Amanita sinocitrina

The fruiting bodies of A. sinocitrina are small to medium-sized.  The cap is 40-60 mm wide, convex to applanate, gray-yellow, sometimes brownish, with indistinct, innate, radial fibrils.  It is covered with grey to brownish, verrucose to floccose, felty, volval patches; its flesh is white, but turns brownish when exposed, especially in the bulb.

The gills of this species are free to subfree, crowded, white to cream-colored; and the short gills are attenuate and of diverse lengths

The stipe is 60 - 90 × 5 - 10 mm, subcylindric to attenuate upwards; its surface is white to dirty white, covered with yellowish to yellow squamules above the annulus, and with whitish to grayish squamules or fibrils below the annulus; the stipe's basal bulb is 15 - 25 mm wide, subabrupt to abrupt, marginate, with the upper margin covered with grayish to brownish, verrucose to floccose volval remnants..  The annulus is membranous and superior to nearly medium, with its upper surface cream-colored to yellowish and lower surface whitish to grayish or brownish.

Spores of A. sinocitrina measure (5.5) 6.0 - 7.5 (8.0) × (5.0) 5.5 - 7.0 (7.5) µm and are globose to subglobose, and amyloid.  Clamps are not present on the bases of basidia.

Amanita sinocitrina was originally described from central China.  It occurs in mixed forests with broad-leaved trees and conifers.  Its distribution range is still unknown.

Amanita sinocitrina is characterised by its small to medium-sized basidiome with a gray-yellow pileus, grey to brownish volval remnants, a whitish to yellowish annulus, a subabrupt to abrupt, marginate bulb on the base of the stipe, and small basidia and spores.  It is related to taxa such as A. bulbosa var. citrina (Schaeff.) Gillet [≡A. citrina (Schaeff.) Pers. non Gunnerus] and A. bulbosa var. bulbosa (Schaeff.) Lam. [=A. citrina var. alba (Quél.) E.-J. Gilbert].  However, A. sinocitrina differs from the European A. citrina by its differently colored pileus with somewhat darker colored volval remnants, smaller basidia and significantly smaller spores.

Amanita sinocitrina is also similar to A. citrina var. grisea (Hongo) Hongo, A. citrina f. lavendula (Coker) Veselý, A. brunnescens G. F. Atk. var. brunnescens (=A. brunnescens var. pallida L. Krieg.), A. brunnescens f. straminea E.-J. Gilbert (=A. citrina sensu auct. amer. orient.), A. aestivalis Singer ex Singer and A. asteropus Sabo ex Romagn.  However, A. citrina var. grisea, described from Japan, has a darker colored pileus, pallid yellow annulus, larger basidia and larger spores. Amanita citrina f. lavendula, originally described from the U.S., is distinguished from A. sinocitrina by, among others features, its differently colored pileus with lavender staining fruiting body and somewhat smaller spores.  Amanita brunnescens from eastern North America usually has larger basidiomes with umbrinous brown, innate radial striations or fibrils on the pileus covered with whitish to pallid volval remnants, a white stipe with a usually longitudinally cleft bulb, longer basidia, and larger spores.  Amanita brunnescens f. straminea has a differently colored pileus and stipe, and larger spores.  Amanita brunnescens var. pallida and A. aestivalis, both described from eastern North America, have a paler colored pileus, a longitudinally splitting bulb, larger basidia and larger spores.  Amanita asteropus, described from Europe, has a differently colored pileus with differently colored volval remnants, and without innate, radial fibrils, a longitudinally splitting bulb, trama or surface of stipe turning rapidly brown-orange when injured, and larger spores.—Zhu L. Yang

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