The data below is based on the original description and original research by RET.
The cap is 105 mm wide and pale gray-brown, darker and depressed in the center. It is flat to more or less convex, smooth, floppy and fragile. The flesh is thin, and the edge is conspicuously grooved for about half of the cap's radius. Usually, there are no volval remnants on the cap.
The nearness of the gills to the stem and their density were not reported. Gills are white, with their edges sometimes dark brown at least in spots (but hard to see with the naked eye). Unevenly distributed and sparse, short gills are of diverse lengths, with the shortest squarely cut off and the longest ending more gradually.
The ringless stem is 83 × 7 - 10 mm and pale golden brown, with darker brown fibrils in a chevron-like pattern, narrowing upward, slender, delicate, and fragile. The stem's flesh was not described. The volva is sack-like, red-brown on the outer surface and gray on the inner surface, broadly spreading, and less than 20 mm high (from the base of the stem to the highest point on the sack).
Odor and taste were not described for this species.
The spores are (9.4-) 9.8 - 12.0 (-13.4) × (8.3-) 9.1 - 11.2 (-12.6) µm, subglobose to broadly ellipsoid (occasionally globose), and inamyloid. Probably lacking clamps at the bases of basidia.
The only known specimen of this species was found in a grassy ride through mixed woodland, with nearby trees including Spruce, Birch, and Hawthorn.—R. E. Tulloss and N. Goldman
(D. A. Reid) Tulloss in Tulloss et al.
Amanitaceae 1(2): 2.
"Limp Ringless Amanita"
≡Amanita umbrinolutea var. flaccida D. A. Reid. 1987. Notes Roy. Bot. Gard. Edinburgh 44: 517.
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 unreleased (pending) pages.
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The following text may makes multiple use of each data field.
The field may contain magenta text representing a type study
The same field may also contain black text, which will represent a revision of the
species by Tulloss. 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 is based on the protolog of A. umbrinolutea var. flaccida and original research of R. E. Tulloss.
RET type study: 105 mm wide, pale gray-brown, darker over depressed disc, smooth, convex to planar to plano-concave in age, flaccid, fragile; context thin; margin conspicuously sulcate (0.5±R); universal veil absent.
RET type study: nearness to stipe and density not reported, white, with edge minutely punctate with dark brown (most conspicuous toward pileus margin, but scarcely visible to naked eye); lamellulae of diverse lengths, with shortest truncate and longest sub(?)attenuate, unevenly distributed, apparently rather sparse.
RET type study: 83 × 7 - 10 mm, pale golden brown, with darker brown fibrils in chevron-like pattern, narrowing upward, gracile, delicate, fragile; context not described; exannulate; universal veil as saccate volva, red-brown on outer surface and gray on inner surface in fresh material, in exsiccatum with pale orangish tan exterior and pallid interior surfaces above base and white with rusty spots and stains near base, broadly spreading, less than 20 mm from base of stipe to highest point on limb.
RET type study: 115 - 135 µm thick, yellow-orange in KOH solution, with surface gelatinized; filamentous, undifferentiated hyphae 1.8 - 7.0 µm wide, densely packed vertically, with subradial arrangement; vascular hyphae 7.0± µm wide, sinuous, infrequent.
RET type study: filamentous, undifferentiated hyphae 2.8 - 12.6 µm wide, branching, plentiful, often in fascicles loosely interwoven around acrophysalides; acrophysalides fusiform to subfusiform to broadly subfusiform to clavate to broadly clavate to broadly subpyriform, up to 87 × 58 µm, thin-walled; vascular hyphae 7.7 - 16.1 µm wide, branching, common, often with encrustations.
RET type study: bilateral, poorly to very poorly rehydrating, with subhymenial base apparently entirely composed of branching uninflated hyphae; filamentous, undifferentiated hyphae 1.3 - 8.4 µm wide, tangled and interwoven, sometimes with constricted septa, with intercalary chains of fusiform cells (poorly reinflated, up to 68 × 24 µm) probably in central stratum; divergent, terminal, inflated cells not observed; vascular hyphae 2.8 - 10.5 µm wide, branching, scattered.
RET type study: somewhat poorly to poorly rehydrating, as tangle of plentifully branching hyphae, with basidia arising from end or side of uninflated hyphal segments or from partially inflated hyphal segments.
RET type study: (28-) 36 - 48 (-53) × 10.8 - 14.4 µm, 4-sterigmate, some with dextrinoid granular contents; clamps rare or absent (basal septa often hard to see).
RET type study: At stipe base, exterior surface: an open weave of criss-crossing fascicles of hyphae; filamentous, undifferentiated hyphae 1.0 - 10.5 µm wide, branching, dominating, often constricted at septa, sometimes having yellowish subrefractive walls, partially gelatinized at surface; inflated cells scattered, terminal, single, dissociable, partially collapsed, ovoid, up to 33 × 26 µm, thin-walled; vascular hyphae 3.5 - 11.2 µm wide, branching, locally densely tangled, locally plentiful, sinuous, not in fascicles. At stipe base, interior: filamentous, undifferentiated hyphae 2.1 - 14.0 µm wide, dominant, branching, plentiful, thin-walled, often in fascicles; inflated cells scattered to locally clustered, thin-walled, clavate to broadly clavate to narrowly ellipsoid to subglobose, up to 46 × 38 µm; vascular hyphae 2.1 - 8.4 µm wide, branching, common, locally plentiful, sinuous, with walls thin to less than 0.5 µm thick. At stipe base, inner surface: like interior, but with proportionately more filamentous, undifferentiated hyphae, with inflated cells partially gelatinized.
RET type study: longitudinally acrophysalidic; filamentous, undifferentiated hyphae 1.4 - 7.7 µm wide, thin-walled, some with yellow refractive granular deposit on inside of walls; acrophysalides up to 164 × 28 µm, thin-walled, sometimes containing yellowish material (as in hyphae) concentrated near basal septum; vascular hyphae 1.4 - 9.1 µm wide.
RET type study: [40/1/1] (9.4-) 9.8 - 12.0 (-13.4) × (8.3-) 9.1 - 11.2 (-12.6) µm, (L = 10.9 µm; W = 9.9 µm; Q = (1.0-) 1.05 - 1.16 (-1.20); Q = 1.10), hyaline, colorless, smooth, thin-walled, inamyloid, subglobose to broadly ellipsoid, occasionally globose, usually adaxially flattened; apiculus sublateral, broad, cylindric to truncate-conic, prominent; contents monoguttulate; color in deposit not recorded.
RET type study: In grassy ride through mixed woodland, with nearby trees including Picea, Betula, and Crataegus.
RET type study: U.K.: ENGLAND—West Sussex, Madehurst, 11.viii.1982 D. A. Reid & Audrey Thomas s.n. (holotype, K).
The presence of dextrinoid granules in the basidia of a species of Amanita section Vaginatae is very unusual in RET's experience. I believe this type study may be the first report of such an occurrence. In the genus as a whole, the character is known in only three taxa—the other two assignable to Amanita section Lepidella and, hence, distantly related (Bas, 1969; Tulloss and Franco-Molano, 2008): A. mutabilis and A. savannae.
A comparison of spore-size and shape in A. umbrinolutea and the present species are presented in the following figure:
The spores of the two species are very much the same shape; however, the spores of A. umbrinolutea can be significantly larger than those of the present species. Other striking differences between the present taxon and A. umbrinolutea include the flaccid, non-zonate pileus which lacks a reddish tint and has a diameter greater than the stipe length; and a universal veil with an unusually pigmented ("red-brown") exterior surface.
—R. E. Tulloss
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