Introducing Muciflexus inthanonensis gen. et sp. nov. and updates on Ochronectria (Hypocreales): New insights from leaf litter fungi in Doi Inthanon National Park, Northern Thailand

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