Late Miocene brackish Loxoconchidae (Crustacea, Ostracoda) from Italy.

The Family Loxoconchidae Sars 1925 includes over 800 fossil and extant species that mainly inhabit littoral and sublittoral marine environments. Only few living species (i.e. Loxoconcha elliptica Brady, Elofsonia baltica (Hirschmann), Hirschmannia viridis (Müller), Sagmatocythere pennata (Schornikov), Loxoconchissa (Loxocaspia) immodulata Schornikov) can withstand brackish waters.During Late Miocene, in the Paratethyan domain wide brackish basins developed and numerous Loxoconchidae adapted to the decreased salinity. Beside several species pertaining to the genus Loxoconcha, other species have been referred to the genera Loxocorniculina, Loxoconchissa s.s. and Loxoconchissa (Loxocaspia). In the Italian brackish basins developed during Late Miocene it is possible to recognise the presence of all these genera: Loxoconcha and Loxocorniculina are mainly documented in the latest Messinian lago-mare biofacies [i.e. Loxoconcha eichwaldi Livental, Loxoconcha muelleri (Mehés), Loxoconcha rhombovalis Pokorny and Loxocorniculina djafarovi (Sneider in Suzin)]; on the contrary Loxoconchissa s.s. and Loxoconchissa (Loxocaspia) seem to be confined to the Late Tortonian-early Messinian brackish basins of Tuscany (Volterra-Radicondoli, Cinigiano-Baccinello and Velona Basins) and are represented by new species.A re-definition of the genus Loxoconchissa s. l. on the base of the hinge and of the sexual dimorphisms is presented in this paper and its geographic and stratigraphic distribution are discussed.