细环黄蘑菇Agaricus necopinatus

描述1 描述来源：Two new species of Xanthagaricus and some notes on Heinemannomyces from Asia
类型：简短的描述（摘录自图鉴等，请注意甄别描述真实性）
描述原文：
Xanthagaricus necopinatus Iqbal Hosen, T.H. Li, & G.M. Gates, sp. nov. MycoBank: MB822731 Figs 2c, d, 4, 5b
Diagnosis. Morphologically similar to X. flavosquamosus but differs in the presence of a fugacious annulus, smaller and denser squamules, comparatively smaller basidiospores with rugulose-rough surface, clavate to narrowly clavate cheilocystidia.
Typification. BANGLADESH, Dhaka Division, Sher-e-Bangla Nagar, Chondrima Uddan, 21 Aug 2014, Iqbal 821 (GDGM 46632, holotype; PHI-12, isotype).
Etymology. The species epithet “necopinatus” (Lat.) means unexpected, refers to the unexpected, surprising habitat of the collection, which was found on a concrete wall.
Description. Basidiomata small-sized. Pileus 10–15 mm broad, hemispherical, convex to plano-convex, yellow (2A4–7) to vivid yellow (2A8), maize yellow (4A6), light olive yellow (3D3–4) to pale brown (5D4) at disc, with yellow (3A4) to yellowish brown (5D8, 5E8) squamulose or finely fibrillose squamules on the surface, more concentrated and darker at center but scattered elsewhere; margin incurved with appendiculate velar remnants, concolorous with the pileus squamules; context 0.7 mm thick at pileus center, elsewhere thin, unchanged when cut or injured. Lamellae free, depressed around the stipe, yellowish white (3A2) to pinkish white (10A2), light brownish gray (6C3, 6D3), with crenulate edge, broadly ventricose; lamellulae commonly with 3–4 tiers. Stipe 18–28 × 1.5–2 mm, equal to slightly attenuated towards base, central, cylindrical, slightly curved, fistulose, yellowish brown (5D4) to dull brown (5C2), with some scattered squamules on surface; squamules more concentrated toward apex. Annulus very thin and tiny, superior, fugacious, often gone due to handling or with age. Odor and taste unknown.
Basidiospores [60/3/1] 4–5 × 2.7–3.2 μm, [mean length = 4.45 μm, mean width= 2.98 μm, Q = (1.31–)1.41–1.64(–1.72), Q m = 1.49 ± 0.064], ellipsoid to ovoid-ellipsoid, slightly thick-walled (0.5 μm), inamyloid, smooth under light microscope but rugulose-rough surface under SEM, yellow to yellowish brown in H 2 O and 5% KOH. Basidia 13–17 × 5–6 μm, clavate to narrowly clavate, pale yellow in H 2 O, thin-walled, 4-spored, with sterigmata up to 2 μm long. Lamellar trama regular to subregular, composed of thin-walled cylindrical hyphae, 4–8 μm wide. Cheilocystidia 15–20 × 4–6 μm, abundant, clavate to narrowly clavate, sometimes narrowly fusoid, smooth, hyaline, thin-walled. Pleurocystidia absent. Pileipellis (squamules on pileus) epithelial, composed of agglutinated globose, subglobose to broadly ellipsoid, rarely clavate cells, terminal cells measuring 9–15 × 6–10 μm, slightly encrusted, with some vacuolar pigments when observed in KOH or H 2 O. Caulocystidia sometimes present, cylindro-clavate to narrowly clavate measuring 18–25 × 5–7 μm, thin-walled, smooth, hyaline. Stipe trama composed of parallel hyphae 4–10 μm wide, yellowish brown in mass but pale yellow to subhyaline individually. Clamp connections absent in all tissues.
Habit, habitat and distribution. Scattered, clustered on a concrete wall, currently only known from Bangladesh.