Cystotheca kusanoi comb. nov.: a redescription with new morphological observations

Abstract

Conspecific Korean and Japanese powdery mildew specimens (including the type of Sphaerotheca kusanoi) on Quercus spp. previously identified as Cystotheca lanestris have been revealed as morphologically and phylogenetically distinct from North American C. lanestris specimens. The Asian specimens are confirmed as a separate species under the new combination Cystotheca kusanoi. Cystotheca kusanoi lacks distinct fibrosin bodies, even in fresh conidia and conidiophores. A key to Cystotheca spp. is provided.