Lyophyllum sinense S. M. Tang & S. H. Li sp. nov.

Figs 7 A, B, 8, 9

Etymology.

The epithet “ sinense ” refers to the country “ China, ” where this fungus was first discovered.

Holotype.

China • Yunnan Province: Chuxiong Prefecture, Wuding County, elev. 2,119 m, 6 September 2023, Song-Ming Tang, L 5090 (HKAS 144417!).

Description.

Pileus 2.0–3.0 cm diameter, fleshy, fragile, hemispherical, becoming convex with age, abundant black floccus on the surface, dry, dark grayish orange (# a 4 a 3 a 0) on the center, grayish yellow (# cac 4 b 0) with margin, slightly depressed of center, involute of margin; pileus context thick, 0.3–0.5 cm wide, white (# fcfcfc). Lamellae moderately close together, arcuate, subdecurrent to decurrent, broad, white (# fcfcfc), grey dark orange (# a 4 a 3 a 0) when injured, 3–4 tiers, 0.3–0.4 cm wide, edge even or entire. Stipe 3.0–4.0 × 0.9–1.8 cm, cylindrical to clavate, dark grayish orange (# a 4 a 3 a 0) points and lines on the surface, bulbous at the base, smooth; stipe context white (# fcfcfc), changing to grayish orange (# c 2 bbab) when injured. The odor and taste were not distinctive.

Basidiospores [68 / 2 / 2] 6.1–8.6 × 5.5–7.1 μm, (Q = 1.0–1.3, Qm = 1.21 ± 0.12), av. 7.28 ± 0.68 × 6.07 ± 0.62 μm, quadrangular to very broadly fusiform, hyaline, smooth. Basidia 28–41 × 8–10 μm (N = 20), av. 34.6 ± 4.0 × 9.5 ± 0.53 μm, mostly 4 - spored, rarely 2 - spored, sterigmata long 2.2–3.9 μm, sometimes with basal clamp connections, clavate, siderophilous granulations. Subhymenium is composed of moderately thin-walled hyphae, 40–60 μm thick, with 2–3 layers of ovoid, fusiform to narrowly cylindrical hyphae, 5–7 × 2–4 μm. Hymenophoral trama regular, 130–180 μm wide, consisting of thin and hyaline hyphae, some with clamp connections, narrowly cylindrical hyphal elements, 4–7 μm wide. Cheilocystidia were 14–23 × 3–5 μm, av. 17.6 ± 2.4 × 4.1 ± 0.7 μm, narrowly cylindrical or narrowly clavate, thin-walled. Pleurocystidia were 10–25 × 3–6 μm in size and av. 17.2 ± 3.2 × 4.3 ± 1.1 μm, narrowly cylindrical or narrowly clavate, thin-walled. Pileipellis colorless and hyaline in 5 % KOH solution, parallel, thin-walled, almost cylindrical to subcylindrical, filamentous hyphae 2–3 μm wide. Stipitipellis composed of appressed, parallel, thin-walled, hyphae 2–4 µm wide. Clamp connections are present at some septa in the pileipellis, lamellae, and stipitipellis.

Habitat.

Clustered in native forests in Yunnan, associated with Lithocarpus sp., at the base of the trees.

Edibility.

This species is an edible mushroom found in the Yunnan Province.

Additional species examined.

China • Yunnan Province, Chuxiong Prefecture, Wuding County, elev. 2,120 m, September 18, 2023, Song-Ming Tang, paratype, L 5016, HKAS 144418.

Notes.

Morphologically, L. sinense is similar to L. rhombisporum and L. subalpinarum, with quadrangular to very broad fusiforms. However, L. rhombisporum has relatively longer cheilocystidia (28–40 × 5–8 µm) and pleurocystidia (20–46 × 4–6 µm) (Li et al. 2023). Lyophyllum subalpinarum, which lacks cheilocystidia and pleurocystidia, has a grayish-yellow pileus and hollow stipe (Wei et al. 2023).

In our multi-locus phylogeny, L. sinense was found to be closely related to L. bulborhizum and L. nigrum. However, L. bulborhizum, mostly solitary, has a relatively bulbous at the stipe base; stipitipellis has abundant caulocystidia on the surface (Li et al. 2023). The ITS sequence difference between L. sinense (L 5090, holotype) and L. bulborhizum (L 5083, holotype) was 1.99 % (11 / 552, not including gaps). Lyophyllum nigrum has relatively narrower lamellae (0.1–0.2 cm) and abundant caulocystidia on its surface (Li et al. 2023); the ITS sequence difference between L. nigrum (L 5091, holotype) and L. sinense (L 5090, holotype) was 3.62 % (20 / 552, not including gaps).