Kuehneola japonica and K. warburgiana are the only species of genus Kuehneola that parasitize plants belonging to genus Rosa (Rosaceae). Systematic revision of the genus Phragmidium and related genera by molecular phylogenetic analyses using nuc rDNA internal transcribed spacer (5.8S-ITS2 = ITS2) and nuc rDNA 28S (28S) sequences indicated that K. japonica and K. warburgiana belong to a group of Phragmidium species that also occur on Rosa. Morphological and molecular phylogenetic analyses revealed that these Kuehneola species were transferred to Phragmidium and renamed as P. japonicum and P. warburgianum. Two new Phragmidium species were also discovered on Rosa from China that could be distinguished from other species in the genus based on aeciospore or urediniospore morphology and phylogenetic placement. The first species, P. jiangxiense, is characterized by a urediniospore surface structure with stout spines that are basally embedded in the wrinkled spore wall. The second species, P. leucoaecium, is characterized by an aeciospore surface structure with irregularly elongated verrucae. Taxonomic descriptions and illustrations are provided.
Keywords: 3 new taxa; Phylogeny; Pucciniales; Pucciniomycotina; Rosaceae; taxonomy.