XVI International Botanical Congess

The lobate thallus, special ecological requirements and patterns of secondary metabolites are important characters of the species in the Buellia epigaea-group. Depsides and depsidones are the main substances in species of the Northern Hemisphere, xanthones are common in the Australian representatives, which have been studied for the first time. The latter apparently constitute a separate complex with filiform conidia as an additional character, representatives occur on calcareous substrates in Western and South Australia, New South Wales, the Australian Capital Territory and Victoria. Their position within the large and heterogenous genus Buellia is discussed. Buellia asterella is critically endangered because of a rapid decline of suitable habitats. B. zoharyi is newly reported from the Canary Islands (Lanzarote) and from Crete.