THE LATE OLIGOCENE MOLLUSCAN FAUNA FROM OTRANTO (APULIA, SOUTHERN ITALY): AN EXAMPLE OF ALTERNATING FRESHWATER, LAGOONAL AND EMERGED ENVIRONMENTS

Eighteen gastropod and five bivalve species are taxonomically described from an Upper Oligocene succession cropping out near Otranto (southern Salento, Apulia, Italy). Among these, Tectarius (Echininus) japigiae, Hydrobia dubuissoni hydruntina, Pseudamnicola messapica, Pseudamnicola palmariggii and Stenothyrella salentina are new taxa. Nonmarine and lagoonal environments characterize almost the whole succession, as testified by species-poor assemblages rich in specimens of freshwater and oligo- to mesohaline prosobranchs, such as Neritinidae, Hydrobiidae, Stenothyridae, Thiaridae, Potamididae, Batillariidae, pulmonates, including Planorbidae and bivalves comprising Dreissenidae and Cyrenidae. The genera Theodoxus, Hydrobia, Melanoides, Potamides, Terebralia, Batillaria, Granulolabium, Mytilopsis and Polymesoda alternately dominate. Littoral marine elements, such as Tectarius, Turritella, Barbatia, Anadara and Chama, are scattered present in the succession, but some prevail towards the top. The fauna is palaeobiogeographically significant having strong affinities with those of the Oligo-Miocene basins of Aquitaine, Mainz, Bavaria, North Alpine Foreland, Vienna, Greece and Turkey. The analysed Otranto succession is assigned to the Chattian Galatone Formation of southernmost Apulia (Salento) based on lithological evidence and supported by the palaeontological data.