Morphology and phylogenetic analyses reveal two new species and a new record of Phaeocollybia (Agaricales, Hymenogastraceae) from southwestern China

Phaeocollybia is a globally distributed agaricoid genus and remains poorly studied in China. In this study, field surveys were conducted, and specimens of Phaeocollybia were collected in Yunnan Province and the Xizang Autonomous Region of southwestern China from 2024 to 2025. Based on detailed morphological observations and multilocus phylogenetic analyses using internal transcribed spacer (ITS), nuclear ribosomal large subunit (nrLSU), and second-largest subunit of RNA polymerase II ( rpb2 ) sequence data, two new species and one species newly recorded from China are recognized. Phaeocollybia dingjieensis is characterized by a paraboloid to broadly conical pileus with dark moderate orange vertical stripes, limoniform to amygdaliform basidiospores, and the presence of clamp connections. Phaeocollybia lulangensis is distinguished by a broadly conical to conical pileus with an oily to subwaxy luster, smooth to rarely verruculose basidiospores, and narrowly cylindrical to lageniform cheilocystidia with long rostrate apices. In addition, Phaeocollybia attenuata , previously known only from North America, is reported from China for the first time; its morphological variations and phylogenetic placement are documented. Phylogenetic analyses strongly support the delimitation of these taxa. Comprehensive morphological comparisons with related taxa are provided, and an updated dichotomous key to the 15 species of Phaeocollybia currently known from China is provided. These findings significantly expand the known diversity and distribution of Phaeocollybia in China.