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, <i>Diaporthethailandica</i> (Diaporthaceae) and <i>Occultithecachiangraiensis</i> (Xylariaceae), from woody litter materials. We also describe a new host record of <i>D.tulliensis</i> and a new geographical record for <i>D.melonis.</i> All collections were identified based on morphology and phylogenetic analyses of combined datasets. The morphologies of the taxa fit the generic concepts of <i>Diaporthe</i> and <i>Occultitheca</i>, respectively. <i>Diaporthethailandica</i> formed a sister clade with <i>D.raonikayaporum</i> but differs from <i>D.raonikayaporum</i> in the sizes of conidiomata, conidiogenous cells, and beta conidia. <i>Diaporthethailandica</i> also differs from <i>D.raonikayaporum</i> by the absence of gamma conidia. <i>Occultithecachiangraiensis</i> differs from the sister taxon <i>O.rosae</i> in having smaller ascomata and a thicker mucilaginous sheath. We also provide a synopsis of <i>Occultitheca</i> 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.