Phylum:Basidiomycota >> Class: Basidiomycetes >>  Order: Agaricales 
 BCRC Number NO BCRC Number!  
 Scientific Name: Amanita yenii

Amanita yenii Zhu L. Yang & C. M. Chen, Mycotaxon 88: 455-462. 2003.

 Description: Basidiocarps medium-sized to large. Pileus 5-10 (12) cm in diameter, convex to applanate, white to whitish or dirty white, but cream-colored or pale yellowish over disc when young; volval remnants conical to subconical, 1-3 (4) mm high, 1-3 (4) mm wide, white to dirty white, occasionally brownish, especially towards apex, randomly arranged; margin smooth, appendiculate. Lamellae subfree to free, white when young, becoming cream-colored to yellowish when mature, crowded; lamellulae attenuate, evenly distributed. Stipe 6-12 × 0.5-1.5 cm, subcylindrical or tapering upwards, with apex slightly expanded, white, upper half often covered with white, recurving squamules, lower half glabrous or fibrillose; basal bulb clavate to subclavate or ventricose, 1-3 cm wide, non-marginate, with upper part nearly completely glabrous or covered with whitish to white, occasionally brownish, verrucose to subconical volval remnants, irregularly arranged or in incomplete concentric rings. Annulus pendant from attachment 0.5-1.5 (2) cm below apex of stipe, with upper surface cream-colored to yellowish, with lower surface white, thin, submembranous. Trama white, unchanging. Smell and taste indistinct. Lamellar trama bilateral. Mediostratum 30-50 μm wide, composed of fairly abundant to abundant long ellipsoid to clavate, inflated cells, mixed with abundant filamentous hyphae 3-7 μm wide, diverging at an angel of ca. 45∘to the mediostratum. Subhymenium 20-40 (50) μm thick, with 2-3 layers of subglobose to ovoid or ellipsoid to irregularly shaped inflated cells. Basidia 30-50 × 7-10 μm, clavate, 4-spored, occasionally 2-spored; sterigmata 3-4 (5) μm long; basal septa without clamps. Basidiospores (6.5) 7.5-10.0 (12.5) × (4.0) 4.5-6.5 (7.5) μm, Q = 1.55 ±0.15, ellipsoid to elongate, rarely broadly ellipsoid or cylindrical, amyloid, colorless, hyaline, thin-walled, smooth; apiculus small. Lamellar edge as sterile, incomplete strip up to 250 μm wide in side view, composed dominantly of subglobose to ovoid or broadly ellipsoid, inflated cells, single and terminal, or in chains of 2-3 (5) and then terminal, thin-walled, colorless, hyaline; filamentous hyphae 3-5 μm, scattered, irregularly arranged. Pileipellis hardly differentiated, composed of subradially arranged, filamentous hyphae up to 2-8 (12) μm wide, rarely gelatinized, colorless, hyaline, thin-walled to slightly thick-walled (up to 0.5 μm thick), surface of hyphae sometimes with refractive granular substances; vascular hyphae rare to locally conspicuous, 2-10 μm wide. Volval remnants on pileus composed of ±vertically, at volval base irregularly, arranged elements. Inflated cells very abundant to dominant, subglobose to ovoid (10-60 × 10-50 μm), sometimes ellipsoid (25-60 × 15-30 μm), often in chains of 2-4 and terminal, thin-walled to slightly thick-walled (up to 0.5 μm thick), colorless, hyaline; filamentous hyphae scattered to fairly abundant, somewhat more abundant in volval remnant base than elsewhere, 2-7 (12) μm wide, frequently branching and anastomosing, interwoven, thin-walled, colorless, hyaline; vascular hyphae rare, 2-10 μm wide. Volval remnants on upper part of basal bulb similar to those on pileus, but with filamentous hyphae somewhat more abundant and inflated cells often in shorter chains. Annulus composed of abundant to very abundant, clavate to broadly clavate or subglobose (17-40 × 15-30 μm) or ellipsoid (70-90 × 12-25 μm), colorless, hyaline, thin-walled, inflated cells; filamentous hyphae fairly abundant, loosely arranged, 2-7 μm wide, thin-walled, colorless, hyaline; vascular hyphae rare; upper surface of annulus gelatinized. Clamps not found.

Taiwan, Nantou: Hui-Sun Forest Experimental Station, alt.1850m, 10 Aug. 2000, Chen, CM. 2474; same location, 24 May 2001, Chen, CM. 2818. Sun Moon Lake, alt. 800m, 12 July 2000, Chen, CM.2414; same location, 5 Jun. 2002, Chen, CM. 3284; same location, 4 Sep. 2002, Chen, CM. 3570.

 Habitat: on ground in forests.

Taiwan, China (Hainan, Yunnan).


Yang ZL and Chen, CM. 2003.


C. M. Chen

 Note: In eastern Asia and southeastern Asia, A. yenii looks like A. virginea Massee and A. virgineoides Bas, originally described from Singapore and Japan respectively. However, A. virginea has a more robust basidiocarp with a more fugacious annulus, white to whitish lamellae, much wider basidiospores, and common clamps. A. virgineoides has a larger and stout basidiocarp with white to cream lamellae, thick annulus, wider basidiospores, and common clamps. In addition, the stipe of A. virgineoides is often covered with transversely arranged small squamules (Bas 1969, Imazeki et al. 1988, Yang 1997).