Three new records of powdery mildews found in Mexico with one genus and one new species proposed

Cystotheca lanestris on the new host Quercus canbyi, Microidium bauhiniicola on the new host Bauhinia macranthera and an undescribed species of Phyllactinia on Mimosa aculeaticarpa have recently been collected in Mexico. Analyses of morphological traits and molecular sequence data led to identifications of the causal agents of the powdery mildew diseases involved. Microidium bauhiniicola, hitherto only known from Argentina and Brazil, is new to Mexico. The phylogenetic analysis revealed an isolated position distant from Microidium indicating an undescribed genus, which is introduced as Bulbomicroidium gen. nov. Sequences derived from a Mexican specimen of C. lanestris on Quercus canbyi agree completely with other North American sequences, but differ from sequences retrieved from Asian collections, suggesting that C. lanestris in Asia is not conspecific with C. lanestris s. str. in North America. A new species of Phyllactinia on Mimosa malacophylla is morphologically similar to P. dalbergiae but readily distinguishable by differences in the asexual morph. Based on morphological peculiarities and results of molecular sequence analyses, this species is described as Phyllactinia mimosae sp. nov.