Xenosporidesmiaceae L. L. Liu & Z. Y. Liu 2025, fam. nov.

Xenosporidesmiaceae L. L. Liu & Z. Y. Liu fam. nov. Etymology. Referring to the name of the type genus. Description. Colonies on nature substrate effuse, hairy, scattered or in small groups. Conidiophores macronematous, mononematous, solitary, cylindrical, straight or slightly flexuous, dark brown, septate. Conidiogenous cells holoblastic, monoblastic, integrated, terminal, cylindrical, smooth, pale to dark brown. Conidia acrogenous, solitary, obclavate, pale brown to olivaceous, paler at the apex, tapering gradually towards the apex, smooth, straight or curved, distoseptate, with a mucilaginous sheath or apical appendage. Type genus. Xenosporidesmium L. L. Liu & Z. Y. Liu, gen. nov. Notes. The new family Xenosporidesmiaceae is established to accommodate a distinct lineage comprising six Sporidesmium species and one new species described herein. This lineage forms a highly supported clade (ML / BS = 100 %, BYPP = 1) in the multi-gene phylogeny (LSU, SSU, ITS, and rpb 2), diverging from both Sporidesmiales and Distoseptisporales. All members share pale brown, sheathed or appendaged conidia and are exclusively associated with freshwater habitats (Hyde et al. 2016; Liu et al. 2019; Wang et al. 2024). The family is proposed to resolve the phylogenetic placement of these morphologically similar yet evolutionarily distinct taxa, and its establishment aims to avoid taxonomic confusion with the currently recognized Sporidesmium sensu stricto.