Morphology data of Isognomon isognomum
Identification keys
Main Ref. Poutiers, J.M., 1998
Appearance refers to

Sex attributes

specialized organs
different appearance
different colors
remarks

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral
Cross section
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth
Diagnosis Shell relatively high and narrow in outline, with undulating commissure and strong posteroventral elongation. Shape often very irregular, due to the confined space in which the shell grows and to the effect of repair. Dorsal margin long and straight to slightly arched, more or less strongly expanded posteriorly in a wing-like ear that increases with growth and may attain a size double the length of shell. Anterior margin elongated, markedly sinuous dorsally and extending a little or not at all forward of umbones. Posterior margin concave near the posterior ear, then more or less parallel to anterior margin. Ventral margin roughly rounded. Umbones small, pointing at anterior end of dorsal margin. Outer surface with irregularly concentric lamellate processes, often encrusted with marine growths and corroded towards the umbones. Ligamental area with numerous transverse grooves (more than 20 in large specimens). Nacreous area of the inner side of shell more or less expanded ventrally, its margin often poorly defined. Colour: outside of shell bluish purple to almost black, often paler to whitish umbonally. Interior porcelaneous and similarly coloured on non-nacreous area; nacreous area much paler, with bluish purple hue.
Ease of Identification

Meristic characteristics of Isognomon isognomum

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

Fins

Dorsal fin(s)

Attributes
Fins number
Finlets No. Dorsal   
Ventral  
Spines total
Soft-rays total
Adipose fin

Caudal fin

Attributes

Anal fin(s)

Fins number
Spines total
Soft-rays total

Paired fins

Pectoral Attributes  
spines     
soft-rays   
Pelvics Attributes  
Position    
spines     
soft-rays   
Main Ref. (e.g. 9948)
Glossary (e.g. cnidaria)
Comments & Corrections
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