Fruiting bodies of A. atrofusca are
medium-sized. The cap is 60 - 100 mm wide, obtusely
umbonate, dark brown, often with a darker colored
ring-like zone at the inner end of the marginal
striations, and glabrous. The cap's margin is
tuberculate-striate (20% - 30% of radius) and
non-appendiculate; and the cap's context is white to dirty white.
The gills are whitish to greyish,
with brown to brownish edges; and the short gills are truncate.
The exannulate stem is 120 - 150 x
8 - 13 mm, subcylindric or slightly attenuate upwards,
fistulose, and with its surface densely covered with dark
brown, furfuraceous squamules; the stipe lacks a basal
bulb. At the stipe's base, the volva is saccate, with its
outer surface whitish to brownish and decorated with
brownish spots, and with its inner surface brownish.
The spores measure (9.5-) 11.0 - 14.5 (-15.0) × (8.5-) 11.0 - 14.5 (-15.0) µm and are
globose to subglobose and inamyloid. Clamps are absent from the bases of basidia.
Amanita atrofusca was described from China, and it is not uncommon in subalpine
to alpine regions of southwestern China.—Zhu L. Yang
Zhang et al. (2004), Key Lab. Biodivers. Biogeogr., Kunming Inst. Bot., Yunnan, China
The following text may make multiple use of each data field.
The field may contain magenta text presenting data from a type study
and/or revision of other original material cited in the protolog of the present taxon.
Macroscopic descriptions in magenta are a combination of data from the protolog and
additional observations made on the exiccata during revision of the cited original
The same field may also contain black text, which is data from a revision of the present
taxon (including non-type material and/or material not cited in the protolog).
Paragraphs of black text will be labeled if further subdivision of
this text is appropriate.
Olive text indicates a specimen that has not been
thoroughly examined (for example, for microscopic details) and marks other places in the text
where data is missing or uncertain.
The following material is entirely derived from the protolog of the present taxon.
NOTE: Spore measurements from papers by Z. L. Yang use his "Times New Roman" face for "Q" and "Q'"—respectively, "Q" and "Q."
Each spore data set is intended to comprise a set of measurements from a single specimen made by a single observer;
and explanations prepared for this site talk about specimen-observer pairs associated with each data set.
Combining more data into a single data set is non-optimal because it obscures observer differences
(which may be valuable for instructional purposes, for example) and may obscure instances in which
a single collection inadvertently contains a mixture of taxa.