Morphology and Phylogeny of Pestalotiopsis (Sporocadaceae, Amphisphaeriales) from Fagaceae Leaves in China.

Fagaceae is a family of flowering plants widely distributed in the Northern Hemisphere, including deciduous and evergreen trees and shrubs. Species of Pestalotiopsis are well-known agents of leaf spot diseases, but targeted sampling on Fagaceae is still missing. To determine the diversity of Pestalotiopsis species associated with Fagaceae leaf spot in China, investigations were conducted in the main areas of Fagaceae distribution from 2016 to 2021. Diseased leaf tissues were collected, and fungal isolates were obtained from leaf spots. In the present study, 43 isolates of Pestalotiopsis were studied based on combined morphology and phylogeny. As a result, 10 new species were identified, viz., Pestalotiopsis anhuiensis, P. castanopsidis, P. changjiangensis, P. cyclobalanopsidis, P. foliicola, P. guangxiensis, P. guizhouensis, P. lithocarpi, P. shaanxiensis, and P. silvicola, and six new host records were recognized. IMPORTANCE Pestalotiopsis is a common fungal genus inhabiting plant tissues as endophytes, pathogens, and saprophytes. Fagaceae is a plant family including many important tree species, such as Castanea mollissima and Quercus spp. In this study, diseased leaves of Fagaceae in China were investigated, and 16 Pestalotiopsis species were identified based on morphology and phylogeny of combined loci of internal transcribed spacers (ITS), the translation elongation factor 1-α (tef1), and the beta-tubulin (tub2) genes. Among these, 10 new species were found, and six new host records were revealed. Our study significantly updates the taxonomy of Pestalotiopsis and enhances our understanding of leaf diseases of Fagaceae hosts.