Leucoagaricus bailangshanensis J. Z. Xu, 2025

Zhang, An-Qi, Jin, Ri, Zhang, Xue-chao, Tarafder, Entaj & Xu, Ji-Ze, 2025, Two new species of genus Leucoagaricus and Leucocoprinus (Agaricaceae, Agaricales) from China, MycoKeys 125, pp. 33-49 : 33-49

Leucoagaricus bailangshanensis J. Z. Xu sp. nov.

Fig. 2

Diagnosis.

Leucoagaricus bailangshanensis differs from La. centrobrunneolus by pileus margin with floccules, longer sterigmata (3.5 µm), and distinctive ITS, nrLSU, rpb 2, and tef 1 - α sequences and position in the phylogram.

Holotype.

China • Liaoning Province, Huludao City, Bailangshan National Nature Reserve , on soil, 8 August 2023, J. Z. Xu ( HMJU 9098 , holotype) .

Etymology.

The epithet “ bailangshanensis ” refers to the location ‘ Bailang shan of Liaoning Province, where the holotype was collected.

Description.

Pileus 33–48 mm diam, ranging from plano-convex to convex, pale grayish-white to snow-white (28 B 1-28 A 1), with an irregular margin exhibiting remnants of the partial veil, surface arid, bearing imbricate squamules and radiating white fibrillose vestiges; umbo slightly obtuse, vinaceous yellow (4 B 4) centrally positioned, becoming radially fissured from the pileus center upon maturation. Context white, non-discoloring when bruised, thin. Lamellae free, cream-white (1 A 2) to white (1 A 1), crowded, less than 1 mm in width, with 1–3 tiers of lamellulae; edge entire. Stipe 41–54 × 3–5 mm, birch bark (6 B 2), hollow, covering white fibrillose. Annulus superior and single-layered white (1 A 1) on the upper stipe. Odor not distinctive. Spore print white.

Basidiospores [40 / 4 / 2] (3.6 –) 4.7–5.6 – 6.4 (– 6.9) × (2.8 –) 3.1–3.9 – 4.5 (– 4.8) µm, Q = 1.2–1.8, Qm = 1.40, broadly ellipsoid to slightly elongated, without a germ pore, transparent in 3 % KOH, dextrinoid, with 1 or 2 guttules. Basidia (12 –) 13–14.8 – 17 (– 17.7) × (5.0 –) 6.5–7.3 – 8.1 (– 8.7) µm, 2–4 spored, broadly clavate, hyaline in KOH; sterigmata up to 3.5 µm long. Cheilocystidia (23.1 –) 23.4–29.4 – 37.4 (– 39.4) × (7.3 –) 9.0–11.4 – 13.7 (– 15.0) μm, subfusiform to fusiform, smooth and hyaline KOH. Pleurocystidia absent. Lamellatrama regular, made up of parallel to subparallel, 2.6–8.1 μm wide hyphae in KOH. Pileipellis a cutis of repent, subcylindrical, radially arranged, occasionally branched, trichodermal, hyphae 3.6–14.2 wide. Clamp connections absent.

Habitat.

Solitary on soil in deciduous broadleaf forests.

Known distribution.

Known only from north-eastern China.

Additional material examined.

China • Liaoning Province, Huludao City, Bailangshan National Nature Reserve , on soil, 8 August 2023, J. Z. Xu ( HMJU 9304 ) ; China • Jilin Province, Jilin City, Zuojia Nature Reserve on soil, 22 September 2023, J. Z. Xu ( HMJU 9842 ) .

Notes.

The species is characterized by a pileus with a vinaceous, yellow umbo and white squamules radially arranged over a white background, crowded lamellae, a pileus margin with floccules, and cheilocystidia subfusiform to fusiform; and ITS, nrLSU, rpb 2, tef 1 - α sequence analyses, the present species clusters with members of the La. centrobrunneolus , signifying its position. Regarding overall morphology, the present specimen is quite similar to La. centrobrunneolus , La. lateritiopurpureus , La. Goossensiae Heinem , Leucoagaricus fuligineus Pegler , Leucoagaricus griseus Heinem , and La. luteocanus . However, La. centrobrunneolus has a much smaller pileus ( 20 mm) with its surface covered without floccules; smaller sterigmata (1.5 µm) ( Li et al. 2025). The pileus of La. lateritiopurpureus ( 10–20 mm) is covered with pink-brownish, brightly orange-brown, or terracotta scales, and much bigger basidia (20–25 × 7–10 µm) ( Malysheva et al. 2013). La. goossensiae and La. bailangshanensis differ in that the pileus is reddish-brown, smoother, and with radiating grooves; and the stipe is longer ( Heinemann 1973). Leucoagaricus fuligineus has a pileus the center of which is grayish-brown; the hyphae of the pileipellis are grayish-brown; basidia are bigger; and spores are concave ( Pegler 1977). Leucoagaricus griseus has a pileus, the center of which is dark gray, with much larger basidia and lanceolate cheilocystidia ( Heinemann 1979). Leucoagaricus luteocanus has a pileus the center of which is light brown, with radial light-brown to pale-yellow squamulose or fibrillose; the stipe has uneven brown coloration.

Figures

Figure 2. Leucoagaricus bailangshanensis (HMJU 9098, holotype). A, B. Basidiocarps; C. SEM images of basidiospores; D. Basidiospores; E. Basidia; F. Cheilocystidia; G. Pileipellis. Scale bar: 2 cm (A, B); 2 µm (C); 5 µm (D, E); 10 µm (F, G).