Peronosclerospora Species and Other Downy Mildews of the Gramineae

SUMMARY

The subgenus Peronosclerospora of Sclerospora is raised to generic rank and described, The following species are transferred from Sclerospora into Peronosclerospora: S. dichanthiicola, S. maydis, S. miscanthi, S. philippinensis, S. sacchari, S. spontanea, S. sorghi, and S. westonii. Peronosclerospora sacchari is the type species of the genus. The diagnostic characters distinguishing Peronosclerospora and Sclerospora are the production of true conidia which always germinate by a germ tube in Peronosclerospora, and the production of typical sporangia with a modified apical area which functions as an operculum through which zoospores escape in Sclerospora. The phylogeny of the Peronosporales is also discussed.