Preliminary data on the freshwater ostracods from the Middle-Late Pliocene Tiberino “palaeo-ancient lake” (Umbria, central Italy)

In this paper the preliminary results of the analyses on the ostracod assemblages coming from the Middle– Late Pliocene Tiberino Lake (Umbria, central Italy) are discussed. Three sections have been investigated, Cava Toppetti and Fosso Bianco, whose sediments record a deep lacustrine facies, and Dunarobba, which represents the littoral facies of the lake. Cava Toppetti and Fosso Bianco ostracod assemblages are very similar, made exclusively by Candonidae (six genera and eleven species, nine of which are new) and Limnocytherinae (one genus including one new species), while at Dunarobba the assemblages are more diversified, including Candonidae (four genera and five species), Limnocytherinae (one genus including one new species), Ilyocyprididae (one genus and three species), Cytherideinae (one genus and two species) and Cyprididae (two genera and two species, one of which is new). On the whole, the Tiberino Lake ostracod assemblages seems to be characterised by a high degree of endemism, particularly in the deep lacustrine facies (up to 83%) and, among the Candoninae, intralacustrine speciation is recognizable for genera Candona (Neglecandona), Sirmiella and “Caspiocypris”. This latter gives rise to a “species flock”. The characteristics of the collected ostracod fauna, coupled with the long duration of the lacustrine sedimentation (1.8 Ma) concur to suggest that the Middle–Late Pliocene Tiberino Lake was a “palaeo–ancient lake”.