Abstract: The fungal order Diaporthales constitutes a large and ecologically diverse group of microfungi, best known for their profound impact on woody plants as devastating phytopathogens and ubiquitous saprobes. Driven by accelerated species discovery, the classification of this order has become increasingly complex. Here, we present a comprehensively updated molecular phylogeny of Diaporthales, utilizing a concatenated dataset of ITS, LSU, rpb2, and tef1 sequences. By integrating recently published taxa with novel collections associated with woody plant diseases across China, we rigorously test and substantially refine the diaporthalean phylogenetic framework. To resolve deep-node polyphyly, Dwiroopaceae, Erythrogloeaceae, Foliocryphiaceae, Mastigosporellaceae, Harknessiaceae, Schizoparmaceae, and Ternstroemiomycetaceae are synonymized under Cryphonectriaceae, while Neomelanconiellaceae and Sinodisculaceae are reduced to synonymy under Melanconiellaceae. We introduce a novel family, Neophaeoappendicosporaceae, along with six new genera: Allomelanconiella, Clavatosporomyces, Ellipsospora, Lagenospora, Melanconiellopsis, and Paramelanconiella. Additionally, three novel species and seven new combinations are proposed. By rendering all currently accepted families strictly monophyletic, this study delivers a highly stable and predictive taxonomic backbone for Diaporthales. Ultimately, this framework will serve as a critical foundation for accurate global phytosanitary diagnostics, facilitate the discovery of cryptic pathogenic lineages, and promote future research on evolutionary ecology of plant-microbe interactions.

Key words: Ascomycota, Diaporthales, molecular phylogeny, novel taxa, taxonomic revision