Specimens of green frogs from Southern France belonging to the species Rana (Pelophylax) perezi Seoane, 1885 and to its associated klepton were identified by enzyme electrophoresis. These specimens, as well as specimens of Rana (Pelophylax) ridibunda Pallas, 1771 from Poland, were submitted to a morphometrical analysis, which allowed to find diagnostic measurements and ratios for the three taxons. These allow to confirm the identification of the lectotypes of Rana fortis Boulenger, 1884 (currently considered a subjective synonym of Rana ridibunda, but which might prove to be a distinct taxon) and of Rana esculenta perezi. Both these lectotypes are redescribed. A Latin scientific name and a description are also provided for the klepton associated in Southern France and north-eastern Spain with Rana perezi, and which was until now known as "Graf's frog" or "Rana kl. RP".