The Combination of Morphological and Phylogenetic Evidence Reveals Four New Gymnopus Species and New Distribution.

The genus Gymnopus plays a significant role in ecological systems, with certain species holding potential as food or medicinal resources. However, the species diversity of Gymnopus in China remains unclear. In recent years, more than one thousand Gymnopus specimens have been collected across China. Thus, through the integration of ecological evidence, detailed morphological studies, and phylogenetic analysis using a multiloci dataset of ITS + nLSU + tef1-ɑ, four new species-Gymnopus longistipes, Gymnopus striatipileatus, Gymnopus viridiscus, and Gymnopus spadiceus-have been differentiated from known species. Gymnopus similis has been newly documented from Jiangxi Province, China. Detailed descriptions and vivid illustrations have been provided based on the newly collected specimens, along with comparisons to closely related species. Additionally, a key to the reported species of Gymnopus s.l. from East China has been included.