral line 55 - 62
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle 11 - 15
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 21 - 25
Adipose fin absent

Caudal fin

Attributes forked; more or less normal

Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 26 - 32

Paired fins

Pectoral Attributes  
Pelvics Attributes  
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
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