Identifying and naming the currently known diversity of the genus <i>Hydnum</i>, with an emphasis on European and North American taxa

<p>In this study, 49 species of <i>Hydnum</i> are recognized worldwide. Twenty-two of them are described here as new species. Epitypes are proposed for <i>H. repandum</i> and <i>H. rufescens</i>. The majority of the species are currently known only from a single continent. The barcodes produced in this study are deposited in the RefSeq database and used as a basis to name species hypotheses in UNITE. Eleven infrageneric clades recovered in a phylogenetic analysis are supported by morphological characteristics and formally recognized: subgenera <i>Alba, Hydnum, Pallida</i>, and <i>Rufescentia</i>; sections <i>Hydnum, Olympica, Magnorufescentia</i>, and <i>Rufescentia</i>; and subsections <i>Mulsicoloria, Rufescentia</i>, and <i>Tenuiformia</i>.</p>