Five new Cortinarius species, C. neobalaustinus, C. pseudocamphoratus, C. subnymphatus, C. wuliangshanensis and C. yanjiensis spp. nov., are proposed based on a combination of morphological and molecular evidence. Cortinarius neobalaustinus is characterized by a very weakly hygrophanous and yellowish-brown to brown pileus and small and weakly verrucose basidiospores. Cortinarius pseudocamphoratus can be characterized by a viscid pileus, a strongly unpleasant smell, amygdaloid to somewhat ellipsoid basidiospores and lageniform to subfusiform cheilocystidia. Cortinarius subnymphatus is identified by a strongly hygrophanous pileus that is reddish-brown with a black-brown umbo, a yellowish universal veil and ellipsoid to subamygdaloid basidiospores. Cortinarius wuliangshanensis is characterized by a moderately to strongly hygrophanous, translucently striated and yellowish to reddish-brown pileus and rather weakly and moderately verrucose basidiospores. Cortinarius yanjiensis is distinguished by a weakly to moderately hygrophanous and yellowish to brown pileus and moderately to rather strongly verrucose basidiospores. The phylogenetic analyses were performed with maximum likelihood and Bayesian inference methods based on the data set of nuc rDNA ITS1-5.8S-ITS2 (ITS), D1–D2 domains of nuc 28S rDNA (28S) and RNA polymerase II second largest subunit (rpb2), and the results show that C. neobalaustinus, C. wulianghsanensis and C. yanjiensis cluster in sect. Illumini, C. pseudocamporatus belongs to sect. Camphorati and C. subnymphatus belongs to sect. Laeti. In addition, a study of basidiospores under field emission scanning electron microscopy (FESEM) was conducted. An identification key for the five new species and related species from China is also provided.

Nine collections of gymnopoid fungi were studied based on morpho-molecular characteristics. The macromorphology was made according to the photograph of fresh basidiomata and field notes, while the micromorphology was examined via an optical microscope. Simultaneously, the phylogenetic analyses were performed by maximum likelihood and Bayesian inference methods based on a combined dataset of nrITS1-nr5.8S-nrITS2-nrLSU sequences. Integrated analysis of these results was therefore, G. efibulatus belonging to sect. Androsacei, G. iodes and G. sinopolyphyllus belonging to sect. Impudicae and G. strigosipes belonging to sect. Levipedes are proposed as new to science. The detailed descriptions, colour photos of basidiomata and line-drawings of microscopic structures are provided. The comparisons with closely related species and a key to known species of Gymnopus s. str. reported with morpho-molecular evidence in China is also given.

A new species of Gymnopus sect. Androsacei, namely, G. pallipes is described and illustrated based on morphological and molecular phylogenetic evidence. It is characterized by marasmioid basidiomata, a dark brown to reddish brown pileus becoming dull white to yellowish grey with age, whitish to pale yellow stipe and presence of rhizomorphs. Phylogenetic analyses support it as a new species within Gymnopus sect. Androsacei. The detailed morphological description, colour photos of basidiomata, and line drawings of microcharacters are presented and delimitation characters from similar species are discussed. A key to the known species of Gymnopus s. str. from China is also provided.

Based on phylogenetic analyses, some newly studied Chinese mushroom specimens were found to represent two distinct species within the genus Gymnopus. Along with G. fusipes (sect. Gymnopus) they form a distinct clade with high support, although their macromorphological characters seem to be closer to members of Gymnopus sect. Levipedes or sect. Vestipedes (Collybiopsis). When examined in detail, their micromorphological characters, especially the type of pileipellis, support them as new members of G. sect. Gymnopus. Therefore, two new species, G. omphalinoides and G. schizophyllus, and the emended circumscription of sect. Gymnopus are proposed in this paper. Detailed morphological descriptions, colour photos, illustrations of the two new species, morphological comparisons with similar taxa and the molecular-phylogenetic analyses of the combined nrITS and nrLSU data are presented. A key to the known species of G. sect. Gymnopus is also presented.

Pluteus losulus is reported as a new record from China. It is characterized by its low umbo with brown to grayish-brown pileus, hooked and metuloid pleurocystidia, variable cheilocystidia, presence of caulocystidia, and frequent presence of clamp connections in the pileipellis. New data from the nuclear ribosomal internal transcribed spacer (ITS) region place this species in a sub-basal clade of P. sect. Pluteus. A morphological description, illustrations, and phylogenetic placement of the Chinese P. losulus collection are provided.

Gymnopus pseudoandrosaceus sp. nov. is described from Southwest China. It is characterized by a brown marasmioid pileus, a shining black stipe, and abundant rhizomorphs, a pileipellis in the form of a cutis with encrusted pigments and without broom cells, and cheilocystidia with apical projections. The phylogenetic analysis placed the new species within the Gymnopus sect. Androsacei clade with well-supported lineages across Impudicae, Levipedes, Gymnopus, Androsacei, and Paragymnopus. Strong bootstrap values affirm these relationships, with notable diversity in Gymnopus indicating potential adaptive radiation. The pileipellis lacking broom cells is a rather unique feature in this section. Detailed morphological descriptions, basidiomata photographs, microscopic structure images, and phylogenetic analysis results are provided.