Abstract
Phylogenetic and morphological analyses have been conducted on powdery mildew specimens on different Berberis and Mahonia spp. from Asia, Europe and North America. The present study showed that collections of Erysiphe berberidis exhibit a high degree of morphological plasticity of the sexual morph, in contrast to their morphologically, rather uniform, asexual morph. In phylogenetic tree, all sequences cluster in a large strongly supported clade, without any indication and support for further differentiation into cryptic species. There are three morphological types within E. berberidis s. lat. that contain consistent differences. Until future multi-locus analyses will be available, we prefer to treat these 'morphological types' as varieties. These include Erysiphe berberidis var. berberidis, E. berberidis var. asiatica, and E. berberidis var. dimorpha comb. nov. (≡ Microsphaera berberidis var. dimorpha, M. berberidicola, and M. multappendicis). To fix the application of species name E. berberidis, an appropriate epitype was designated, with an ITS sequences.