=Amanita malheurensis Trueblood, O. K. Mill. & Dav. T. Jenkins
1. Amanita prairiicola, high altitude desert, SE Arizona, U.S.A.
This description is based on an unpublished study of the Amanita
prairiicola by the author of this page.
The cap of A. prairiicola is 19 - 110 mm wide, convex at first
then plano-convex, white at first between volval patches, then more or less tinged with yellow or faintly brownish
cream throughout, appedendiculate, with a nonstriate margin, at first incurved, then decurved with age. The
volva is present as flat, thin warts or small patches, whitish to pale off-white to tan to brownish, and roughly
The gills are free to narrowly adnate, subdistant to crowded, and pale pinkish
cream to slightly yellowish cream in mass. The short
gills are truncate to rounded truncate to subattenuate to
attenuate, unevenly distributed, of diverse lengths, and plentiful.
The stem is 40 - 80 × 4 - 25 mm, cylindric or subcylindric or slightly narrowing
upward or downward, and white or whitish. There is a
persistent, similarly colored annulus with a thickened
edge. The volva is usually absent or very scant as scattered small concolorous to
faintly sordid polygonal warts below the annulus. The
stipe base is not bulbous and can be slightly "rooting."
The spores measure (8.0-) 10.0 - 14.0 (-19.2) × (5.2-) 6.4 - 10.0 (-12.2) µm and
are amyloid and broadly ellipsoid to ellipsoid to elongate. Clamps are common and prominent at bases of
This species occurs naturally in the central USA with a range from the state
of Arizona to eastern Oregon and eastward to Kansas, from which it was first described. One specimen has been found
in a planted area in Argentina. It may have been imported with soil.
Amanita prairiicola is a species of tall grass prairie and high elevation
desert. It is frequently found with no nearby woody plant
symbiont. It has been found in desert with no living plant in its vicinity.
≡Amanita praticola Sacc. nom. inval.1899. Syll. Fung. 14: 63. [Avowed replacement for validly published name. ICBN §52.1]
=Amanita malheurensis Trueblood, O. K. Mill. and Dav. T. Jenkins in O. K. Mill., Trueblood and Dav. T. Jenkins. 1990. Mycologia 82: 126, figs. 8-10, 14-15.
The editors of this site owe a great debt to Dr. Cornelis Bas
whose famous cigar box files of Amanita nomenclatural information
gathered over three or more decades were made available to RET for computerization
and make up the lion's share of the nomenclatural information presented on this site.
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.
Tulloss. 2000a. Boll. Gruppo Micol. G. Bresadola 43(2): 18, fig. 10.
This description is based on the research of Tulloss.
19 - 110 mm wide, white at first between universal veil patches, then more or less tinged with yellow or faintly brownish cream throughout, unchanging when cut or bruised, at first appearing felted (10× lens) between patches of universal veil, then shiny in same areas after in situ drying, convex with incurved margin at first, plano-convex with decurved margin at maturity, sometimes convex in age; context white, unchanging when cut or bruised, 2.5 - 9.5 mm thick, thinning evenly to margin; margin nonstriate, appendiculate, with 1 mm thick continuation of pileus originally connected rather firmly to stipe in buttons, in mature material extending up to 3 mm beyond end of lamellae; universal veil as flat thin warts or small patches, whitish to pale off-white to pale buff to light dull ochraceous to tan to brownish, sometimes becoming browner with age, roughly polygonal, subpruinose in buttons, on older material glistening when fresh as if wet, eventually becoming radially striatulate (suggesting tiny cedar roof shingles) on drying in situ, not detersile, but becoming almost entirely reduced by gelatinization.
free to narrowly adnate, without decurrent line on stipe apex, sometimes with faint decurrent tooth, subdistant to crowded, pale pinkish cream to slightly yellowish cream in mass, white to off-white to creamy white to faintly yellowish cream in side view, sometimes with pinkish-brownish or cinereous tint in half nearest edge at maturity, unchanging when cut or bruised, 3 - 8 mm broad, occasionally anastomosing scattered in spots; lamellulae truncate to rounded truncate to subattenuate to attenuate, unevenly distributed, of diverse lengths, plentiful, occasionally seen connecting to stipe instead of to pileus margin.
