Amanita alboumbelliformis - Amanitaceae.org - Taxonomy and Morphology of Amanita and Limacella
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name Amanita alboumbelliformis
name status nomen acceptum
author Yang-Yang Cui, Qing Cai & Zhu L. Yang.
english name "White Parasol Caesar"
intro This text is derived from the original description of Amanita alboumbelliformis.   The fruiting bodies of Amanita alboumbelliformis are medium-sized to large.
cap The cap is 70 – 100 mm wide, plano-convex to planar, sometimes raised over the stem (umbonate, white, but cream at center.  The cap’s margin is radially grooved (ca. 0.3 – 0.4 R), and there is not material hanging from the margin.  The flesh is white.
gills The gills are free, crowded, and white.  The short gills are truncate and plentiful.
stem The stem is 120 – 160 × 15 – 20 mm, nearly cylindric or narrowing upwards; its surface is white, covered with white to cream fibrils; the stem lacks a basal bulb.  At the stem's base, there is a saccate volva with a white outer layer.  The volva measures 50 – 80 × 40 – 50 mm, is membranous and has an inner surface is that is white to grayish.  The ring is skirt-like, white when young, but becoming yellow when mature.
odor/taste The odor and taste of the present species were not recorded.
spores The spores measure 9.0 – 11.0 × 9.0 – 11.0 µm and are globose to subglobose and inamyloid.  Clamps are common at bases of basidia.
discussion Amanita alboumbelliformis corresponds to A. cf. chepangiana in Yang (2015).  This species occurs in mixed subtropical forests in southwestern and southern China. 

The white fruiting body of A. alboumbelliformis calls mind to A. chepangiana Tulloss & Bhandary. However, A. chepangiana has relatively shorter grooves on the cap’s margin (about 20-30% of the cap's radius).  The stem bears a fragile, white ring.  The spores measure 9.5 – 12.5 × 8.5 – 11.5 µm and are subglobose to broadly ellipsoid.—Yang-Yang Cui and Rachel Warner
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