Lichens from the Brazilian Amazon, with special reference to the genus Astrothelium

Preliminary results are presented of a lichen expedition to the Reserva Florestal Adolpho Ducke, a 100 km(2) conservation unity of undisturbed primary rain forest near Manaus in the Amazonas state, Brazil. So far, 157 species were identified, 122 of which are first reports from the Amazonas state, nine of which are first reports for Brazil. Most species are also found in other Amazonian states like Rondonia and Amapa. In addition, the following new species are described: Astrothelium dimidioinspersum, A. megeustomurale (also from Rondonia and Tocantins states), A. rubrostiolatum, A. valsoides, Chiodecton lichexanthonicum, Enterographa lichexanthonica, Fellhanera baeomycoides and Viridothelium ustulatum, In addition, Astrothelium astrolucidum and A. introflavidum are described from adjacent states. A high percentage of the new species has lichexanthone or another xanthone as cortical substance.