Two new dematiaceous hyphomycetes on Cyathea from Mexico

Belemnospora navicularia anam. sp. nov, and Hermatomyces amphisporus anam. sp. nov., two new taxa of hyphomycetes collected on a rotten branch of Cyat hea sp. (a fern tree) in a Mexican forest are described and illustrated. B. navicularia is characterized by navicular, S-septate conidia with brown ce ntral cells and paler ends. H. amphisporus is distinguished by two kinds of conidia, the first turbinate, gray brown towards the apex and hyaline at t he lower cells and other type lenticular and black at the center as typical for the genus Hermatomyces. Keys to Belemnospora and Hermatomyces species are proposed. (C) 2000 Adac/Editions scientifiques et medicales Elsevier SA S.