40 - 80 × 4 - 25 mm, white or whitish, becoming yellowish to pale brown to reddish brown where handled or in age, cylindric or subcylindric or slightly narrowing either upward or downward, not flaring at apex, finely fibrillose to finely pulverulent (not satiny) above partial veil, finely fibrillose to satiny and finely longitudinally striatulate below, with obscure rings of very thin recurved scales below annulus, with such scales becoming brownish (browner than ground color) and collapsing on stipe, with up to 35% of length inserted in substrate, with rounded point at base; bulb lacking or as very limited swelling in lower stipe; context white to off-white, not changing when cut or bruised, solid, sometimes very dense and hard to cut (almost woody in one specimen) even with new razor (and then exuding water when cut); partial veil superior, narrow, white, becoming very pale brownish to slightly sordid with in situ drying, thin, membranous, smooth or faintly striate above, smooth below, persistent, with margin decorated below with rather closely spaced small subrectangular blocks of universal veil (i.e., with margin thickened as illustrated for A. vittadinii), sometimes inconspicuous on exsiccata; universal veil absent or very scant as scattered small concolorous to faintly sordid polygonal warts below partial veil.
Odor lacking or earthlike or medicinal or “antiseptic” or faintly “chemical” until sectioned, then unpleasant, fetid and penetrating, like turpentine or dog urine or dog feces according to some informants. Taste not distinctive.
95% ethanol - negative on surfaces and context of both pileus and stipe, and on lamellae. FeSO4 - greenish on pileus surface (universal veil?), light orange on pileus context. NH4OH - negative on surfaces and context of both pileus and stipe, and on lamellae. Spot test for laccase (syringaldazine) - negative throughout basidiome. Spot test for tyrosinase (paracresol) - strongly positive only on surface of pileus (including universal veil); weakly positive in upper stipe, very base of stipe, and cap context just above lamellae. Test vouchers: Trueblood 2644, 6441; Tulloss 8-24-96-A, 8-18-97-C.
lacking, with acrophysalides noted at or near surface even in immature basidiome (in scalp section) in regions lacking universal veil.
becoming more dense (having greater proportion of hyphae and smaller acrophysalides) toward pileus surface and toward attachment of lamellae, with dense region at surface sometimes more yellowish or more yellow-orange than adjacent tissues, gelatinized just at surface where exposed; filamentous, undifferentiated hyphae 2.2 - 9.4 µm wide, branching, at times in fascicles, plentiful to dominating, sometimes with yellowish subrefractive walls, with occasional slightly inflated intercalary elements (up to 13.5 µm wide), moderately densely interwoven in open lattice except near surface and near lamellae (see above); acrophysalides unevenly distributed, common locally, subglobose to ovoid to ellipsoid to narrowly ellipsoid to broadly clavate to narrowly clavate to subfusiform, up to 68 × 39 µm, apparently terminal, with walls thin or slightly thickened; vascular hyphae concentrated near pileus surface and crossing into universal veil, otherwise not observed, 2.5 - 15.5 µm wide, branching, subsinuous to sinuous, occasionally coiling or tangled, irregularly distributed, but locally common, can be obliterated except for scattered fragments when volva and surface of pileipellis sufficiently gelatinized.
rehydrating poorly in type material; bilateral; central stratum prominent, including some intercalary inflated hyphal segments, with wcs = 70 - 100 µm (good rehydration) ranging to 30 - 45 µm (poor rehydration); subhymenial base dominated by intercalary chains of elongate partially inflated cells (up to 65 × 10.5 µm and almost all less than 15.0 µm wide) and scattered smaller broader cells (up to 57 × 22 µm or larger); angle of divergence shallow, with elements forming smooth curve and eventually becoming perpendicular to central stratum in or just below subhymenium; filamentous, undifferenti~ated hyphae 0.9 - 8.6 µm wide, branching, with plentiful intercalary inflated segments; terminal divergent, inflated cells not observed; vascular hyphae not observed; clamps rather prominent.
