Parvicardium exiguum
Habitat: it lives into detrital-muddy sediments in the infralittoral zone. It is often found either in a prelagoon habitat or in a habitat at reduced salinity.
Distribution: it is collected all over the Mediterranean. Never common. It is found in the Black Sea too.
Notes: shell solid, equivalve, inequilateral, valves trapezoidal in outline. From umbo carina reaches posterior margin which is truncated. Sculpture made by about 20 radial ribs, not much strong, alternate with fine interspaces adorned by concentric striae making dimples tiny and deep. On ribs there are rare tubercles more evident in lateral areas. Colour pattern (more evident in the internal part) is really variable: from yellow-brown to either green or reddish in colour, sometimes with irregular spots brown in colour. Internal bright, margin crenulated, periostracum pale brown in colour. This species is variable in its form and colour so that in literature there are synonyms and varieties without specific importance tied to geographical and environmental distribution. Its outline, with typical carina, makes it easy to be recognized from its similar ones even in juvenile stages. Average measures of adult specimens around 10-12 mm in length.