Panaeolus ranwuensis M.Q. He, R.L. Zhao & B. Cao, in Cao et al., Fungal Diversity 132: 529 (2025)
Index Fungorum number: IF 572243; MycoBank number: MB 572243; Facesoffungi number: FoF 17110; Figs. 1, 2
Etymology – “ranwu” refers to Ranwu town, the locality of the type specimen.
Holotype – HMAS 287965.
Pileus 9.3–14.1 mm in diam., obtusely conic, campanulate, darkish olive (pantone 5747 c), sometimes paler at margin, surface dry, silk-like, smooth, margin uplifted when basidiomata is dry. Lamellae adnate, subdistant, broad, mottled grayish to blackish, entire, edge white. Stipe equal, hollow, 78.7–109.9 mm long, 2.0 mm thick, darkish olive, the same color as pileus (pantone 5747 c), lower surface paler, smooth, base with whitish mycelium.
Basidiospores 19.3–24.2 × 10.2–12.9 µm (x̄ = 21.2 ± 1.3 × 11.7 ± 0.9, Q = 1.7–1.8, Qm = 2.0 ± 0.1, n = 20), oblong, smooth, brown, blackish brown, protruding germ pore. Basidia 26.6–34.6 × 11.4–14.7 µm, 4-spored, smooth, hyaline. Cheilocystidia 14.5–37.0 × 4–14.2 µm, ventricose-rostrate, cylindrical, flexuous, hyaline, smooth. Pleurocystidia absent. Cuticle composed of large vesicles, pileocystidia 24.1–42.2 × 12.1–30.6 µm, pyriform, hyaline, some with brown pigment. Caulocystidia 17.0–33.9 × 3.5–6.9 µm, cylindrical, flexuose. Clamp connections present in all hyphae.
Material examined – CHINA, Inner Mongolia Autonomous Region, Aug 1994, Xiao-Lan Mao, You-Zhi Wang, HMAS 69910; Xizang Autonomous Region, Qamdo Municipality, Baxoi County, 29°47’37″N 95°53’20″E, 2870 m alt, 23 July 2021, Mao-Qiang He, Zhi-lin Ling, ZRL20210707 (HMAS 287965, holotype).
GenBank – HMAS 287965: PP475220 (ITS), PP472785 (LSU), PP556788 (tef1), PP850966 (rpb1), PP852735 (rpb2), PP472894 (SSU); HMAS 69910: PP475221 (ITS), PP472781 (LSU), PP556789 (tef1), PP852734 (rpb2).
Notes – Panaeolus ranwuensis, represented by HMAS 69910 and HMAS 287965, is clustered in Panaeolus with statistical supports as BS/PP = 63/0.95. The sister species is P. alcis, represented by a sample collected from Sweden (Mushroom Observer 88,085). Compared with P. alcis, P. ranwuensis has olive pileus, while P. alcis is pale gray. In addition, the pleurocystidia is absent in P. alcis (Moser 1984).
Figure 1 – Panaeolus ranwuensis. a Basidiomata in the field (HMAS 287965, holotype). b Old specimen deposited in HMAS (HMAS 69910). c Pileocystidia. d Caulocystidia. e Basidiospores. f Cheilocystidia. g Basidia. Scale bars: e = 10 µm, c, d, f, g = 20 µm.
Figure 2 – Maximum Likelihood tree of Galeropsidacea based on six-genes (ITS, LSU, tef1, rpb1, rpb2, and SSU) with outgroup species from Bolbitiaceae.