The application of the name Xylaria hypoxylon, based on Clavaria hypoxylon of Linnaeus*

Although Xylaria hypoxylon is one of the most familiar fungi of temperate regions, the basionym of the name, Clavaria hypoxylon of Linnaeus, has remained untypified. Here we assess the original five elements included in the 1753 protologue; no candidate specimen was located but two illustrations Linnaeus cited were considered, one a mixture of species and the other fanciful. As the name is sanctioned, following clarifications in the Melbourne Code, elements cited by Fries when the name was sanctioned in 1823 are also candidates for lectotypification. In addition to various illustrations, Fries cites two exsiccatae, and one from his own Scleromycetes Suecicae distributed in 1821 is designated as lectotype for Linnaeus' name here. In view of the complexity of the group as revealed by molecular systematic work, and the poor state of the Fries material, we also designate a sequenced epitype from Sweden. We stress the importance of examining fungi in the complex in the sexual state, as those that are asexual can be difficult to identify conclusively. Figures of the original protologues and the most pertinent illustrations and specimens are provided, along with a detailed description and illustrations based on recent collections.