Morpho-phylogenetic analyses reveal Dentisympodium fusiforme gen. et sp. nov. in Pleurotheciaceae (Pleurotheciales, Savoryellomycetidae) from China

Pleurotheciaceae is a diverse family of hyphomycetous fungi within Pleurotheciales (Savoryellomycetidae), comprising numerous saprobic species that contribute to the decomposition of organic matter in freshwater ecosystems. Although the family has undergone considerable taxonomic expansion in recent years, its diversity remains insufficiently documented, particularly in freshwater habitats, where novel lineages continue to be discovered. During investigations of freshwater fungi associated with submerged decaying wood in Guizhou Province, China, fungal specimens were collected and examined using morphological observations and multigene phylogenetic analyses. Phylogenetic relationships were inferred from a concatenated dataset comprising the ITS, LSU, SSU, and rpb 2 loci, and morphological characteristics were compared with those of related genera within Pleurotheciaceae. The results revealed a distinct lineage within Pleurotheciaceae, for which the new genus Dentisympodium is introduced to accommodate the new species D. fusiforme . Phylogenetic analyses placed Dentisympodium within Pleurotheciaceae with strong statistical support. The genus is currently known only from its asexual morph and is characterized by macronematous, mononematous, erect, unbranched, subcylindrical, flexuous, hyaline conidiophores; holoblastic, polyblastic, integrated, terminal, sympodial, irregularly subcylindrical conidiogenous cells bearing denticles; and solitary, acropleurogenous, predominantly 3-septate, cylindrical, fusiform to obclavate, hyaline conidia. Morphological comparisons demonstrated that Dentisympodium is readily distinguishable from other genera of Pleurotheciaceae, particularly by its pseudodactylaria-like conidia and unique conidiogenous apparatus. The introduction of Dentisympodium expands the morphological and phylogenetic diversity currently recognized within Pleurotheciaceae and highlights the importance of continued exploration of freshwater fungi for uncovering previously unknown fungal taxa and refining the taxonomy of the family.