Cladosporium is a form genus comprising phylogenetically unrelated groups of fungi among which there are human as well as plant pathogens, post harvest pathogens, taxa with strong indoor relevance, and saprotrophs. Several of the Cladosporium species sporulate by dry blastoconidia and are among the commonest air-borne fungi known. Cladosporium sensu stricto is linked to a Davidiella (Mycosphaerellaceae) teleomorph. However, because of the rather simple characters found in the Mycosphaerellaceae, this family is broadly defined and comprises anamorphs of numerous other hyphomycete genera, many of which are of economic importance. The following research topics will be focused upon: (1) Using sequences of the rDNA Large Subunit Cladosporium sensu stricto will be delineated phylogenetically. (2) Selected Cladosporium species not belonging to the core group will be characterized and phylogenetically elucidated (e.g. Cladosporium musae, a pathogen on banana and C. cubispora, a species with an extraordinary conidiogenesis). (3) Using multi-allelic sequences data, Cladosporium herbarum, C. cladosporioides, and C. epiphyllum, which very likely present insufficiently resolved species complexes, will be studied, and the various species described. (4) Using these phylogenetic characters and by describing the mating type system found in the phylogenetic species, the degree of sexual recombination within these potentially widely distributed air-borne fungi will be determined. (5) By phylogenetic identifications of strains collected in different, contrasting climates, particularly in the indoor environment and from plant products, the climatic effect on the species distribution and biogeography of the mainly air-borne taxa will be studied.