Lagarobasidium cymosum is a rare corticioid species with characteristic morphology different from other Lagarobasidium species. We used nuc 5.8S rDNA, nuc 28S rDNA, and mt 12S rDNA loci to infer the phylogenetic position of L. cymosum. Our analyses suggest that it belongs to Xylodon but is not closely related to any of the other taxa referred to Lagarobasidium. Molecular and morphological information shows that the traditional concept of L. cymosum covers at least three species: Xylodon acuminatus from the Neotropics, X. cymosus from North America, and X. subtilissimus distributed in both Europe and North America. Lagarobasidium calongei is transferred to Xylodon, and DNA barcodes for Lyomyces incrustatus and Xylodon hjortstamii are published for the first time.
Keywords: 4 new taxa; Hymenochaetales; Lyomyces; Peniophora cymosa; Xylodon; phylogeny.