Molecular phylogeny and taxonomy of Parauncinula (Erysiphales) and two new species P. polyspora and P. uncinata

Parauncinula, a genus belonging to the Erysiphaceae (powdery mildew family), consisted of only two species, P. curvispora and P. septata, which are distributed only in China and Japan (endemic to East Asia). This genus split from other powdery mildew genera at an early stage of evolution, and thus has been considered as one of the most ancestral genera in the Erysiphales. Phylogenetic analyses using rDNA internal transcribed spacer (ITS) region and 28S rRNA gene sequences indicated that one of the species, P. septata, is divided into three distinct genotypes. The ITS sequence similarities between the three genotypes were 96% or less, suggesting species level differences among the genotypes. Combined with detailed morphological observations, P. septata s. lat. is divided into three species, viz. P. septata s. str., P. polyspora, and P. uncinata. These species are clearly defined by morphological characteristics such as the number of ascospores per ascus and morphology of appendages, as well as DNA sequences. A key to the species of Parauncinula is also presented.