Index Fungorum number: IF 552903; Facesoffungi number: FoF2948
Pileus 16 mm, broadly convex with inflexed margin, covered with spine-like or pyramidal squamules over the whole surface, slightly crowded at center and more distant towards margin, squamules darker or yellowish-brown, light brown to golden-brown (5D5–8, 5E5–6) on grayish-yellow to greyish-orange (4B4–5, 5B4–5) fibrillose or floccose background; at marginal zone, fibrillose, concolorous with background. Lamellae white, free, ventricose, 1.5–2 mm wide, crowded, with white eroded edge. Stipe 38 × 2.5–3 mm, cylindrical or slightly wider at base and apex, covered with crowded fibrillose squamules from annular zone downward base, with squamules at basal zone, concolorous with those on pileus, with white to yellowish-white to pale yellow (4A2–3) fibrillose at annular zone upward from apex. Annulus an annular zone with fibrillose and fibrillose squamules as referred to on stipe. Context in pileus white, 3 mm wide; white and hollow in stipe. Taste and smell not observed. Spore print white. Basidiospores [25, 1, 1] 4–5 × 3–3.2 μm, avl × avw = 4.62 × 3.1 μm, Q = 1.33–1.56, avQ = 1.49, in side-view ellipsoid ovoid, in frontal view ellipsoid, hyaline, thin-walled, dextrinoid, congophilous, cyanophilous, not metachromatic. Basidia 20–26 × 5–6.5 μm, clavate, 4-spored, hyaline, thin-walled. Lamella edge sterile. Cheilocystidia 22–34 × 7–17 μm, mostly cylindrical, rarely narrowly clavate, hyaline, thin-walled, often branch and septate. Pleurocystidia absent. Pileus covering an epithelium made up of globose elements in lower layer (10–20 μm), with subglobose to oblong elements and often with subclavate elements in upper layer (8–32 × 5–20 μm, thick-walled, parietal and intracellular pigment in upper elements and parietal in lower elements. Stipe covering in squamules an epithelium similar to pileus covering. Clamp-connections present in all tissues.
Habitat and distribution: Growing solitary, on humus-rich soil with decaying leaves and wood in deciduous forest; only known from Mae Taeng District, Chiang Mai Province, Thailand. Material examined: THAILAND, Chiang Mai Province, Mae Taeng District, Forest of Pha Deng Village, N19°07′13.7″, E98°43′52.9″, alt. 905 m, 30 June 2011, P. Sysouphanthong (MFLU 12-2035, holotype).
Notes: All materials of Lepiota cylindrocystidia are recognized as having a yellow basidiomata, with cylindrical cheilocystidia.The ITS sequence data from the holotype clustered with species in sect. Echinatae and related to, but distinct from species with ovoid basidiospores.
Fig. 1 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