Detailed stratigraphical and paleobiological studies on the Mesozoic carbonate platform of eastern Sardinia (Italy) revealed the occurrence of an unknown foraminifer in the Bathonian (Middle Jurassic) Dorgali Dolostone cropping out in the Posada hill. Posadia feroniensis n. gen., n. sp., a new distinctive agglutinated foraminifer referable to the family Hormosinidae Haeckel, 1894, is formally described and figured. Posadia is morphologically characterized by an uniserial, roughly finished test with inverted ''V''-like chambers in longitudinal section.