Taxonomic notes on the genus Plectocarpon (lichenicolous Ascomycetina)

The genus Plectocarpon is included in the Opegraphaceae (Opegraphales). It is distinguished by rounded mono- or multilocular, often stromatic ascomata with a reduced non-carbonized exciple, asci of the Opegrapha- typs, (1–)3(-6)-septate colourless spores with a distinct perispore and anastomosed paraphysoids. The genus includes at least 10 species, all lichenicolous on macrolichens, belonging mainly to the Peltigerales. 5 species are here described as new: P. lambinonii sp. nov. on Lobaria isidiosa and L. retigera from Papua New Guinea, Russia and Rwanda, P. macaronesiae sp. nov. on Lobaria puimonaria and L. suhlaevis from the Azores, the Canary Islands and Madeira, P. sampaianae sp. nov. on Pannaria sampaiana from Great Britain and Spain, P. scrobiculatae sp. nov. on Lobaria scrobiculata from France, Great Britain, Norway and Spain and P. usneae sp. nov. on Usnea exasperata from Rwanda. An additional undescribed species on Sticta leami from Papua New Guinea is mentioned. Most species form distinct galls on their host lichens.