Morphology Data of Hippopotamyrus longilateralis
Identification keys
Main Ref. Kramer, B. and E.R. Swartz, 2010
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
Cross section compressed
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth
Type of scales cycloid scales

Diagnosis: Hippopotamyrus longilateralis can be distinguished by following characters: distance from dorsal fin origin to end of caudal peduncle 37.9-41.7% of standard length; predorsal length 61.2-64.9% of standard length; distance from tip of snout to anal fin origin 59.0-62.7% of standard length; caudal peduncle length 19.5-22.0% of standard length; head length 19.2-22.8% of standard length; snout length 45.7-54.8% of head length; body depth 20.3-24.5% of standard length; number of dorsal fin rays 18-21; number of anal fin rays 22-25; number of scales in a linear series along the lateral line row 74-80; number of scales around caudal peduncle 19-22; and bipolar, pentaphasic waveform of EOD pulse (Ref. 85059).

Description Head broadly rounded with a terminally positioned mouth, lower jaw protruding less forward than upper; body long and slender, laterally compressed (Ref. 85059). Dorsal fin origin set far back and behind that of anal fin, situated about two-thirds of standard length from snout, obliquely orientated with anterior portion of the fin higher than the posterior portion; number of dorsal fin rays 18-21; anal fin opposite dorsal fin but origin further anterior and also obliquely orientated, anteriorly lower and posteriorly higher, margin broadly rounded; number of anal fin rays 22-25 (Ref. 85059). Scales cycloid with reticulate striae, except in centre, extending anteriorly to operculum and pectoral fins; scales around caudal peduncle 19-22 (Ref. 85059). Caudal peduncle slender and subcylindrical over the entire length, usually slightly less than one-fifth in standard length; tail fin with broadly rounded lobes (Ref. 85059). EOD bipolar and pentaphasic, duration of the two main phases about 230 ┬Ás but whole pulse may last up to 5 milliseconds because of weak pre- and post-potentials (Ref. 85059).

Colouration: Dark brown with a vertical black band from dorsal origin that is only weak in most specimens (Ref. 85059). Colour in preservation dark to medium brown, often with milky-grey hue, especially where opaque 'mormyrid skin' is present (Ref. 85059).

Ease of Identification

Meristic characteristics of Hippopotamyrus longilateralis

Lateral Lines Interrupted: No
Scales on lateral line 74 - 80
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle 19 - 22
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 18 - 21
Adipose fin absent

Caudal fin

Attributes forked; more or less normal

Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 22 - 25

Paired fins

Pectoral Attributes  more or less normal
Pelvics Attributes  more or less normal
Position    abdominal  before origin of D1
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