Morphology and phylogeny of two new species within Cordycipitaceae (Hypocreales) from China

<i>Simplicillium</i> and <i>Leptobacillium</i>, sister genera in the family Cordycipitaceae, exhibit a broad range of hosts or substrates. The identification of two novel species, from <i>Simplicillium</i> and <i>Leptobacillium</i>, was achieved by analysing morphological characteristics and phylogenetic data obtained from six molecular markers (ITS, nrSSU, nrLSU, <i>tef-1α</i>, <i>rpb1</i> and <i>rpb2</i>). The two recently documented species are <i>S.puwenense</i> and <i>L.longiphialidum</i>. Morphologically, <i>S.puwenense</i> possessed slender solitary rod-shaped or columnar phialides with elliptical oval or cylindrical conidia forming small spherical heads at the apex of phialides. On the other hand, <i>L.longiphialidum</i> had solitary columnar phialides with elliptic or subspherical apical conidia while other conidia were narrow columnar or fusiform in shape. Phylogenetic analysis revealed that <i>S.puwenense</i> formed an independent branch as a sister species to <i>S.formicae</i>, whereas <i>L.longiphialidum</i> clustered with <i>L.marksiae</i> exhibiting stable topological structure. The Bayesian inference posterior probability and the maximum likelihood bootstrap-ratio provided robust statistical evidence, indicating the presence of two novel species within the genera of <i>Simplicillium</i> and <i>Leptobacillium</i>. The present study contributes to the discovery of species diversity in <i>Simplicillium</i> and <i>Leptobacillium</i>, while also providing a taxonomic foundation for their rational development and sustainable utilisation.