Three lignicolous freshwater fungi of Neohelicomyces (Tubeufiales, Tubeufiaceae) from Guizhou Province, China

Lignicolous freshwater fungi are key decomposers in freshwater ecosystems, playing crucial roles in nutrient cycling and energy flow. During investigations into microfungi in freshwater habitats in Guizhou Province, China, six specimens of Neohelicomyces were collected from submerged decaying wood. Detailed morphological examinations, together with multi-gene phylogenetic analyses based on LSU, ITS, rpb 2 and LSU 1-α sequence data, were conducted to clarify their taxonomic placements. Phylogenetic results revealed that these collections represent two novel species, N. brevis and N. wujiangensis , and one known species, N. astrictus , which is reported here as a new habitat record from a freshwater habitat. The two new species can be distinguished from their closest relatives by differences in conidiophore morphology, conidial size and septation, and colony characteristics, and are well supported as independent lineages in the phylogenetic analyses. This study expands the species diversity of Neohelicomyces and highlights freshwater ecosystems in southwestern China as important reservoirs of helicosporous hyphomycetes diversity.