摘要：During a survey of powdery mildews in northern Thailand, two morphologically unique powdery mildews were collected on Castanopsis and Lithocarpus . Both powdery mildews have a thin, single layer of peridium cells of chasmothecia, which is a morphological character of the genus Brasiliomyces . However, recent molecular phylogenetic analyses indicates that Brasiliomyces is polyphyletic and shows that the two powdery mildews from Thailand belong to the Erysiphe lineage with Oidium subgenus Pseudoidium anamorphs. Therefore, they are described as Erysiphe monoperidiata sp. nov. and E. asiatica sp. nov.
