This taxon was collected by Joseph Laferrière during ecological and ethnomycological studies in the state of Chihuahua, Mexico. RET has seen a draft description (Ms.) of Laferriere and two specimens from a large collection that he distributed over several herbaria. The following is based in part on the Ms.
The cap is 100 - 180 mm wide, white to cream, and becomes pale tan with age [per photos], planoconvex to planar at maturity, with low broad umbo at maturity or in age, subviscid when moist; context white, ??, thinning ?? to margin, not changing when cut or bruised; margin short striate (??R), nonappendiculate; universal veil absent.
The gills are free, crowded, pale yellow in mass and in side view. The short gills are truncate to subtruncate or rounded truncate, of diverse lengths, plentiful, and unevenly distributed.
The hollow stem of this mushroom is 120 - 180 × 15± mm, white or whitish, narrows upward, and flares at the very top. The ring is placed high on the stem and is thin, membranous, persistent, pale yellow at first, and becomes darker and slightly brownish yellow with age and then collapses on the stem. The sack-like volva is lobed, white, and has a limb reaching up to 30 - 75 mm from the bottom of the sack.
This mushroom's odor and taste are not recorded.
The spores measure (7.5-) 9.2 - 12.8 (-15.0) × (5.8-) 6.5 - 8.2 (-9.0) μm and are predominantly broadly ellipsoid to ellipsoid (occasionally elongate, infrequently subglobose) and inamyloid. Clamps are found at bases of basidia.
This species is known from the Sierra Madre Occidental in the state of Chihuahua, Mexico, where it was collected in pine-oak (Pinus-Quercus) forest.
In the region where it was collected it is a comestible species enjoyed by the local people.
Its macroscopic characteristics place this mushroom in Amanita [sect. Caesareae] stirps Caesarea along with such species as A. caesarea of Europe and the Mexican species A. basii.—R. E. Tulloss
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100 - 180 mm wide, white to cream, becoming pale tan with age [per collector's photos], planoconvex to planar at maturity, with low broad umbo at maturity or in age, subviscid when moist; context white, ??, thinning ?? to margin, not changing when cut or bruised; margin short striate (??R), nonappendiculate; universal veil absent.
free, crowded, pale yellow in mass and in side view, becoming ?? in exsiccata, with edges ?? and becoming ?? at maturity, ?? mm broad; lamellulae truncate to subtruncate or rounded truncate, of diverse lengths, plentiful, unevenly distributed.
120 - 180 × 15± mm, white or whitish, narrowing upward, flaring at apex; context ??, hollow, with central cylinder ?? mm wide; partial veil superior, thin, membranous, persistent, pale yellow, becoming darker and slightly brownish yellow with age, collapsing on stipe in age; universal veil saccate, lobed, white, with limb reaching up to 30 - 75 mm from base of stipe.
90 - 100 µm thick (in mature specimen), gelatinized at surface, with 25± µm thick colorless suprapellis of gelatinized to partially gelatinized hyphae, with 65 - 75 µm thick brownish yellow ungelatinized subpellis; filamentous, undifferentiated hyphae 1.5 - 4.5 (-6.4?) µm wide, branching, densely packed vertically and horizontally, dominantly subradially arranged; vascular hyphae not observed (with refractive hyphae of hyphomycete present in RET isotype).
filamentous, undifferentiated hyphae 2.5 - 12.7 µm wide, branching, plentiful, singly and in narrow fascicles, interwoven forming open lattice structure; acrophysalides plentiful, thin-walled, narrowly clavate to clavate to broadly clavate, up to 183 × 51 µm; vascular hyphae 7.6 - 17.8 µm wide, rare.
poorly rehydrating in available material; bilateral; vascular hyphae 3.9 - 10.6 µm wide, branching, frequency unclear.
poorly rehydrating in available material; pseudoparenchymatous, with inflated cells in 4 to 5 irregular layers below bases of longest basidia, with larger cells up to 20 × 15.0 µm, with basidia arising from inflated cells.
35 - 44 (-52) × 7.8 - 10.8 (-11.5) µm, thin-walled, 4- and occasionally 1- or 2-sterigmate, with sterigmata to 9.0 × 2.5 µm long; clamps occasional??, unevenly distributed, sometimes prominent.
On pileus: absent. At stipe base, exterior surface layer: filamentous undifferentiated hyphae branching, partly gelatinized to gelatinized, collapsed, in fascicles and singly, interwoven leaving gaps through which interior tissue visible, lacking dominant orientation. At stipe base, interior layer: filamentous, undifferentiated hyphae 2.3 - 8.9 (-12.7??) µm wide, branching, plentiful, dominantly single, occasionally in narrow fascicles, loosely interwoven in open lattice structure; inflated cells thin-walled, plentiful to locally dominant, terminal singly, clavate to broadly clavate to ovoid (to 108 × 51 µm), ellipsoid to subglobose (to 79 × 74 µm); vascular hyphae not observed. At stipe base, inner surface: often like interior although extensively gelatinized and collapsed, occasionally with superficial broad fascicles of gelatinized filamentous, undifferentiated hyphae.
longitudinally acrophysalidic; filamentous, undifferentiated hyphae 2.5-12.5 µm wide, branching, dominant near surfaces, plentiful in interior; acrophysalides with walls thin or slightly thickened, ranging from rather broad (up to 184 × 51 µm) to narrow (up to 174 × 29 µm), dominant away from surfaces; vascular hyphae not observed; clamps rare.
filamentous, undifferentiated hyphae 1.3 - 11.4 µm wide, branching, singly and in fascicles, interwoven, but with many fascicles subradially arranged, dominating; inflated cells scattered in interior, thin-walled, terminal singly, clavate, up to 41 × 22 µm; vascular hyphae 3.8 - 16.5 µm wide, coiling, sinuous, common, unevenly distributed; clamps moderately common, prominent.
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.