A new species of Stamnaria is described based on morphology and molecular data from a collection made in West Siberia. Stamnaria yugrana is differentiated by lanceolate, strongly protruding paraphyses and comparatively narrow, fusoid-clavate ascospores. The apothecia are urn-shaped due to a prominent and even collar as in S. persoonii. The species grows on fallen side branches of Equisetum sylvaticum, a rarely recorded host for Stamnaria. The authors formally describe the new species and provide colour illustrations. In addition, the literature is reviewed on previously described species of Stamnaria. Phylogenetic reconstruction of the Stamnaria lineage, based on the ITS ribosomal DNA, strongly supports the three currently recognised species: S. americana, S. persoonii and S. yugrana.
Keywords: Ascomycota; Equisetum; ITS rDNA; Stamnaria; ecology; taxonomy.