CystothecaCystotheca is a genus of plant pathogenic fungi in the family Erysiphaceae. Members of the genus are found on Calophyllum, Castanea, Castanopsis, Murraya and Quercus species in Asia and North America.DescriptionMany Cystotheca species form dense, white or brown, distorting patches on the leaves of their hosts. Some species in this genus are also known to cause witch's-broom galls. The distribution of this genus is limited to Asia and North America. Only Cystotheca lanestris and Cystotheca mexicana are not found in Asia.TaxonomyThe genus was once considered conspecific with Sphaerotheca, but Cystotheca is well-distinguished by the presence of special aerial hyphae and the chasmothecial wall being separated into two distinct layers. Cystotheca is phylogenetically close to Podosphaera.SpeciesThe genus comprises the following species:Cystotheca castanopsidis Cystotheca esetacea Cystotheca indica Cystotheca kusanoi Cystotheca lanestris Cystotheca mexicana Cystotheca nanyuensis Cystotheca quercina Cystotheca tjibodensis Cystotheca vignae Cystotheca wrightii ''Setoidium murrayae''