Three new species of Mycena sect. Calodontes (Mycenaceae, Agaricales) from Northeastern China

Mycena sect. Calodontes is a large section within the genus Mycena, with 44 species described worldwide. The section is well characterized by relatively large basidiomata, typically growing on the humus layer of coniferous or coniferous-broadleaved mixed forests. Only 19 species of sect. Calodontes have been previously recorded in China, more than half of sect. Calodontes species are distributed in east and north regions, but also distributed in west and south regions. Based on 8 specimens collected from Heilongjiang and Jilin Province, 3 novel species are formally described: <i>M. brunneocystidiata</i> <b>sp. nov.</b>, <i>M. roseopurpurea</i> <b>sp. nov.</b>, and <i>M. rubrofusca</i> <b>sp. nov.</b> <i>Mycena brunneocystidiata</i> is distinguished by purple-brown to brown pileus, brown lamellae margins, and cystidia with brown contents. <i>Mycena roseopurpurea</i> is characterized by the pileus with brownish center, white lamellae margins, and colorless, fusiform cystidia. <i>Mycena rubrofusca</i> is distinguished by brownish pileus, white lamellae margins, and colorless, utriform cystidia. Detailed morphological descriptions, high-resolution habitat photographs, line drawings, and comparison with closely related taxa are provided for the new species. A combined phylogenetic analysis was conducted, based on a multi-locus (ITS+<i>RPB1</i>+<i>tef1</i>-<i>α</i>) dataset under Bayesian Inference (BI) and Maximum Likelihood (ML) analyses. The morphological data and the results of the phylogenetic analyses support the recognition of the 3 new species. A key to the 20 species currently known species of sect. Calodontes in China is also provided.