Four new species of <i>Agaricus</i> subgenus <i>Spissicaules</i> from China

Agaricus subgenus Spissicaules is widely distributed in the world. In this study, 114 specimens were included multigene phylogenetic analyses that allowed a better circumscription of four sections A. subg. Spissicaules. Three new species from China, brunneovariabilis, beijingensis, and planiceps, are described placed different sections. The invalidly catenariocystidiosus validated here as an additional species. Comparisons between sequences three closely related thiersii, parasubrutilescens, linzhiensis support distinction these despite paraphyly linzhiensis, which results its high intraspecific variability with numerous heteromorphisms.