Biogeography and species diversity of freshwater <i>Savoryellomycetidae</i> ( <i>Sordariomycetes</i> ) fungi

The subclass Savoryellomycetidae (Sordariomycetes, Ascomycota) primarily consists of fungal saprobes on decayed wood from freshwater habitats. They are widely distributed worldwide with a higher diversity in Asia. This study comprehensively examines freshwater Savoryellomycetidae species in China, focusing on their diversity, taxonomy, phylogeny, and biogeography. A comprehensive multigene phylogenetic analysis of Savoryellomycetidae was performed to provide better taxonomic insights and classification of known species, resulting in the identification of 38 species, with detailed sample collection sites also provided. Among these, ten new species and three new combinations are introduced. Nine species are newly recorded in China. Both sexual and asexual morphs of Ascolacicola aquatica and Phaeoisaria filiformis are described. Additionally, some taxonomic uncertainties within existing classifications have been resolved through phylogenetic analyses and morphological characteristics. Furthermore, by integrating our data with previous studies, a biogeographic analysis of Savoryellomycetidae is conducted. This not only accurately depicts the number of species in this subclass but also reveals the global distribution of freshwater Savoryellomycetidae species. This study contributes valuable insights into the species diversity of Savoryellomycetidae fungi in freshwater habitats and offers a clearer understanding of the systematic relationships among taxa in this subclass.