Germarostes (Haroldostes) rugiceps (Germar) and Germarostes (Haroldostes) diffundus (Petrovitz) (Ceratocanthinae) are recorded for the first time for Argentina from Misiones and Corrientes, respectively. This brings to thirteen the total number of the Ceratocanthinae species recorded for Argentina up to now. Some remarks on the type series of G. diffundus and on the collecting circumstances of the Argentine specimens in here discussed are included.