Taxonomy and Phylogeny of Stipitate Stereoid Basidiomycetes from China

Stipitate stereoid fungi are saprotrophic basidiomycetes characterized by a leathery basidiome, a central-to-lateral stipe and infundibuliform pilei. Although numerous species of stipitate stereoid fungi have been recorded worldwide, understanding of their phylogenetic relationships remains extremely limited, and research on this group of fungi in China is insufficient. In this study, specimens of the three stipitate stereoid genera, namely Podoscypha s. l., Cymatoderma s. l. and Stereopsis s. l., from southern China were investigated. Phylogenetic analyses of the internal transcribed spacer (ITS) regions and the large subunit of the nuclear ribosomal RNA gene (LSU) using maximum likelihood (ML) and Bayesian inference (BI) methods revealed that all three genera are polyphyletic. Consequently, Podoscypha s. s. and Cymatoderma s. s. were delimited, and Cladoderris—previously synonymized with Cymatoderma—was resurrected. Cladoderris is characterized by an imbricate basidiome, tomentose pilei and basidiospores typically shorter than 4 μm in length. Three new species, Podoscypha casiae, Stereopsis buccinata and Cladoderris perennis, were described and illustrated. The morphological distinctions and affinities between the new species and closely related taxa were discussed, the thresholds for the intraspecific and interspecific demarcation within the three genera in this study were provided, and identification keys for the species of each genus were presented.