The genus Brevicellicium encompasses wood-inhabiting corticioid fungi characterized by isodiametric subhymenial hyphae, short basidia, and smooth, often subangular spores with a distinct apiculus. Eight new LSU nrDNA sequences and 13 new ITS nrDNA of this genus, including the type species, were aligned with 47 and 42 accessions respectively of species of Trechisporales obtained from GenBank, and phylogenetic analyses were performed. The order Trechisporales was confirmed as a monophyletic group; the genera Porpomyces, Sistotremastrum, Subulicystidium and Trechispora form a highly supported clade where all Brevicellicium sequences are included. Our analyses also support that this genus belongs to Hydnodontaceae. A new species, Brevicellicium atlanticum from the Azores Archipelago, is described.
Keywords: Agaricomycetes; Basidiomycota; Corticioid fungi; ITS; LSU nrDNA; Phylogeny; Taxonomy.