Morphological and Molecular Evidence Reveal Eight New Species of Gymnopus from Northeast China

Gymnopus is a widely distributed genus consisting of about 300 species thus far, including Gymnopus fusipes as a generic type. A total of nine species from China belong to the sect. Levipedes, including eight new species—Gymnopus longisterigmaticus, Gymnopus longus, Gymnopus macrosporus, Gymnopus striatus, Gymnopus changbaiensis, Gymnopus tomentosus, Gymnopus tiliicola, and Gymnopus globulosus—which were delimited and proposed based on morphological and molecular evidence; and one new record from Jilin Province, China—Gymnopus erythropus. Detailed descriptions and illustrations are presented, as well as comparisons to similar species. Overall, our results broaden the morphological characterization of the genus. The pileipellis of sect. Levipedes typically takes on the “Dryophila structure”, while, in our findings, pileipellis terminal hyphae inflated to spherical to prolate were observed, in addition to extremely long basidia sterigma. The phylogenies inferred from the ITS and nLSU dataset supported the Gymnopus, which was defined by Oliveira et al. as a monophyletic genus, and the novel species as separate lineages within. A key to all species described in this study is also provided.