Crustacea Ostracoda

The class Ostracoda is made up of small crustaceans, with a shell size generally ranging from 0.2 to 30 mm, living in a wide variety of aquatic environment, from deep-sea waters to the proximity of hydrothermal springs. A small number of species has been recorded in damp terrestrial environments. The majority of the taxa have a wholly benthic lifestyle, but ostracods are also well represented in the pelagic fauna. Recent species presently described are about 8.000, and the number of living species is probably around 20.000. Ostracods have a low-Mg bivalve carapace showing a high preservation potential both in subrecent and in ancient sediments. Consequently many species have been described exclusively on the basis of the shell features and the known fossil species, approximately 25.000, largely surpass the Recent ones (Horne et al., 2002). In the Italian seas both the living subclasses - Myodocopa and Podocopa - occur. Subclass Myodocopa includes the orders Myodocopida and Halocyprida; the subclass Podocopa comprises orders Platycopida and Podocopida, while Paleocopida, frequently recorded in Paleozoic sediments and represented by few living species, seem to lack in Mediterranean waters. A critical reviewing of available literature data allowed to recognize as living in Italian waters 377 ostracod species, pertaining to 102 genera. It has to be noted that distribution data are quite heterogeneous among different areas. The Adriatic (zones 7-9) ostracofaunas, studied in a series of wide investigations by authors (Ascoli, 1964; Masoli, 1968, 1969; Bonaduce et al., 1974, 1976; Breman, 1975, 1976a, 1976b; Montenegro and Pugliese, 1996) are the best known of the Mediterranean. Beginning from the G.W. Müller's monograph on the ostracods of the Gulf of Naples (1894), a cornerstone of the modern ostracodology, several papers (Puri, 1963; Puri et al., 1964; 1969; Bonaduce, 1965; Bonaduce and Gervasio, 1966; Melis and Pugliese, 1985; McKenzie and Bonaduce, 1993; Arbulla et al., 2001, 2004; Bonaduce and McKenzie, 2004) considered different areas of the Tyrrhenian Sea (zones 2-3) describing a number of new species and furnishing their distribution and ecological preferences. Even if data regarding the remaining part of the Italian Seas are less complete some areas, especially the Gulf of Taranto, have been studied in detail (Puri et al., 1969; Bonaduce and Pugliese, 1979; Bonaduce et al., 1982b, 1983, 1985; Peypouquet and Nachite, 1984; Bonaduce and Mascellaro, 1985; Malz and Jellinek, 1994; Aiello et al. 2006). Studies concerning the taxonomy and ecology of a small number of taxa report the occurrence of many ostracod species in Italian waters, providing scattered but noteworthy data (Decima, 1964; Puri and Dickau, 1969; Sissingh, 1975; Athersuch, 1976, 1977, 1978a, 1978b, 1978c, 1978d, 1979a, 1979b, 1980a, 1980b, 1981, 1982; Minichelli et al., 1976; Pugliese et al., 1976; Bonaduce et al. 1976b, 1977, 1980; 1982a, 1998, 1999; Breman, 1978; Athersuch and Whittaker, 1982, 1987a, 1987b; Bonaduce and Danielopol, 1988; Danielopol and Bonaduce, 1990; Danielopol et al., 1995; Aiello and Barra, 2001a, Aiello et al., 2001; Mostafawi, 2002). Furthermore, due to the high paleontological value of the ostracod shell, studies which afford primarily the study of fossil specimens, furnish distribution data on Recent species (Ruggieri, 1959, 1975, 1976; Bonaduce et al., 1986, Abate et al., 1993, 1994; Aiello et al., 1993, 1996a, 1996b, 1996c, 2000; Barra et al., 1996; Barra and Bonaduce, 1996, 2000; Aiello and Barra, 2001b; Aiello and Szczechura, 2001). We have to underline that, although the relatively large amount of data, the knowledge of Italian ostracods is still incomplete. Detailed studies on Mediterranean areas such as the Aegean Sea (e.g. Barbeito-Gonzalez, 1971; Stambolidis, 1985) and North African waters (e.g. Yassini, 1979; Bonaduce et al. 1988; 1996; Lachenal, 1989) evidenced that many taxa are still undescribed or unrecorded in Italian waters. Considering the vicinity of these areas and (especially for the Greek waters) the similarity of ecological conditions, it can be expected that new investigations are needed to define exhaustively the distribution and taxonomy of the ostracods of the Italian seas.