<i>Crassisporium</i> and <i>Romagnesiella</i>: two new genera of dark-spored Agaricales

A systematic study of a rare and enigmatic European species, <i>Galerina clavus</i> Romagn., is presented. Phylogenetic analyses show it to be most closely related to <i>Pachylepyrium carbonicola</i> (A.H. Sm.) Singer and <i>P. funariophilum</i> (M.M. Moser) Singer (Strophariaceae). Investigation of additional species of <i>Pachylepyrium</i> suggests this genus is polyphyletic as the type species, <i>P. fulvidula</i> (Singer) Singer, is nested in the Tubariaceae Vizzini based on multigene phylogenetic analyses. <i>Pachylepyrium nubicola</i> Singer is allied with <i>Pholiota</i> (Fr.) P. Kumm. based on high ITS similarity, and <i>P. carbonicola</i> and <i>P. funariophilum</i>, together with <i>G. clavus</i>, form a clade among a consortium of Strophariaceae Singer &amp; A.H. Sm. and Hymenogastraceae Vittad. As a result, we propose <i>Romagnesiella</i> gen. nov. to accommodate <i>G. clavus</i>, for which a taxonomic description is given and lectotype and epitype are designated. The genus <i>Crassisporium</i> gen. nov. is proposed to encompass <i>Pachylepyrium funariophilum</i> (of which <i>P. carbonicola</i> is considered a younger taxonomic synonym), <i>P. chilense</i> M.M. Moser, and <i>P. squarrulosum</i> Singer. <i>Crassisporium</i> is distinguished from <i>Romagnesiella</i> by its thick-walled basidiospores and occurrence in burnt habitats. The identities of the morphologically similar <i>Tubaria umbonata</i> S. Lundell, <i>T. embolus</i> (Fr.) Sacc. and <i>T. minima</i> J.E. Lange are also discussed.