A preliminary study of the Parmotrema species with alectoronic acid revealed a list of 63 such species worldwide. Two of these are newly described here, Parmotrema columnatum, with inflated apothecial stipes, and Parmotrema marginatihiatum, with abundant lobules, both from Brazil. A checklist with the main literature for each species and a working key are presented together with some illustrations of types or fresh collections, mainly from Brazil. Key words: Brazil, lichens, Parmelia, UV test.