Imagines, nymphs and eggs of Rhithrogena nuragica n. sp. are described from Gennargentu, Sardinia. Nymphs and eggsof R. insularis Esb.-Pet. and R. eatoni Esb.-Pet. from Corsica are described for the first time. R. nuragica and R. insularisbelong to the same species group, namely the insularis group, characterized mainly by the very peculiar tubercules onthe egg chorion. Nymphs of this group have crenulated gills, femora with a median dark spot and plica on the first gillsubtriangular, with a digitiform projection on the free corner. R. eatoni belongs to the alpestris group.