Contributions to the knowledge of the phylogeny and taxonomy of the Erysiphaceae (powdery mildews) – Part 1

Abstract

The phylogeny and taxonomy of several powdery mildews (Erysiphaceae) have been examined. Sequences of the rDNA ITS region retrieved from several collections of Erysiphe spp. belonging to the E. aquilegiae complex (cluster) and collected on new hosts are listed and discussed, including a critical assessment of the phylogenetic-taxonomic interpretation of this complex. Based on results of sequence analyses, E. tortilis proved to pertain to this complex as well. This species is epitypified, which is supplemented with an ex-epitype reference sequence. The phylogeny and taxonomy of the powdery mildew on Manihot esculenta (cassava, manioc), which is widespread and common wherever this tuber crop is cultivated, has been examined. Morphological re-examinations and phylogenetic analyses of collections from Argentina and Brazil revealed that this powdery mildew belongs to the genus Erysiphe, phylogenetically included in the E. trifoliorum complex. The new combination Erysiphe manihoticola is introduced for this powdery mildew. Based on the re-examination of type material, it has become clear that the name Oidium manihotis, which was used in the past for this powdery mildew, is not conspecific with E. manihoticola and most likely not congeneric with Erysiphe. On the basis of sequences retrieved from type material of Erysiphe baptisiae and a North American collection on Baptisia, we reveal that E. baptisiae has to be reduced to synonymy with E. guarinonii. Erysiphe euonymicola on Euonymus fortunei is recorded from North America for the first time. The identity of Golovinomyces on Cynara and Echinops in North America is discussed. Type material of Golovinomyces echinopis has been sequenced, and G. montagnei is epitypified with a collection from Germany, which is supplemented by ex-epitype sequence data. Based on morphological analyses and a comparison of sequence data with ex-holotype sequences, North American powdery mildew collections on Echinops could be confirmed to belong to G. echinopis. However, a North American powdery mildew collection on Cynara cardunculus turned out to be close to G. depressus and not, as expected, to G. montagnei. Golovinomyces verbenae, described from North America, is epitypified with ex-epitype sequence data, and G. glandulariae, recently described from Australia, is reduced to synonymy with G. verbenae. The phylogenetic positions of Podosphaera physocarpi and P. spiraeae-douglasii have been revealed on the basis of collections from North America and Germany (the first record for Germany and the second for Europe of P. physocarpi), including the first descriptions, pictures and illustrations of the asexual morphs for both of these species. Furthermore, Podosphaera prunicola is epitypified.