DNA barcoding and scanning electron microscopy reveals Erysiphe ahmadii sp. nov. and a new record Erysiphe populicola (Erysiphaceae, Helotiales) on salicaceous hosts from Pakistan

A new species of powdery mildew fungus Erysiphe ahmadii and a new record, Erysiphe populicola, on Salicaceae are described from Pakistan. In addition to light microscopy, scanning electron microscopy is also done to clearly demonstrate the surface characters of chasmothecia. E. ahmadii sp. nov. is characterized by large conidia ((-26)29-35(-37) - (-16)17-21(-23) mu m), long chasmothecial appendages (198-286 mu m) and small conidiophores. The novelty is confirmed by analyzing the genetic variation of internal transcribed spacer region (ITS1-5.8S-ITS2) of the ribosomal DNA gene, a universal fungal marker. E. populicola is characterized for the first time using molecular phylogenetic markers. Detailed descriptions along with scanning electron microscopy (SEM) photographs are provided in this paper.