Lepiota flavocarpa Sysouphanthong & K.D. Hyde

MycoBank number: MB 519962 Facesoffungi number: FoF 2949

Etymology: named because of its yellow basidiomata.

Holotype: MFLU 10-0581

Pileus 20–45 mm, convex at first, then umbonate with low umbo, applanate to plano-concave with straight margin, at center covered by crowded and large pyramidal warts, with or without recurred tips, and distant towards margin, dark yellow to yellowish-brown (4C8, 5D8), on yellow to vivid yellow (3A6–8), fibrillose back ground, when mature, trips of pyramids around margin fragile, pyramids becoming large squamules, and later fibrillose squamules; margin appendiculate with fibrillose or cortinate, concolorous with back ground or yellowish-white to pale yellow (1A2–3). Lamellae free, crowded, ventricose, 4–8 mm wide, concolorous with Pileus background, consistent, turning brownish-red to dark red (10C6–8) with KOH. Stipe 40–40 × 4–8 mm, cylindrical or slightly tapering to apex, background fibrillose, concolorous with Pileus, completely covered with crowded lanate flocculate or squamules from base upward to annular zone, then absent toward apex, at annular zone with concolorous fibrillose or cortinate as on Pileus margin. Annulus an annular zone, cortinate or fibrillose, yellowish-white to pale yellow (1A2–3). Context in Pileus concolorous with surface, up to 5 mm wide; in stipe concolorous with surface, hollow. Taste and smell not observed. Spore print white. Basidiospores [50, 2, 2] 4–4.5 × 3–3.2 μm, avl × avw = 4.24 × 3.1 μm, Q = 1.33–1.40, avQ = 1.36, in side-view ellipsoid ovoid, in frontal view ellipsoid, dextrinoid, congophilous, cyanophilous, not metachromatic in Cresyl Blue. Basidia 16–20 × 6–10 μm, narrowly clavate, 4-spored, hyaline to pale yellow-walled. Lamella edge sterile. Cheilocystidia 20–28 × 7–13 μm, clavate, fusiform or utriform, hyaline to pale yellow and thin-walled. Pleurocystidia absent. Pileus covering a sub hymeniderm or epithecium made up of agglutinate chains of mostly subglobose to oblong elements, 35–75 × 20–27 μm, sometimes globose, 18–25 μm, yellow to pale brown parietal and intracellular pigments. Stipe covering a sub hymeniderm made up of subglobose to oblong, 30–60 × 18–25 μm. Clamp connections present in all tissues.

Habitat and distribution: growing on a small group, on humus-rich soil mixed decayed leaves and branches; in deciduous forest dominated by Dipterocarpus and Castanopsis spp.; only found in rainy season (June to August) of Hui Kok Ma, Doi Suthep District, Chiang Mai, Thailand.

Material examined: THAILAND, Chiang Mai Province, Muang District, Hui Kok Ma od Doi Suthep, N 18 48′ 62”, E 98 54′ 60”, alt. 1145 m, 20 June 2010, P. Sysouphanthong, P63 (MFLU 10-0581, holotype); ibid., 18 June 2010, P. Sysouphanthong, P47 (MFLU 10-0565); ibid., 19 June 2010, P. Sysouphanthong, P50 (MFLU 10-0568); ibid., 27 August 2010, P. Sysouphanthong, P110 (MFLU 10-0628). GenBank number ITS:KP348285.

Notes: All material of Lepiota flavocarpa is recognized as having a yellow basidiomata, with dark yellow to yellowish-brown pyramidal squamules on the Pileus, turning brownish-red to dark red in KOH for whole basidiomata. The characters of ovoid Basidiospores and the subhymenidermal Pileus covering made up of globose to oblong elements located this species in sect. Echinatae. The ITS sequence data from the holotype clustered with species in sect. Echinatae and related to, but distinct from species with ovoid basidiospores.

Bayesian tree based on ITS sequence alignment of Lepiota species represent from each section. Support values from Bayesian posterior probabilities values (BYPP) more than 0.95 are given above tree branches, and bootstrap percentage more than 50% from maximum likelihood analyses are indicated below the tree branches. New sequences from Thailand are as bold. Agaricus bisporus and Clarkeinda trachodes are outgroup taxa.

Habits of Lepiota species in field. e L. flavocarpa.

Lepiota flavocarpa (MFLU 10-0581, holotype). a Basidiospores. b Basidia. c Cheilocystidia. d Pileus covering.