cercosporoid fungi ( Mycosphaerellaceae ) 1 .

Cercosporoid fungi (former Cercospora s. lat.) represent one of the largest groups of hyphomycetes belonging to the Mycosphaerellaceae (Ascomycota). They include asexual morphs, asexual holomorphs or species with mycosphaerella-like sexual morphs. Most of them are leaf-spotting plant pathogens with special phytopathological relevance. The only monograph of Cercospora s. lat., published by Chupp (1954), is badly in need of revision. However, the treatment of this huge group of fungi can only be accomplished stepwise on the basis of treatments of cercosporoid fungi on particular host plant families. The present first part of this series comprises an introduction, a survey on currently recognised cercosporoid genera, a key to the genera concerned, a discussion of taxonomically relevant characters, and descriptions and illustrations of cercosporoid species on other fungi (mycophylic taxa), Pteridophyta and Gymnospermae, arranged in alphabetical order under the particular cercosporoid genera, which are supplemented by keys to the species concerned. The following taxonomic novelties are introduced: Passalora austroplenckiae comb. nov., P. backmanii comb. nov., P. condensata comb. nov., P. gymnocladi comb. nov., P. thalictri comb. nov., Pseudocercospora davalliicola sp. nov., P. chamaecyparidis comb. nov., P. cratevicola nom. nov., P. gleicheniae comb. nov., P. lygodiicola sp. nov., P. lygodiigena nom. nov., P. nephrolepidigena sp. nov., P. paraexosporioides sp. nov., P. pini-densiflorae var. montantiana comb. et stat. nov., P. pteridigena sp. nov., P. ptisanae sp. nov., P. sciadopityos sp. nov., P. subramanianii nom. nov., P. thujina comb. nov., and Zasmidium australiense