Gymnopus biyangensis J. J. Hu, B. Zhang, X. Li & Y. Li 2025, sp. nov.

Gymnopus biyangensis J. J. Hu, B. Zhang, X. Li & Y. Li sp. nov. Figs 2 A, 3 Etymology. Refers to the location of type material. Diagnosis. [English] This species is characterized by the basidiomata that appear in summer and originate from broad-leaved forests, dark reddish-brown pileus, cylindrical to clavate stipe, clavate to cylindrical cheilocystidia with a narrowly protruding apex. Type. China. Henan Province • Zhumadian City, Biyang County, Mingzhuang Village, 10 July 2021, Jia-Jun Hu, Bo Zhang, and Xiao Li, ZNU-F -001 (Collection No.: Hu 769), holotype. Description. Basidiomata medium-sized. Pileus 3.3–4.4 cm in diameter, applanate-convex, reddish brown to brown, smooth, glabrous; margin entire, wavy to upturned, dark reddish-brown to light brown. Context thin, yellow to light brown, freshy, odorless. Stipe 2.0–5.0 cm long and 0.5–1.3 cm wide, central, cylindrical to clavate, smooth, light yellow, occasionally with reddish brown tones or slight spots at the base. Lamellae adnate to adnexed, close, yellowish brown to light brown, unequal. Occurrence in leaf litter. Basidiospores 5.0–6.0 × 3.0–4.0 µm, Q = (1.25) 1.30–1.93, Qm = 1.64 ± 0.19, elliptic, hyaline, smooth, inamyloid, thin-walled. Basidia (12) 16–23 × 3–6 µm, clavate to cylindrical, 2 - or 4 - spored, hyaline, smooth, thin-walled. Cheilocystidia (16) 17–28 (29) × 3–6 µm, cylindrical to clavate with mamiform, often longer apical projections, less commonly weakly coralloid, hyaline, smooth, thin-walled. Pleurocystidia and caulocystidia not observed. Pileipellis a “ dryophila - type ” cutis, 8–14 µm wide, hyaline, smooth, thin-walled. Clamp connections present in all tissues. Habit, habitat, and distribution. Scattered to gregarious. Saprotrophic, with humicolous habitat, found in broad-leaved forests. So far, it is only known from Henan Province, China. Other specimens examined. China. Henan Province • Zhumadian City, Biyang County, Mingzhuang Village, 10 July 2021, Jia-Jun Hu, Bo Zhang, and Xiao Li, ZNU-F -002 (Collection No.: Hu 770) • Zhumadian City, Biyang County, Mingzhuang Village, 10 July 2022, Jia-Jun Hu, Bo Zhang, and Xiao Li, ZNU-F -003 (Collection No.: Hu 775). Note. This species is characterized by the basidiomata occurring in the summer, a dark reddish-brown pileus, a cylindrical to clavate stipe, an apex of cheilocystidia that is not diverticulate or lobate. Gymnopus biyangensis is similar to species in the G. erythropus complex due to the dark reddish-brown pileus. However, this species differs from G. erythropus by the light yellow and cylindrical to clavate stipe, smaller basidiospores, and a non-encrusted pileipellis. Gymnopus biyangensis can be distinguished from G. fagiphilus by the smooth and light-yellow stipe and smaller basidiospores.