Ochropsora staphyleae, a new rust pathogen of Japanese bladdernut, found in central Japan

Abstract

Japanese bladdernut shrub, Staphylea bumalda (Staphyleaceae), was found infected by a fungus in Prefectures of Ibaraki and Tochigi, central Japan. The fungus produced telia beneath the host epidermis and basidiospores on metabasidia emerging from the sori on the abaxial leaf surface. Probasidia were single-celled, sessile, short-cylindrical, thin-walled, and laterally free. A four-celled metabasidium arose from a probasidium by apical elongation. Apparent biotrophic nature and the basidium morphology of the Staphylea fungus suggested its taxonomic affinity to the rust genus Ochropsora. Molecular phylogenetic analyses of D1/D2 region of LSU rDNA showed that two collections of the fungus were grouped with Ochropsora ariae (type species of the genus) and O. nambuana but formed an independent clade. The fungus under consideration was, therefore, classified in Ochropsora, and a new name, O. staphyleae, was proposed for it.