More than meets the eye — unexpected diversity in downy mildews (Oomycetes) on grasses in Australia

Abstract

Eleven new downy mildew species on grasses are described from Australia based on morphology and DNA sequence analysis of the mitochondrial cox2 and/or ribosomal large subunit genes. Peronosclerospora aristidae is proposed to accommodate a downy mildew on the indigenous Australian tropical grass Aristida hygrometrica. Baobabopsis marneyi occurs on Enneapogon spp. across northern Australia. Eraphthora drenthii and E. occultata are present on Eragrostis spp. in eastern Australia. Seven new species, Peronosclerospora ischaemi on Ischaemum fragile; P. panici from a single herbarium specimen of Panicum laevinode; P. sehimatis on Sehima nervosum; P. shizachyrii on Shizachyrium fragile; and three species, P. boughtoniae, P. jamesiae, and P. mactaggartii from indigenous Australian Sorghum spp., occur in northern Australia. Other published records of downy mildews on grasses in Australia are discussed.