Taxonomic revision of species of and on , including two new species from China.

and are the only species of genus that parasitize plants belonging to genus (Rosaceae). Systematic revision of the genus 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 and belong to a group of species that also occur on . Morphological and molecular phylogenetic analyses revealed that these species were transferred to and renamed as and . Two new species were also discovered on from China that could be distinguished from other species in the genus based on aeciospore or urediniospore morphology and phylogenetic placement. The first species, , is characterized by a urediniospore surface structure with stout spines that are basally embedded in the wrinkled spore wall. The second species, , is characterized by an aeciospore surface structure with irregularly elongated verrucae. Taxonomic descriptions and illustrations are provided.