Ostracods. In: ANTONIOLI, F. & VAI, G.B. (Eds.), “Explanatory notes to the litho- palaeoenvironmental maps of Italy during the last two climatic extremes: Map. 1 – Last Glacial Maximum; Map. 2 – Holocene climatic optimum, 1:1.000.000 scale

Ostracodes are aquatic, mainly benthonic microcrustaceans, widespread at all latitudes, which inhabit marine, brackish and freshwater environments. They are very sensitive to environmental parameters such as temperature, salinity, depth, substrate, pH, nutrient and oxygen content, thus they proved through time to be a valuable tool for the palaeoenvironmental and palaeoclimatic reconstructions. Thank to their different reproduction strategies, many ostracodes are capable to colonize wide geographical areas. Several species, particularly freshwater forms, are characterised by resting eggs which are desiccation-resistant or freeze-resistant, thus tolerate even long periods of adverse environmental conditions and can be passively transported by aquatic birds, amphibians or insects. Some species are parthenogenetic, other, even if amphigonic, carry out brood care inside the female shell and, in this way, their passive dispersal is more successful. Consequently, freshwater ostracodes are potentially a useful group inside which it would be possible to recognize “northern” or “southern” guests whose geographical distribution is shifted latitudinally during climate changes.