Lepiota atrobrunneodisca L. Fan, L. Xia & N. Mao, 2023

Mao, Ning, Xia, Lu, Xu, Yu-Yan & Fan, Li, 2023, Lepiota atrobrunneodisca (Agaricaceae, Agaricales), a new species with a hymeniform pileus covering from North China, Phytotaxa 595 (2), pp. 186-198 : 194-195

Lepiota atrobrunneodisca L. Fan, L. Xia & N. Mao , sp. nov. ( Figs. 3 )

Mycobank:—MB846287

Diagnosis:—Most similar to L. neophana Morgan (1906: 248) but differs by the slightly larger basidiospores (5–7 × 3–4 μm), darker center of pileus and annulus often adhering to stipe, and the pileus surface that breaks up into squamules.

Etymology:—‘ atrobrunneodisca ’, refers to the pileus with dark brown central umbonate disc of this species.

Holotype:— CHINA. Shanxi Province, Wuzhai County, Guancenshan Mountains , 38°52’26’’N, 111°57’48’’E, 1,990 m elev., 1 August 2018, on the ground in coniferous forest dominated by Larix gmelinii var. principis-rupprechtii (Mayr) Pilger in Engler & Prantl (1926: 327), H. Liu ( HSA 115 ).

Description:— Basidiomes small to medium. Pileus 22–63 mm diam, hemispherical to obtusely conical when young, then expanding to convex, applanate with distinct umbo; surface dry, at first smooth, later irregularly cracking into squamules, not uplifted from surface, irregularly shaped, dark brown (#3f1010) to black brown (#2b0b0b) at center, brown (#7c4f1f) to pale yellow-brown (#cd8334) towards the margin on a whitish background. Lamellae close, l = 1–2, free, white (#ffffff); edge smooth, whiter. Stipe 55–80 × 4–6 mm, central, cylindrical, equal or sometimes slightly broadened at base, hollow, smooth, pale yellow-brown (#e6c19a) to pale white (#f2f2f2). Annulus cuff-like, cottony or membranous, white, attached at the upper part of stipe but easily falling off. Context concolorous with lamellae, but sometimes with pale pink shadow. Odor not recorded. Taste not recorded. Spore print white.

Basidiospores [25/2/2] 5–7 × 3–4 μm; [Q = (1.38–) 1.5–2.0, Q av = 1.73 ± 0.24]; in side-view ellipsoid to narrowly ellipsoid, with an acute apex, in front-view ovoid, binucleate, non-dextrinoid, reddish purple in cresyl blue, smooth, thin-walled, usually containing one droplet. Basidia 22–32 × 6–10 μm, hyaline, (2–)4-spored, clavate. Cheilocystidia numerous, 30–45 × 8–13 μm, most narrowly clavate, pyriform to almost sphaeropedunculate, hyaline. Pleurocystidia absent. Pileus covering a hymeniderm made up of tightly packed subglobose, sphaeropedunculate to clavate, terminal elements of different lengths, 28–65 × 11–25 µm, mostly 1-celled, but also 2–3-celled, with brownish intracellular pigment, slightly thick-walled. Clamp connections present in all tissues.

Habit and distribution:—solitary or scattered on the ground in coniferous forest dominated by Larix gmelinii var. principis-rupprechtii, Shanxi Province, China.

Additional specimen examined:— CHINA. Shanxi Province, Wutai County, Wutai Mountain , 38°57’58’’N, 113°30’60’’E, 2,086 m elev., 27 August 2019, on the ground in coniferous forest dominated by Larix gmelinii var. principis-rupprechtii, Y Shen ( BJTC FM889 ) .

Figures

FIGURE 3. Lepiota atrobrunneodisca (BJTC HSA 115, holotype). a. Basidiomes. b. Basidiospores. c Basidia. d Cheilocystidia. e Pileus covering. Scale bars: a = 10 mm; b = 2μm; c= 5μm; d, e = 10μm. Photos by: Li Fan.