The new species Opegrapha subdictyospora is described from NE Brazil. It is only the third species in the genus with (sub)muriform ascospores and is further characterized by the brown pruinose discs. It was collected at Vale do Catimbau National Park in Pernambuco, which is a Caatinga area, where it is locally common. Key words: Caatinga; Dictyographa ; Lecanographa ; lichen; new species; Pernambuco; Roccellaceae ; taxonomy.