Taxonomy and phylogeny of Stereaceae (Russulales, Basidiomycota): two new genera, nine new species and twenty new combinations.

An in-depth study of the taxonomy and phylogeny of the Stereaceae was conducted. Specimens collected from East Asia were studied by using morphological and molecular systematic methods. The phylogenetic analyses were based on a concatenated ITS1-5.8S-ITS2 (ITS) and the D1-D2 domains of nuc 28S rDNA (LSU) sequence data of Stereaceae by using the maximum parsimony, maximum likelihood and Bayesian inference methods. Fourteen lineages including two new genera, Confertotrama and Gelatinostereum, are recognized in the phylogenetic tree. Confertotrama, typified by Merulius rugulosus, is segregated from Gloeocystidiellum s. lat. Gelatinostereum is sister to Stereum in the tree but differs in having gelatinous basidiomes and lacking thick-walled pseudocystidia. Conferticium is shown to be restricted to include species with smooth basidiospores, while species with ornamented basidiospores are nested within the Gloeocystidiopsis lineage. The delimitation of Megalocystidium is expanded based on the phylogenetic analyses. It includes species with or without clamp connections and acanthohyphidia and with a large variety of basidium size. Neoaleurodiscus is treated as a later synonym of Aleurodiscus sensu stricto, since their type species N. fujii and A. amorphus were nested within the same lineage. With this disposal, Aleurodiscus s. str. now includes species with smooth or ornamented basidiospores. The generic name, Gloeomyces is applied for the lineage of species of Aleurodiscus s. lat. with resupinate basidiomes, well-developed acanthohyphidia and smooth basidiospores, while Acanthophysellum is regarded as a synonym of Xylobolus. Nine new species, Aleurodiscus globisporus, Conferticium subtropicum, Gelatinostereum phlebioides, Gloeocystidiopsis shenghuae, Gloeomyces subcerussatus, Megalocystidium brunneum, M. effusum, Stereum rhododendri and S. tropicum are described and illustrated from China. Twenty new combinations, Aleurodiscus fujii, Confertotrama aspella, Ca. macrospora, Ca. rugulosa, Ca. rajchenbergii, Gloeocystidiopsis ravum, Gs. tenuissimus, Gloeomyces bambusinus, G. bicornis, G. cerussatus, G. dextrinoideocerussatus, G. dextrinoideophyses, G. formosanus, G. parvisporus, G. persicus, G. thailandicus, G. thoenii, G. tropicus, Megalocystidium chinense and Xylobolus lividocoeruleus are proposed. Aleurodiscus isabellinus is treated as a synonym of Gloeomyces graminicola. Morphological differences between closely related genera are discussed, and an identification key to all 14 genera of Stereaceae is presented. Citation: Xu YL, Cao YF, Liu SL, Nakasone KK, He SH (2025). Taxonomy and phylogeny of Stereaceae (Russulales, Basidiomycota): two new genera, nine new species and twenty new combinations. Persoonia 54: 119-145. doi: 10.3114/persoonia.2025.54.04.