30 - 35 µm wide; wst-near = (?30-) 50 - 70 (-95) µm; wst-far = (?35-) 70 - 85 (-110) µm; variable, from nearly cellular [and then 3 - 6 (-7) cells deep, with individual cells up to 26 × 14.5 µm] to a mixture of small inflated cells and relatively long (20± µm) uninflated or partially inflated hyphal segments (mostly less than 9.0 µm wide), with one to two cells between bases of shortest basidiole in given region and nearby longest basidium/-ole, with basidia arising from cells of all types, but often from uninflated hyphal segments; clamps relatively plentiful.
(29-) 36 - 57 (-65) × 8.3 - 15.2 µm, with walls thin to slightly thickened (up to 0.5 µm thick), dominantly 4-, but also 2-, and less frequently 3- and 1-sterigmate; sterigmata up to 12.5 × 3.2 µm, mostly shorter, sometimes with slightly thickened walls; clamps common, prominent.
On pileus: with periclinal arrangement, very thin and largely gelatinized in most material, at least with surface gelatinized, with elements subradially arranged or disordered (in type of A. prairiicola) when viewed from above; filamentous, undifferentiated hyphae 1.5 - 7.5 µm wide, branching, plentiful to dominant in basal layer about two hyphal diameters thick, often in fascicles; inflated cells dominating above basal layer, narrowly ellipsoid to clavate to fusiform to narrowly fusiform, terminal or in chains, with terminal cells at least sometimes mucronate, up to 215 × 41 µm, with most less than 150 µm long, thin-walled; vascular hyphae 2.7 - 15.5 (-18.0) µm wide, branching, subsinuous to sinuous, irregularly distributed, locally common, not infrequently passing into pileus context; clamps scattered. On lower stipe: present only as scattered gelatinized shreds, irregularly dispersed over stipe, almost completely collapsed; filamentous, undifferentiated hyphae in fascicles or singly, branching, dominating; inflated cells distinguishable only here and there, in chains, subcylindric to narrowly subfusiform, up to 81 × 18.4 µm.
longitudinally acrophysalidic, with addition of longitudinally oriented intercalary cells in chains; filamentous, undifferentiated hyphae 1.5 - 9.2 µm wide, dominating, branching, often in fascicles, sometimes with slightly thickened walls; acrophysalides ellipsoid to narrowly ellipsoid to broadly clavate to clavate, terminal, with walls usually slightly thickened (up to 0.9 µm thick), up to 223 × 39 µm (but mostly less than 130 µm long), less common than chains of inflated intercalary cells, very infrequent near stipe surface, otherwise moderately common locally; inflated cells in chains, subcylindric to cylindric to occasionally slightly expanded or narrowly fusiform, then up to 22 µm wide, often relatively short, septa unconstricted or slightly constricted, with walls thin or up to 1.0 µm thick, locally frequent; vascular hyphae not observed in types (of both A. prairiicola and A. malheurensis), but at least locally common in other material; clamps common, prominent.
filamentous, undifferentiated hyphae 1.2 - 9.5 µm wide, branching, subradially arranged, often in fascicles, dominating, densely packed; inflated cells infrequent to uncommon, thin-walled, pyriform (e.g., 24 × 20 µm); vascular hyphae not observed; clamps present.
from type study of Jenkins (1978a): [-/-/1]
11.7 - 14.1 × 8.6 - 10.9 μm, (Q = 1.24 - 1.45; Q' = 1.33),
hyaline, thin-walled, amyloid, broadly ellipsoid to ellipsoid, often adaxially flattened; apiculus sublateral, cylindric; contents guttulate;
color in deposit not recorded.
[700/34/11] (8.0-) 10.0 - 14.0 (-19.2) × (5.2-) 6.4 - 10.0 (-12.2) µm, (L = (10.4-) 11.0 - 13.3 (-13.7) µm; L’ = 12.0 µm; W = (6.5-) 6.6 - 9.6 (-9.7) µm; W’ = 8.0 µm; Q = (1.09-) 1.26 - 1.82 (-2.31); Q = (1.30-) 1.33 - 1.75 (-1.85); Q’ = 1.51), hyaline, colorless, smooth, with wall dominantly thin to dominantly slightly thickened (usually less than 0.5 µm thick, occasionally up to 0.8 µm thick), amyloid, with surface infrequently aereolate in older collections (in such cases, with strongly amyloid plaques distinguishable against paler ground), broadly ellipsoid to ellipsoid to elongate, occasionally cylindric, occasionally slightly, but often not at all, adaxially flattened, sometimes swollen at one end; apiculus sublateral, cylindric or truncate-conic, proportionately small; contents granular to monoguttulate (with or without additional small granules); white in deposit.
