New reports of paratethyan ostracods affinity from the mediterranean basin (Sicily, Italy)

Abstract

During the late Messinian post evaporitic phase, in the eastern region between the Alps and the Aral Sea, the Paratethys was reduced to a number of large independent basins (Pannonian Basin, Pontic Basin and Caspian-Aral Basin) separated by vast continental regions. At the same time, in the Paleomediterranean region, discontinuous shallow-water basins were formed on the existing substrate. In these basins predominantly siliciclastic sediments were deposited consisting of gravels, sands, marls and silts, and containing continental oligohaline faunas. These sedimentary facies, which are largely exposed in Italy and in other Mediterranean regions, are called "Lago-Mare". These sediments overlapping the Messinian evaporitic layers in apparent conformity have already been reported from western Sicily. Now they have been sampled and analyzed in five different localities in eastern Sicily. These sedimentary facies are called "Congeria" strata (marl containing oligohaline faunas) and "Arenazzolo" (reddish arkosic sands containing brackish or freshwater ostracods). From these levels, which correspond to two different sedimentation environments, an oligotypic ostracod fauna was extracted consisting of species belonging to the genera Tyrrhenocythere, Loxoconcha and Cyprideis. Among them, Loxoconcha muelleri (Mehes, 1908) and Cyprideis anlavauxensis Carbonnel, 1979, are reported for the first time from Sicily. Two other species are new to science; one is described as Tyrrhenocythere pulcherrima sp. nov. herein, whereas, the other one is left in open nomenclature as Loxoconcha n. sp.