Species-poor assemblages rich in specimens of non-marine to brackish molluscs occur in Oligocene stratigraphical successions, widely exposed in the Salento region (southernmost Apulia, Italy). Two new extinct oligohaline gastropods of the family Hydrobiidae (Caenogastropoda), Hydrobia (s.l.) galatoniana n. sp. and Hydrobia (s.l.) ionica n. sp., are described from the type-section of a richly fossiliferous transitional succession, the Late Oligocene (Chattian) Galatone Fm, cropping out in the Lecce district. This lithostratigraphical unit records foraminiferal, molluscan and ostracod assemblages indicative of alternating oligohaline to shallow water lagoonal and littoral marine conditions. At some silty levels of the investigated succession, the two new species occur in dense populations forming shell-beds in oligotypical assemblages, accompanied by smooth-shelled ostracods. An oligohaline environment is proposed for these assemblages. This paper represents a contribution to the knowledge of Oligocene hydrobiids from Italy, where their record is extremely scarce and poorly known.
Chattian, Gastropoda, Hydrobiidae, oligohaline palaeoenvironment, new species