Solitary to subgregarious to gregarious. Argentina: In meadows far from any kind of trees. Arizona, U.S.A.: At ? m elev. In monsoon season, in hard dry sandy soil by narrow dry wash (other washes nearby still damp from runoff of recent rains in nearby mountains), among Upper Sonoran life zone vegetation apparently without ectomycorrhizal woody plants, dominated by Prosopsis velutina Woot. Colorado, U.S.A.: At 1625± m elev. In grass between sidewalk and street, with nearby landscaped lawn including Picea pungens Engelm., with soil dry although just following three weeks of record-setting, almost daily rainfall. Kansas, U.S.A.: In "high, open prairie in short grass." Oregon: With Bromus tectorus [auth.?] and decaying sticks (possibly of Artemisia tridentata [auth.?]) in sandy soil at edge of graded desert road or in cheat grass desert range area without trees and with Sarcobatus vermiculatus [auth.?] only shrub in area. Wyoming, U.S.A.: At 1450 m elev. In open grassland.
Dr. Richard Kay (Lawrence, Kansas) has informed me that Elam Bartholomew’s diary (preserved in the Kansas State Historical Society, Topeka) indicates that, shortly before the 1895 Rockport collection was made, there were torrential rains and that Bartholomew (loc. cit.) records that there was a very unusual variety of fungi to be found as a result. As noted, there were extraordinary rains in Colorado in 1997 before the Denver collection was made; and the Arizona collection was made during the annual monsoon season in southeastern Arizona.
For further study: Center for Historical Research, 120 W. 10th Street, Topeka, KS 66612. 913-296-4776. Microfilm rolls MS-1070 (1882-1896), MS-1071 (1897-1908), MS-1072 (1908-1919), MS-1073 (1919-1930). Fort Hays State University, Hays, KS (HAYS) is locality of herbarium left by Bartholomew.
Bas (1969): U. S. A.: KANSAS— Rooks Co. - Stockton, 20.i.1927 E. Bartholomew s.n. (MICH); unkn. loc., 17.ix.1896 E. Bartholomew 2272 (holotype, NYS).
from type study of Jenkins (1978a):
U. S. A.: KANSAS— Rooks Co. - unkn. loc., 17.ix.1896 E. Bartholomew 2272 (holotype, NYS).
RET: ARGENTINA: TUCUMÁN—Valle de San Javier, est. Paz-Posse, 30.xii.1951 R. Singer & Heilberger [Singer T1671] (BAFC 30.609).
U.S.A.: ARIZONA—Cochise Co. - ca. Ft. Bowie Nat. Hist. Site [32°09’22” N/ 109°27’10” W], 24.viii.1996 M. A., S. E. & R. E. Tulloss 8-24-96-A (RET 248-4).
COLORADO—Denver Co. - Denver, ca. Denver Bot. Gard, ca. 11th & Vine St. [34°43’51” N/ 104°97’38” W], 18.viii.1997 Gary Picket s.n. [Tulloss 8-18-97-C] (DBG ??; RET 266-1).
KANSAS—Phillips Co. - unkn. loc., 27.viii.1901 Elam Bartholomew s.n. (FH). Rooks Co. - Rockport, near S border of Phillips Co., 31.vii.1895 E. Bartholomew 1865 (FH as "Armillaria constricta Fr."); Stockton, 20.vi.1927 E. Bartholomew 9824 (FH; MICH); unkn. loc., 17.ix.1896 E. Bartholomew 2272 (holotype, NYS; isotype, BPI; isotype, FH; isotype, NY).
OREGON—Malheur Co. - rd. to Rock Spring & Lone Willow Spring, 22.vi.1978 E. Trueblood 6441 (paratypes of A. malheurensis, L & MICH); ca. Warm Springs Reservoir, Juntura Riverside Rd., 26.v.1991 Ester Lively s.n. (RET 003-2); btwn. Willow Springs & Negro Rock, 9.vi.1967 Ted & E. Trueblood 2644 [O. K. Miller 24122 (erroneously as "24127" in protolog)] (holotype of A. malheurensis, VPI, n.v.; isotype, L; isotype, MICH 429).
