Limopsis tenuis Seguenza, 1876, a poorly known Mediterranean bivalve (Arcoida, Limopsidae)

The poorly known bivalve Limopsis tenuis Sequenza, 1876 is redescribed from the type locality, the Messina Strait. The studied material consists of va lves from sandy-gravelly bottoms in 188-319 m and from Pleistocene coarse d eep-sea beds near Messina. L. tenuis is the smallest living European limops id (maximum size c. 2.5 mm), although the Pleistocene valves are markedly l arger (up to c. 5 mm). It is the sole Mediterranean limopsid known from an area (the Messina Strait) far from the influence by Atlantic waters. The sp ecies is notably close in morphology and ecology to Limopsis angusta Jeffre ys, 1879, which is also reported from the Pleistocene of Southern Italy.