Unveiling Sordariomycetes taxa associated with woody litter in Northern Thailand.

Sordariomycetes species are abundant in woody litter samples. In this study, we introduce two novel species, Diaporthethailandica (Diaporthaceae) and Occultithecachiangraiensis (Xylariaceae), from woody litter materials. We also describe a new host record of D.tulliensis and a new geographical record for D.melonis. All collections were identified based on morphology and phylogenetic analyses of combined datasets. The morphologies of the taxa fit the generic concepts of Diaporthe and Occultitheca, respectively. Diaporthethailandica formed a sister clade with D.raonikayaporum but differs from D.raonikayaporum in the sizes of conidiomata, conidiogenous cells, and beta conidia. Diaporthethailandica also differs from D.raonikayaporum by the absence of gamma conidia. Occultithecachiangraiensis differs from the sister taxon O.rosae in having smaller ascomata and a thicker mucilaginous sheath. We also provide a synopsis of Occultitheca species with details on their morphology, host, and country. These findings provide valuable insights into the diversity and ecological roles of Sordariomycetes, emphasising the need for continued exploration of fungal biodiversity in various environments.