Phylogenetic relationships and generic affinity of Uncinula septata inferred from nuclear rDNA sequences

Abstract

Based on 18S, 5.8S, and 28S rDNA sequences, the phylogenetic position of Uncinula septata within the Erysiphales has been inferred. Although appendages of the ascomata are uncinula like, i.e., unbranched with curved-coiled apices, U. septata is situated at the very base of the large Erysiphales cluster, far away from the “pseudoidium clade” (Erysiphe emend., including Microsphaera and Uncinula). Morphologically, U. septata differs from the species of Erysiphe sect. Uncinula (≡Uncinula) in having terminal, pluriseptate ascoma appendages, curved ascospores, and the absense of an anamorph. This species is a basal, tree-inhabiting powdery mildew with some additional ancestral characteristics, viz., uncinula-like appendages and 8-spored asci. The new genus Parauncinula with U. septata as the type species is proposed. Uncinula curvispora (≡U. septata var. curvispora) is tentatively maintained as a separate species, which is also assigned to Parauncinula.