Phylogeny and Taxonomic Revision of Pseudodiploospora (Hypocreales, Pseudodiploosporeaceae) Associated with White Mold Disease of Cultivated Morels in China

White mold disease (WMD) is one of the most destructive diseases affecting cultivated morels ( Morchella spp.) in China, yet the taxonomy and diversity of its associated pathogens remain poorly resolved. During targeted surveys of WMD from major morel-growing regions in 2023–2024, we obtained 518 isolates belonging to the genus Pseudodiploospora. Although these isolates had historically been treated as a single species, P. longispora, marked morphological variation and preliminary phylogenetic signals indicated the presence of a species complex. To reassess species boundaries, we employed multilocus phylogenetic analyses integrated with coalescent-based species delimitation and detailed morphological examination. Five distinct species were resolved, comprising P. longispora and four novel taxa: P. aequatospora , P. crassispora , P. curvispora , and P. tenuispora . Our results also support a taxonomic revision of Pseudodiploospora , refining generic limits and improving nomenclatural stability. This study provides the first comprehensive assessment of species diversity within Pseudodiploospora associated with WMD and establishes a robust taxonomic framework for future ecological and pathogenicity research.