As part of an ongoing comprehensive inventory of all Galapagos lichens, the genus Parmotrema has been revised. In Galapagos this genus is represented by thirty-five species, seven described as new to science: Parmotrema cactacearum, P. erectociliatum, P. lawreyi, P. marcellianum, P. pustulotinctum, P. saxoisidiatum and P. weberi. Parmotrema weberi, although previously informally recognized by Mason E. Hale, is now formally described here, the name thus validated. Reports of four species are doubtful or incorrect. Nine species are reported from the Galapagos for the first time, seven of those being also new for Ecuador. Parmotrema cooperi, previously known only from Central America, is now also reported from South America. Detailed descriptions and illustrations are provided for all thirty-five species, together with a dichotomic key for their identification. Diagnostic differences are discussed. If all newly described species are confirmed as endemic to the archipelago, the proportion of endemism within Parmotrema appears to be similar to most other groups of lichens recently reviewed.