Morphological and phylogenetic analyses reveal Xenosporidesmiaceae fam. nov, with seven Xenosporidesmium species

This study introduces a new family, Xenosporidesmiaceae, and describes a novel genus, <i>Xenosporidesmium</i>, along with a new species, <i>Xenosporidesmium caohaiense</i>, based on morphological and phylogenetic analyses. Multi-locus phylogenetic reconstruction (LSU, SSU, ITS, and <i>rpb</i>2) revealed that the new family forms a distinct clade, diverging from Sporidesmiales and Distoseptisporales in Sordariomycetes, and supporting its taxonomic independence. The new species, <i>X. caohaiense</i>, is characterized by dark brown conidiophores and pale brown, distoseptate conidia with mucilaginous sheaths. Additionally, six previously described <i>Sporidesmium</i> species are reclassified into <i>Xenosporidesmium</i>. This study emphasizes the significance of molecular data in resolving taxonomic ambiguities among morphologically similar but phylogenetically divergent fungi, thereby contributing to the understanding of freshwater fungal diversity.