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

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>Albi, Hydnum, Pallidi</i>, and <i>Rufescentes</i>; sections <i>Hydnum, Olympici, Magnorufescentes</i>, and <i>Rufescentes</i>; and subsections <i>Mulsicolores, Rufescentes</i>, and <i>Tenuiformia</i>.