The cap of A. merxmuelleri is 65 - 150 mm wide,
gray-brown to porphyry-brown, dull or subshiny, viscid in
humid conditions, hemispheric to convex when young, later campanulate
to planar with a rather depressed disc, with a nonstriate margin. The margin is decurved or slightly incurved at
first and sometimes bears hanging parts of the volva. The flesh is whitish. The
volva is present as irregularly distributed warts and small patches
and are polygonal, clod-like, thicker over the disc, thinner near the
margin, reddish-brown, cinnamon to ochre-brown, sometimes gray-brown.
The gills are free, crowded, whitish to
cream, becoming pale leather color, with the edge colorless at first
then becoming gray-brown to chestnut-brown. Short gills are present.
The stem is 75 - 150 × 18 - 45 mm,
narrowing upward, exannulate, with a mixture of lilac-tinted
colors when quite young, later whitish at apex and having a whitish
ground below decorated with gray-brown to porphyry-brown to
lilac-brown to wine-colored streaks or squamules. The bulb is white,
stuffed rather firmly, becoming slightly brownish after exposure to
air, pronounced in young material, but reduced to a swollen base of
then-clavate stem or only slightly broader than the stem in mature
material. The flesh is whitish, mostly unchanging on exposure to air,
but faintly browning in the base. The volva is present as a single ring of
fine warts at the meeting point of stem and bulb and is concolorous with
volva on the cap.
The odor is similar that that of raw
potatoes, and the taste is reported as similar to asparagus.
The spores measure (10.1-) 10.6 - 14.0 (-15.0) × (6.5-) 6.8 - 9.0 (-10.1)
µm and are ellipsoid to elongate, infrequently broadly ellipsoid and inamyloid. Clamps are
common at the bases of
The following have all been shown to be
absent from A. merxmuelleri: amanitins, phalloidin, muscimol,
A. merxmuelleri is present in association with Nothofagus pumilio.
According to Dr. Rolf Singer's notebooks (Field
Natur. Hist. Mus.) he collected material probably of this species on
which crassospores were plentiful. These unusual, malformed spores
with a surface suggesting the dimple on a golf ball have been noted in
other taxa collected in certain regions of the Argentine Andes (A.
morenoi Raithelh. and A.
This species may have been reported under
various other names in the past including A. umbrinolutea in the sense of Raithelhuber.
Due to delays in data processing at GenBank, some accession numbers may lead to dead pages.
These pages will eventually be made live, so try again later.
65–150 mm wide, gray-brown to porphyry-brown, hemispheric to convex when young, later campanulate to planar with rather depressed disc, dull or subshiny, viscid in humid conditions; context whitish; margin not striate, not pellucid, decurved or slightly incurved at first, sometimes bearing hanging bits of the veils; universal veil as irregularly distributed warts and small patches, polygonal, clod-like, thicker over disc, thinner near margin, reddish brown, cinnamon to ocher-brown, sometimes gray-brown (then more or less concolorous with the pileipellis).
free, crowded, whitish to cream, becoming pale leather color, with edge colorless at first then becoming gray-brown to chestnut brown; lamellulae present.
75–150 × 18–45 mm, with a mixture of lilac-tinted colors when quite young, later whitish at apex and having a whitish ground below decorated with gray-brown to porphyry-brown to lilac-brown to wine-colored streaks or squamules (in linear arrangement in younger specimens and becoming a similarly colored snakeskin pattern of colored fibrils in older ones), narrowing upward; bulb white, stuffed rather firmly, becoming slightly brownish after exposure to air, pronounced in young material, but reduced to swollen base of then clavate stipe or only slightly broader than stipe in mature material; context whitish, mostly unchanging on exposure to air, but faintly browning in base; exannulate; universal veil as single ring of fine warts at meeting point of stipe and bulb, colored as on pileus.
Odor close to raw potatoes; taste like asparagus.
10% KOH - negative; phenol - violet on pileipellis, stipe, and in context.
The following all failed to be detected from A. merxmuelleri by thin-layer chromatography (Garrido & Bresinsky 1985: 526): Muscimol, muscarin, amanitin, and phalloidin.
62–77 × 13–15 µm, ??-sterigmate, with sterigmata up to ?? × ?? µm; clamps common.
CHILE: MAGALLANES Y LA ANTARTICA—Punta Arenas, Rio las Minas, 7.iii.1984 A. Bresinsky & N. Garrido 26a (holotype, M n.v.; isotype, CONC n.v.; isotype, ZT (Horak)), 26b (paratypes, CONC n.v. & M n.v.).
LOS LAGOS—Valdivia, Universidad Austral Chile, Facultad Ciencias Biológicas, jardín del estacionamiento,
Valenzuela et al. (1992) report material from under Nothofagus dombeyi: 28.v.1990 (AH 13910).
Singer seems to have used the unpublished herbarium name “Amanita umbrinella f. exannulata” for some specimens of the present species (or something extremely close to it). The sources of the following description are collection labels, Singer’s notes on his M1773 in his Amanita notebook, examination of the exsiccatum, and
—R. E. Tulloss
Information to support the viewer in reading the content of "technical" tabs
can be found here.
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.