Species diversity of edible mushrooms IV: Morphology and phylogenetic analysis reveal two new species of Lyophyllum (Lyophyllaceae, Basidiomycota) from Yunnan Province, Southwestern China

Lyophyllum species holds significant economic and medicinal value. During an investigation of macrofungi in southwestern China, seven Lyophyllum specimens were collected. Detailed morphological examinations, together with multi-locus phylogenetic analyses based on internal transcribed spacer (ITS), nuclear ribosomal large subunit (nrLSU), RNA polymerase II second largest subunit (rpb 2), and translation elongation factor 1 - alpha (tef 1 - α) sequence data, revealed two previously undescribed species, Lyophyllum hemigaleatum and L. pseudorrhizum.

Lyophyllum hemigaleatum has an orange and hemispherical pileus (1.4–1.8 cm), inflexed of margin; pileus context white, fleshy, and turns slightly desaturated orange when injured; basidiospores broadly to subbroadly (av. 7.36 ± 0.65 × 5.10 ± 0.44 μm); in multi-locus phylogenetic analysis, Lyophyllum hemigaleatum is closely related to L. semitale, L. semitale was originally described from Sweden, has a larger pileus (2.5 cm vs. 1.4–1.8 cm) and a white stipe; its most distinctive feature is a distinctly rooted stipe and saprophytic on wood, these pieces of evidence support our tentative identification of L. hemigaleatum as new species.

Lyophyllum pseudorrhizum is characterised by a fleshy pileus (1.2–2.8 cm wide) that is greyish orange, hemispherical when young, becoming plano-convex or convex with age and with an inflexed margin; pileus context is white and unchanged in colour when injured; stipe base aggregates to form pseudorrhiza; basidiospores subglobose to broadly ellipsoid (av. 5.2 ± 0.42 × 4.8 ± 0.34 μm). Descriptions, illustrations and phylogenetic analysis results of the new species are provided.

In addition, the new species are compared with closely related taxa.