Species Diversity of Edible Mushrooms VI: Morphological and Phylogenetic Evidence Supports Five New Species of Laccaria (Hydnangiaceae, Agaricales) from China and Thailand

Laccaria is a cosmopolitan genus of ectomycorrhizal fungi that plays an important role in forest ecosystems worldwide. To explore the species diversity of Laccaria in Asia, this study conducted morphological observations and multi-gene phylogenetic analyses on 12 specimens collected from China and Thailand. The results showed that these 12 specimens formed five distinct and well-supported clades, which, combined with morphological comparisons, were recognized as five new species: L. aurantirufescens, L. bisporus, L. jilongensis, L. longicystidiata, and L. yadongensis. The main diagnostic characteristics of each new species are as follows: L. aurantirufescens has small to medium-sized basidiomata, an orange-red to russet pileus, and a yellowish-brown to reddish-brown stipe surface; L. bisporus has small basidiomata, a pale orange to orange-white pileus, and a brown to yellowish-brown stipe surface, and it possesses cheilocystidia, pleurocystidia, and caulocystidia; L. jilongensis has large basidiomata, with a pileus reaching up to 11 cm in diameter, orange-red coloration, sparse lamellae, a stipe up to 15 cm long, and the presence of cystidia; L. longicystidiata has small basidiomata, a pale orange to grayish-orange pileus, a light brown to brown stipe surface, and long cheilocystidia; L. yadongensis has small to medium-sized basidiomata, a pinkish-brown to fleshy-brown pileus that is darker at the center, four-spored basidia with sterigmata extending up to 10 μm in length, and a pileipellis composed of inflated hyphae, some of which exhibit brown pigmentation. These characteristics distinguish them from their closely related species. These findings not only enhance our understanding of Laccaria species diversity in Asia but also highlight the increasingly important role that Asia is poised to play in global fungal diversity conservation and taxonomic research.