Erysiphe wadae: a new species of Erysiphe sect. Uncinula on Japanese beech

Abstract

A new species of Erysiphe sect. Uncinula is described and illustrated from Japan. Erysiphe wadae sp. nov., found on Japanese beech (Fagus crenata, Fagaceae), is characterized by having two types of appendages, i.e., a long (true) appendage arising from the equatorial zone of the ascomata, and a short appendage arising from the upper part of the ascomata. This characteristic is shared by E. simulans, E. australiana, E. flexuosa, E. liquidambaris, E. prunastri, and E. togashiana. Erysiphe wadae differs from the latter five species in its brown-colored appendage. Erysiphe simulans is most similar to E. wadae, but differs in its loosely uncinate appendage and smaller number of ascospores. Identity of the nucleotide sequences of the rDNA ITS region is 92.3% between the two species. The significance of the two types of appendage in taxonomy and phylogeny of powdery mildews is discussed based on molecular phylogenetic analysis.