Hygrocybe flavomarginata (Agaricales, Basidiomycota), a New Species of Hygrocybe from China

Based on morphological and molecular phylogenetic analyses, we describe a new species, Hygrocybe flavomarginata, from the Tibetan Plateau, China. The internal transcribed spacer (ITS) and nuclear large subunit ribosomal DNA (nrLSU) sequences of the new species were divergent from those of related species in Hygrocybe (subgenus Pseudohygrocybe, section Coccineae, subsection Squamulosae). The divergence of H. flavomarginata from related Hygrocybe species was supported by high bootstrap support in the ML phylogenetic analysis of combined ITS and nrLSU sequences. H. flavomarginata is characterized by a small, hygrophanous pileus that is plane to slightly indented, orange with an orange-yellow margin, and a fibrillose-squamulose center. The lamellae are pale waxy yellow with orange-yellow edges, differing from those of related species by being convex rather than arcuate, and by extending beyond the pileus margin. Clamp connections are restricted to the pileus context and absent from both the lamellar trama and the stipitipellis.