Taxonomic insights and preliminary enzyme assays of Rhytidhysteron species (Hysteriales, Hysteriaceae) from litter layer in the Yuan Jiang savanna, China.

Six terrestrial hysteriaceous fungi were collected from litter in dry-hot valleys, China, all exhibiting the typical morphological characteristics of the genus Rhytidhysteron. Detailed morphological examimation combined with RAxML phylogenetic analysis of combined LSU, SSU, ITS, and tef-1α loci revealed that the specimens represent one new species Rhytidhysteron savanniense sp. nov. and two new geographical records R. hongheense and R. tectonae. Comprehensive descriptions, illustrations, and a phylogenetic tree are provided to clarify the taxonomic placement of these taxa. As a preliminary observation, lignocellulose-related enzymes screening was conducted to explore potential ecological roles of Rhytidhysteron. The results indicated variation in cellulase production capacity among species, with Rhytidhysteron savanniense exhibiting the highest cellulase activity under laboratory conditions. These findings highlight the taxonomic diversity of Rhytidhysteron in dry-hot valley ecosystems and suggest possible functional capapcites that warrant further ecological investigation.