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

The poorly known bivalve Limopsis tenuis Seguenza, 1876 is redescribed from the type locality, the Messina Strait. The studied material consists of valves from sandy-gravelly bottoms in 188–319 m and from Pleistocene coarse deep-sea beds near Messina. L. tenuis is the smallest living European limopsid (maximum size c. 2.5 mm), although the Pleistocene valves are markedly larger (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 species is notably close in morphology and ecology to Limopsis angusta Jeffreys, 1879, which is also reported from the Pleistocene of Southern Italy.