Systematic study of Panaeolus (Agaricales, Galeropsidaceae) sensu lato and psilocybin-producing traits of species from China

<i>Panaeolus</i> sensu lato is a group of hallucinogenic mushrooms commonly found on dung, in pasture areas, grasslands, and forests. Previous studies indicated that the <i>Panaeolus</i> s.l. clade (panaeo-clade) could be ranked as a family (<i>Galeropsidaceae</i>), pending further evidence. In this study, based on phylogenomic, multigene phylogenetic, molecular clock, and morphological analyses, the panaeo-clade is demonstrated to be a distinct family, separate from <i>Bolbitiaceae</i>. The taxonomic system of <i>Galeropsidaceae</i> is revised. The genera accepted in <i>Galeropsidaceae</i> are <i>Panaeolus</i> and <i>Staktophyllus</i>, whereas <i>Crucispora</i> and <i>Panaeolopsis</i> are synonymized under <i>Panaeolus</i>. Three subgenera are accepted in <i>Panaeolus</i>: subg. Bresadolomyces, subg. Panaeolina, and subg. Panaeolus. Subgenus Bresadolomyces is roughly equivalent to the traditional circumscription of subg. Copelandia but is extended to include species formerly placed in <i>Crucispora</i>. Subgenus Panaeolina comprises most species from China and Anellaria-like species. Subgenus Panaeolus mainly comprises the <i>P. papilionaceus</i> species complex and a western Asian clade represented by <i>P. punjabensis</i>. In this study, one new subgenus and eight new species are proposed. Species from China are documented with descriptions, photographs, and illustrations. Additionally, the psilocybin-producing traits of 14 species were tested using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Two species are confirmed to possess psilocybin-producing traits, namely the known species <i>P. cinctulus</i> and the new species <i>P. subfoenisecii</i> proposed in this study. The evolution of the coprophilous lifestyle and psilocybin-producing traits in <i>Panaeolus</i> is also discussed based on phylogenetic relationships and divergence times.