Crassisporium and Romagnesiella: two new genera of dark-spored Agaricales

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