WYOMING—Platte Co. - Glendo, 4.vi.1959 R. E. Pfadt s.n. (RMS 47079; MICH).
The four highest values of Q observed were from the specimens of Bartholomew 9824. While the packet of Bartholomew 9824 in FH is marked “Plants rather immature,” spore lengths have an approximately normal distribution in the specimens of the collection with only one showing a slight tendency toward longer than average spores. These specimens have spores of the size and with roughly the range of Q found in more recent collections. The remainder of the material (including holotype and isotypes) has larger spores with Q not exceeding 1.48. In particular, none of the specimens of the type has Q larger than 1.41; and, collectively this group of specimens has L’ = 12.6 µm. The remaining six Bartholomew-collected specimens reviewed produce L’ = 11.8 µm~—more in line with the subsequent collections.
Apparently the type material of A. prairiicola was collected in an early stage of sporulation. While there are relatively plentiful spores on the lamellae, there are regions at and beyond the midpoint of the lamellae where there are few or no mature basidia visible in sections. A detailed review of the basidia in the NY isotype revealed that bisterigmate basidia generally dominate sections in which basidia with sterigmata are present and that, when 4-sterigmate basidia are found, they tend to be clustered. There were also basidia with single, abnormally large sterigmata as well as 3-sterigmate basidia. Moreover, the distribution of spore length in the type material is not normal. In fact, the length distribution is shifted toward greater length.
One of the most difficult sets of tissues to understand in this species is that including the universal veil and the pileus context. When examining the tissue of the pileus context near its surface with the universal veil in cross section, it is very easy to believe that one is viewing a very thick pileipellis with gelatinization limited to the universal veil and the very surface of the pileus. Viewing a scalp of the pileus will remove this impression; it is clear that, from this vantage, one is viewing small and scattered islands of gelatinized universal veil remnants and, between these, the gelatinized surface of exposed pileus context~—recognizable due to the interwoven, disordered hyphae with occasional gaps and occasional, small inflated cells.
Amanita malheurensis is contaxic with the present species. With the exception of the spore width in some of the oldest collections of A. prairiicola, the spores and the rest of the microscopic anatomies of the original and subsequent material assigned to the two names is very nearly identical.
The mention of a thick pileipellis in the protolog of A. malheurensis appears to have been a misinterpretation of the tissues. Likewise, the description of “cystidioles” in the hymenium may have been based on the presence of collapsed basidia (not unusual in Amanita); no "cystidioles" were found after examination of numerous sections from several basidiomes—in fact no known species of Amanita has cystidia of any kind. Miller repeatedly reported cystidia from amanitas in the descriptions of which he participated; the reason is unclear.
If the projecting sterile margin of the fresh pileus is grasped with tweezers and pulled upward, a layer of superficial pileus tissue can be torn away. Perhaps, this is what gave the impression of a separable pileipellis that is reported in the protolog of A. malheurensis.
The only color information that has been located with a Bartholomew collection of this species is a note found in the box with duplicate material from Bartholomew 9824 (MICH): "white in all its parts."
C. Bas (pers. corresp.) notes that the Singer collection from Tucumán, Argentina cited in his monograph (Bas, 1969: 355-356) had spores which fit within the range now established for A. prairiicola. In his letter to me, Dr. Bas further notes, "There is more reason now to assume that A. prairiicola occurs also in Argentina." After establishing a base concept by examining 30 North American specimens, I reviewed the Argentine collection in question and found that it was not distinguishable microscopically from the North American material. The presence of the species in Argentina is still supported only by the existence of this single collection. When examined (April, 1998), the specimens of this collection had begun to suffer significantly from attack by mold. Whether or not the species is endemic in Argentina is an open issue.
The name Amanita malheurensis was first proposed in manuscript by Alexander H. Smith based on Trueblood 2644.
The present species was briefly called Amanita species AZ27 in my draft keys and species lists.
—R. E. Tulloss
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"American Prairie Lepidella"
1. Amanita prairiicola, high altitude desert, SE Arizona, U.S.A.
RET - (1) high altitude desert, SE Arizona, U.S.A.
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.