Morphology and multi-gene phylogeny reveal three new species of Clonostachys and two combinations of Sesquicillium (Bionectriaceae, Hypocreales) from Xizang, China

<i>Clonostachys</i> and <i>Sesquicillium</i> are genera in Bionectriaceae, and known in sexual perithecial ascomata and hyphomycetous asexual morphs. In their asexual morph, both genera share similar morphology in conidiophores and conidiogenous cell characteristics but differ in the development of conidiophores. The members of <i>Clonostachys</i> are distributed worldwide with the majority occurring in the tropics and the species are commonly reported as soil-borne fungi but also reported as endophytes, epiphytes, and saprotrophs. During a microfungi survey in Xizang, China, six collections of fresh and healthy <i>Ageratinaadenophora</i> and <i>Houttuyniacordata</i> leaves were obtained. The taxonomy of these collections was investigated through a combination of morphological analysis and multigene phylogenetic analysis using Maximum likelihood and Bayesian inference. The newly generated sequences were clustered within <i>Clonostachys</i> and <i>Sesquicillium</i>, showing hyphomycetes asexual morph. The results revealed three new <i>Clonostachys</i> species viz, <i>Clonostachyslinzhiensis</i>, <i>C.motuoensis</i>, and <i>C.yadongensis</i>. This research sheds light on the overlooked fungal diversity in Xizang, China, expanding the known fungal biodiversity in the region. Additionally, two new combinations, <i>Sesquicilliumaquaticum</i> and <i>S.shanghaiense</i> for <i>C.aquatica</i> and <i>C.shanghaiensis</i>, and one synonymy, <i>C.viticola</i> for <i>C.swietenia</i> are established, respectively.