Shell thin, fragile, equivalve, inequilateral, moderately inflated. Outline, subovate, with beaks in front of the midline. Posterior area more expanded than anterior. Sculpture of fine concentric lines giving the shell a smooth texture. Hinge with two prominent teeth in each valve, median tooth bifid. Ligament on a shallow nymph (resilium) which is steeply inclined posteriorly. Internal margin smooth. Juvenile specimens are difficult to identify because of the complexity of the genus that is confusing.
common size :
up to 10 mm, Israel findings 7-10 mm.
Similar to the Mediterranean species Diplodonta rotundata with which it has been erroneously confused (Sabelli et al., 1990-92) and from which it differs by its smaller size, its more rounded profile, and the globose shape in adult specimens (Bogi and Galil, 1999). According to Oliver (1992), the Red Sea specimens assigned as Diplodonta sp. may be juveniles of D. subrotundata, but their even sculpture, moderate tumidity, steeply inclined resilium and thickness suggest that this is not so.
BIOLOGY / ECOLOGY
Infaunal siphonate, actively mobile, unattached animals known as suspension feeders (Todd, 2002). Another species of the family Diplodonta punctata was observed in aquaria to build a "nest" of sand grains cemented by mucus (Domaneschi, 1979).
sands, offshore; the Mediterranean records from depths 9-30 m.