Abstract
While exploring the leaf litter fungal diversity in Doi Inthanon National Park, Northern Thailand, we discovered a previously unknown lineage within Niessliaceae. Muciflexusinthanonensis gen. et sp. nov. is therefore introduced to accommodate this new lineage. The link between the sexual and asexual morphs of Ochronectriathailandica is also established, while the generic description of Ochronectria is updated. A polyphasic approach was employed, consisting of multi-locus phylogenetic analysis using ITS, LSU, rpb2, and tef1-α along with the morphological evidence to support the findings. Muciflexusinthanonensis resembles the spore morphology of Phialoseptomonium even though they are phylogenetically distant. Muciflexusinthanonensis forms a sister clade with Trichonectriasetadpressa, characterised by a long branch, but differs in asexual morphology, possessing clusters of simple or branched conidiophores compared to the sporodochia-like structure of T.setadpressa. The discovery of the asexual morph of Ochronectriathailandica from a terrestrial habitat confirms the versatile nature of the fungus, which inhabits both aquatic and terrestrial environments. Here we establish the link between the sexual and asexual morphs of Ochronectria by revealing the holomorphic nature of O.thailandica. This study highlights the diversity of leaf litter fungi and the potential of discovering novel fungal species in northern Thailand.