Panaeolus variabilicolor M. Q. He & R. L. Zhao, sp. nov.

Panaeolus variabilicolor M. Q. He & R. L. Zhao sp. nov. Fig. 14 Etymology. variabilicolor (Lat.) refers to several colors of basidiome are observed. Diagnosis. Panaeolus variabilicolor has hygrophanous or non-hygrophanous pileus, limoniform basidiospores, and cylindrical, clavate caulocystidia. Holotype. CHINA. Xizang Autonomous Region: Shigatse Municipality, Yadong County, 27.25.17°N, 88.56.32°E, alt. 3024 m, 26 July 2022, Mao-Qiang He, HMAS 287496 (ZRL 20220096). Description. Pileus 7.8–32.5 mm in diam., campanulate, conic, surface dry, hygrophanous, non-hygrophanous, color variable, gray (pantone 427 c), grayish black (pantone 412 c), light brown (pantone 166 c), reddish brown (pantone 7583 c), sometimes longitudinally striate near the margin, margin straight, uplifted, or decurved, occasionally with veil remnants. Lamellae adnate, close, entire, mottled grayish first then becoming blackish when mature, with a white edge. Stipe equal, hollow, 37.4–135.9 mm long, 1–2.7 mm thick, with some but darker color as pileus, smooth, slightly pruinose when basidiomes are fresh or young, base with whitish mycelium. Basidiospores 9.9–12.2 × 7.5–8.5 μm, [x = 10.7 ± 0.6 × 8.0 ± 0.3, Q = 1.2–1.4, Q m = 1.3 ± 0.1, n = 20], lager basidiospores were observed in ZRL 20220096 as 12.3–15.1 × 9.1–11.5 μm, [x = 14.1 ± 0.7 × 10.3 ± 0.7, Q = 1.3–1.5, Q m = 1.4 ± 0.1, n = 20], limoniform, blackish brown when mature, smooth, thick wall, germ pore distinctive. Basidia 18.2–27.2 × 7.0–10.1 μm, 4 - spored, smooth, hyaline. Cheilocystidia 15.4–34.8 × 3.8–8.2 μm, cylindrical with a slightly inflated apex and base, flexuose, hyaline, smooth. Pleurocystidia absent. Cuticle composed of large vesicles, pileocystidia not observed. Caulocystidia 12.9–53.8 × 4.2–7.8 μm, cylindrical, clavate. Habitat. Grows on fertile soil as pastures, grasslands, and forests, and on dungs. Psilocybin-producing. Nonproducing (ZRL 20220096, see Suppl. material 1: fig. S 9). Notes. Different basidiome colors were observed in P. variabilicolor. The variable basidiome color makes it difficult to distinguish this species in the field. For example, the basidiomes of ZRL 20210525 are orange brown and were found on dung in grassland. However, the basidiomes of ZRL 20220075 and ZRL 2022096 are grayish black and were found on soil in forest. Thus far, this species has only been found in the Xizang Autonomous Region. In the phylogenetic tree (Fig. 3), P. variabilicolor has a sister relationship with the clade composed of P. acuminatus and P. paludosus. Compared with these two species, P. variabilicolor can be easily distinguished by its relatively large basidiomes (7.8–32.5 mm in diam.). Specimens examined. China. Xizang Autonomous Region: Nyingchi Municipality, Chawalong, 28.33.44°N, 98.15.27°E, alt. 2670 m, 21 July 2021, Mao-Qiang He, ZRL 20210525; Shigatse Municipality, Yadong County, 27.25.17°N, 88.56.32°E, alt. 3024 m, 26 July 2022, Mao-Qiang He, ZRL 20220075, ZRL 20220205; Dinggyê County, 27.55.15°N, 87.21.37°E, alt. 3060 m, 29 July 2022, Dorji Phurbu, ZRL 20220144; Gyirong County, Gyirong Twon, 28.23.45°N, 85.23.34°E, alt. 3441 m, 2 August 2022, Jia-Xin Li, ZRL 20220735.