Morphology data of Amusium japonicum
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 thin, medium to large sized (commonly exceeding to 10 cm in length), laterally compressed, almost circular in outline, gaping anteriorly and posteriorly. Both valves somewhat convex, the right (lower) valve only a little more inflated and larger than the left (upper) valve. Ears small, subequal in size and shape, with the right anterior ear faintly sinuated at anteroventral margin and devoid of ctenolium. Surface of left valve with 2 broad and very shallow depressed areas radiating from the umbo to anteroventral and radial lines. Interior of both valves with distinct radial ribs, usually in pairs, much narrower than the flat interspaces and becoming obsolete on umbonal area. Right valve with 42 to 54 internal radial ribs (46 to 54 in the typical subspecies A. japonicum, and 42 to 48 in the southern A. japonicum balloti). Colour: outside of left valve reddish brown, with variable shades along the concentric growth marks; outer colour pattern of subspecies balloti also with small, yellowish and dark brown spots along radial lines on umbonal area and often with a few irregular, larger dark spots towards periphery. Interior of left valve glossy to pale yellow externally and internally; subspecies balloti with an additional external brown scattering along some concentric growth marks.
Ease of Identification

Meristic characteristics of Amusium japonicum

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   
Ref. [ e.g. 3742]
Glossary [ e.g. cnidaria]
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