Panaeolus papilionaceus Quel.

Panaeolus papilionaceus (Bull.) Quél., Mém. Soc. Émul. Montbéliard, Sér. 2 5: 152 [122 repr.] (1872) Fig. 15 Basionym. Agaricus papilionaceus Bull., Herb. Fr. (Paris) 1: 561 (1781). Description. Pileus 4–19 (– 49) mm in diam., conical to broadly conical, surface dry, smooth, occasionally hygrophanous, color variable, from gray (pantone 427 c), grayish olive (pantone 7536 c) to black (pantone 412 c), brown (pantone 7587 c) is also observed (in ZRL 20220358), usually paler at edge, margin entire, covered by white, triangular veil remnants. Lamellae adnate, close, broad, mottled grayish first then becoming blackish when mature, entire, with a white edge. Stipe equal, hollow, 13–140 mm long, up to 2 mm thick, always the same color as pileus, gray to black, dark purple, paler above, smooth, pruinose especially on the side close to the cap, occasionally with whitish mycelium. Basidiospores 15.7–18.3 × 9.6–12.4 μm, [x = 16.9 ± 0.6 × 11.5 ± 0.7, Q = 1.4–1.7, Q m = 1.3 ± 0.1, n = 20], limoniform, ellipsoid, blackish brown when mature, smooth, thick wall, protruding germ pore. Basidia 22.1–27.0 × 13.9–16.3 μm, 4 - spored, smooth, hyaline. Cheilocystidia 23.2–33.4 × 2.9–6.6 μm, cylindrical or narrowly clavate, flexuose, hyaline, smooth. Pleurocystidia absent. Cuticle composed of large vesicles, pileocystidia spheropedunculate, hyaline, some light brown, darker at the base. Caulocystidia 43.0–60.9 × 4.1–7.7 μm, cylindrical or narrowly clavate, flexuose, hyaline and light brown, smooth. Habitat. Grows in pastures, on dung of horses and cows. Psilocybin-producing. Nonproducing (ZRL 20210652, see Suppl. material 1: fig. S 4). Notes. Panaeolus papilionaceus is characterized by its small-sized basidiomes, a conical to broadly conical pileus, and limoniform basidiospores. An extremely small mature basidiome was observed in ZRL 20220202, in which the pileus is 4 mm in diam. and the stipe is 13 mm long. Specimens examined. China. Yunan Province: Dêqên Tibetan Autonomous Prefecture, Shangri-la City, 23 July 2012, collected by Rui-Lin Zhao, ZRL 2012412; Inner Mongolia Autonomous Region: Hulunbeier City, Lalantun, Chaihe Wildlife Natural Reserve, 47°32'44"N, 121°13'22"E, alt. 810 m, 27 August 2017, Zhilin Ling, ZRL 20170629; Xinbaerhuzuo County, 49°45'20"N, 120°12'9"E, alt. 510 m, 26 August 2017, Zhilin Ling, ZRL 20170653; Gansu Province: Wuwei, Tianzhu County, 19 August 2018, Bin Cao, ZRL 20181046; Beijing: Fangshan District, Baicaopan Nature Park, 1 August 2019, Rui-Lin Zhao, ZRL 20190135; Sichuan Province: Garze Tibetan Autonomous Prefecture, Litang County, 21 August 2019, Bin Cao, ZRL 20191490; Sichuan Province: Li County, 1 August 1958, Qionglin Hu, HMAS 23784; Jiuzhaigou, 9 June 1983, Huaan Wen, Jingjun Su, HMAS 51233; Xizang Autonomous Region: Nyingchi Municipality, Chawalong, 28.36.46°N, 98.5.22°E, alt. 4110 m, 21 July 2021, Mao-Qiang He, ZRL 20210652; Qamdo Municipality, Baxoi County, 29.47.37°N, 95.53.20°E, alt. 2870 m, 23 July 2021, Rui-Lin Zhao, ZRL 20210692, ZRL 20210750; Xizang Autonomous Region: Shigatse Municipality, Yadong County, 27.25.17°N, 88.56.32°E, alt. 3024 m, 26 July 2022, Mao-Qiang He, ZRL 20220092, ZRL 20220153, ZRL 20220201, ZRL 20220202, ZRL 20220203, ZRL 20220358; Gyirong County, 28.22.39°N, 85.19.40°E, alt. 2780 m, 2 nd August 2022, Jiaxin Li, ZRL 20220703; Ningxia Hui Autonomous Region, 24 August 1997, Huaan Wen, Suxiao Sun, HMAS 72699; Hubei Province: Shennongjia forestry district, Dajiuhu, 24 June 2023, Mao-Qiang He, ZRL 20230343.