A new diatom genus and species, Australodiscus peruvianus Porguen et Sullivan, is described from an Eocene marine deposit from the Paracas Peninsula, Peru. The valve outline is stellate with ocelli and rimoportulae situated singly on alternate points of the star. The rimoportulae are winged and situated on a secondary marginal ridge. Three types of spines are present; two of these are also winged. Our new form appears to be best placed for the present in the centric family Triceratiaceae (Schütt) Lemmermann, being most closely related to the type genus Triceratium Ehrenberg and Grovea A. Schmidt.