Taxonomy of the Phakopsora ampelopsidis species complex on vitaceous hosts in Asia including a new species, P. euvitis

Abstract

A grape leaf rust fungus, Phakopsora ampelopsidis, distributed in Japan consisted of three populations differing in their life cycle and host specificity. One population forms the uredinial and telial stage on Ampelopsis, another population on Parthenocissus, and a third population on Vitis. The three populations were well circumscribed by morphological characteristics: number and distribution of urediniospore germ pores, shape and size of uredinial paraphyses, arrangement of teliospores in the sorus, shape and size of basidiospores, and apical wall thickness of aeciospores. Consequently, the three fungal populations were distinct species. The population on Ampelopsis is P. ampelopsidis sensu Dietel & P. Sydow and the population on Parthenocissus is P. vitis sensu P. Sydow. A new name, P. euvitis, is proposed for the species that embraces the population on Vitis in Japan. Herbarium specimens from Asia previously identified as P. ampelopsidis were morphologically identified as the three species that corresponded with the host differences. Although only P. euvitis causes leaf rust of cultivated grapes in Asia, this species and an additional species, P. uva, are involved in the grape leaf rust in the Americas.

Key Words:

• Ampelopsis
• host specificity
• Meliosma
• Parthenocissus
• rust
• Uredinales
• Vitaceae
• Vitis