Panaeolus pallidus M. Q. He & R. L. Zhao sp. nov.

Fig. 11

Etymology.

pallidus (Lat.) refers to the white and light color of the basidiome.

Diagnosis.

Panaeolus pallidus has relatively large basidiomes with limoniform basidiospores and narrowly cylindrical, flexuose cheilocystidia.

Holotype.

CHINA. Gansu Province: Wuwei, Qilian Mountain National Nature Reserve, Haxi, 22 August 2018, Mao-Qiang He, HMAS 287494 (ZRL 20180988).

Description.

Pileus 17.3–73.6 mm in diam., hemispheric most, also could be plane when totally mature, disc slightly umbonate or flattened, gray (pantone warm gray 1 c), light brown (pantone 467 c), sometimes hygrophanous, surface dry, smooth, occasionally rugulose, margin slightly exceeding gills. Lamellae adnate, close, broad, mottled grayish to blackish, entire, with a white edge. Stipe equal, hollow, 91.8–147.4 mm long, 3.0– 5.4 mm thick, with the same color as pileus, smooth, pruinose, longitudinally striate, especially on the upper side, base with whitish mycelium.

Basidiospores 16.2–18.2 × 11.1–12.6 μm, [x = 17.2 ± 0.6 × 11.8 ± 0.4, Q = 1.4–1.5, Q m = 1.5 ± 0.0, n = 20], limoniform, blackish brown when mature, smooth, thick wall, germ pore distinctive. Basidia 24.6–40.6 × 10.7–15.3 μm, 4 - spored, smooth, hyaline. Cheilocystidia 36.0–61.3 × 4.6–11.4 μm, narrowly cylindrical, flexuose, with an inflated or globose head, hyaline, smooth. Pleurocystidia 29.0–33.7 × 11.1–13.6 μm, clavate to narrowly clavate, hyaline, smooth. Cuticle composed of large vesicles, pileocystidia 20.3–32.6 × 15.3–28.9 μm, spheropedunculate, hyaline. Caulocystidia 33.2–66.4 × 4.3–5.8 μm, cylindrical, rarely flexuose, hyaline, smooth.

Habitat.

Grows in pastures and on soil.

Psilocybin-producing property.

nonproducing (ZRL 20180988, see Suppl. material 1: fig. S 11).

Notes.

In the phylogenetic tree (Fig. 3), P. pallidus is placed in subclade A 1. The phylogenetically closest species are P. limoniformisporus and P. medogensis. Panaeolus pallidus was observed to have a plane pileus (observed in ZRL 20190137), which is rarely observed in Panaeolus. In the field, P. grandis resembles P. pallidus in having light-colored basidiomes, but the two species differ in cheilocystidia, with P. pallidus having narrowly cylindrical and flexuose cheilocystidia, whereas P. grandis has tibiiform cheilocystidia with an inflated base.

Specimen examined.

China. Beijing, Fangshan District, Baicaopan Nature Park, 01 August 2019, Rui-Lin Zhao, ZRL 20190137.