Leucoagaricus tangerinus Y. Yuan & J. F. Liang
MycoBank number: MB805472
Basidiomata small to medium Pileus 20–50 mm in diam., when young subcampanulate, expanding to applanate or convex, with low umbo; surface brownish orange (6C8) at the center, elsewhere corn (4A5) to light orange (5A5), with light orange, oxide yellow to brownish yellow (5A5–5C8) radially fibrillose squamules; margin slightly cracking when mature, with white floccose velar remnants at the margin, sometimes exceeding lamellae. Context white, thin, fragile. Lamellae L = 90–100, l = 8–12, free, moderately crowded, remote from the stipe, off-white, on average 2 mm wide. Stipe 65–70 × 3–4 mm, cylindrical, and slightly inflated at base (6 mm), hollow, white above annulus, below annulus off-white to yellowish white (2A2) or brownish yellow (5A5) with fine concolourous squamules, covered with colourless drops at lower part of stipe. Annulus small, ascending, membranous, white and fugacious. Odour not distinctive. Taste not recorded.
Basidiospores [80/4/4] (6.0) 6.5–7.0 (7.5) × 4.0–4.5 μm [Q = (1.40) 1.50–1.70 (1.75), avQ = 1.60 ± 0.11], ellipsoid to oblong in side view, oblong or slightly ellipsoid in frontal view, with a small hilar appendage, and blunt-rounded apex, without suprahilar depression and germ pore, hyaline, colourless, smooth, slightly thick-walled, dextrinoid, congophilous, metachromatic in Cresyl Blue. Basidia 16.0–26.0 × 7.0–10.0 μm, with two or four sterigmata, clavate. Cheilocystidia 25.0–60.0 × 8.0–15.0 μm, narrowly clavate to subfusiform, some subutriform, some narrowed at apex, hyaline, colourless, and sparse on the lamellae edge. Pleurocystidia 21.5–39.5 × 14.0–22.0 μm, variable in shape from broadly subutriform to pyriform, colourless, rare and not present in all specimens. Pileus covering a cutis of relatively loosely, radially arranged cylindrical hyphae, sometimes branched; terminal elements 70–230 × 8.0–9.0 μm, not evidently differentiated, subcylindrical and with slightly rounded apex, with pale yellow intracellular pigment. Clamp connections absent.
Habitat and distribution: Solitary to dispersed, not in small groups or in clusters, saprotrophic and terrestrial in broad-leaved forests, in summer. So far only found in southern China.
Additional specimens examined: CHINA, Fujian Prov., Sanming, Geshikao Nature Reserve. Alt 260 m, 24 Aug. 2007, P. Zhang 623 (HKAS52695) (GenBank KF501436); Xiamen, Xiaoping Forest Park, Alt 500 m, 10 Sept. 2011, X. F. Shi 937 (RITF2278) (GenBank KF981790); Guangdong Prov., Guangzhou, South China Botanical Garden, Alt 70 m, 13 Apr. 2012, J. F. Liang (RITF2279) (GenBank KF981791).
Fig. 1 One of 100 RAxML likelihood trees (–In L 7671.892950) based on the ITS dataset. Support values in bold type are RAxML likelihood bootstrap (≥75 %). Values in normal type are Bayesian posterior probabilities (≥0.95).
Fig 2. Basidiomata of Leucoagaricus tangerines (Holotype). Photo by Ping Zhang.
Fig. 3 Leucoagaricus tangerinus (Holotype). a Basidiomata; b Basidiospores; c Cheilocystidia; d Pleurocystidia; e Pileus covering.