Phylogenetic evidence reveal a close relationship between Amphichorda and Ovicillium in Bionectriaceae (Hypocreales)

Animal excrement serves as the primary substrate for <i>Amphichorda</i>, which is found in a wide range of habitats. Based on evolutionary relationships, the genus is currently classified within the Bionectriaceae. However, the phylogenetic position of <i>Amphichorda</i> and its associated taxa remains unresolved due to limited sampling in previous studies. Here, we discovered and identified five <i>Amphichorda</i> species, significantly advancing our understanding of this genus. Using six genomic loci (ITS, nrSSU, nrLSU, <i>tef1α</i>, <i>rpb1</i>, and <i>rpb2</i>) to expand taxonomic sampling, we reconstructed a phylogenetic framework for the Bionectriaceae, with a focus on <i>Amphichorda</i> and related taxa. Phylogenetic analyses revealed a close genetic connection between <i>Amphichorda</i> and related genera, yet they formed distinct clades within the Bionectriaceae and were clearly differentiated. The extensive sampling demonstrated stable phylogenetic relationships among <i>Amphichorda</i>, <i>Hapsidospora</i>, <i>Ovicillium</i>, <i>Proxiovicillium</i>, and <i>Bulbithecium</i>. Furthermore, we described two new species, <i>A.guizhouensis</i> <b>sp. nov.</b> and <i>O.pseudoattenuatum</i> <b>sp. nov.</b>, supported by DNA data and morphological characteristics. A comprehensive comparison of morphological traits across all members of <i>Amphichorda</i> and <i>Ovicillium</i> was conducted. This study clarifies taxonomic boundaries and evolutionary relationships within the two genera and contributes to the overall understanding of the biodiversity and systematics of the Bionectriaceae.