All information is taken from Corner and Bas (1962).
The cap of A. xanthella is 20 - 45 mm wide, shallow concave with a flat margin, pale
yellow, deeper yellow in the center, dry, with a tuberculate-striate margin. The cap is set with small,
mealy, bright yellow, pyramidal warts crowded in the center, and scattered and smaller toward the margin.
The gills are free, crowded, thin, white, with a very pale yellow, entire edge.
The stem is 30 - 60 × 2 - 4 mm, solid, becoming hollow, white, and slightly
fibrillose-floccose. The base is set with small, yellow, mealy flocks as volval remnants.
According to the original description (1962), spores from dried material measure 6.5 -
7.4 (-8.1) × 5.1 - 7.1 µm (from fresh, 7 - 9 µm wide) and are subglobose to broadly ellipsoid and amyloid.
Clamps were not observed at the bases of basidia.
This species was described from Singapore.
The striate margin is unusual in Amanita sect. Validae, but there are
some tropical species (especially small, delicate ones) that have this character. Small taxa in sect. Validae with
friable yellow volvas are listed for purposes of comparison under
A. flavoconia G. F. Atk. var. flavoconia.—R. E. Tulloss
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L (in liquid)
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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).
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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 derived entirely from the protolog of the present taxon.
from protolog: 20 - 45 mm wide, pale yellow, deeper yellow in center, shallowly concave with flat margin, dry; context white, firm: margin tuberculate striate (O.3 - 0.35R); universal veil, as small mealy warts, bright yellow, pyramidal, ca. 1 - 1.5 mm high and wide, crowded over disc, scattered and smaller toward margin.
from protolog: free, crowded, white, with edge entire and very pale yellow, thin, up to 6 mm broad, about 42 primaries; lamellulae attenuate, with 0 - 1 (-3) between each pair of otherwise adjacent lamellae.
from protolog: 30 - 60 × 2 - 4 mm (width measured at apex), white, slightly fibrillose-floccose above and below partial veil; context solid, becoming hollow, white; bulb small, 6 - 12 mm wide; partial veil in lower third of stipe, narrow, pendent, white, with edge set with mealy yellow particles; universal veil as yellow mealy flocculent warts, 0.5 mm or less wide covering much of stipe's bulb.
from protolog: 25 - 80 µm thick, apparently with elements embedded in colorless matrix; filamentous hyphae 2 - 5 µm wide, interwoven, distant, with yellow vacuolar pigment. Underlying layer ("hypoderm"): not sharply delimited; filamentous hyphae more or less radially oriented; inflated cells fusiform. [Note: It is common for the upper part of the pileus context to take a compressed form below the pileipellis and for this part of the context to have an ill-defined lower boundary. Perhaps this is what is being described as a "hypoderm" in this case. Nevertheless, this is not completely clear. The unique nature of other tissues in A. xanthella suggest the need for thorough revision.—ed.]
from protolog: very indistinctly bilateral, subcellular; filamentous hyphae present; inflated cells dominating, ellipsoid to globose, up to 70 × 35 µm. [Note: Another very unusual tissue in this unique species.—ed.]
from protolog: not differentiated from lamella trama, compromising large "sphaerocysts." [Note: Again, an unusual description for an Amanita.—ed.]
from protolog: 25 - 36 × 8 - 12 µm, 4-sterigmate, with sterigmata up to 5 µm long, in hymenium often interspersed with up to 15 µm wide, isodiametric or broadly clavate hyaline inflated cells; clamps not observed. [Note: I have never seen any other Amanita hymenium described as having this form.—ed.]
from protolog: On pileus, wart base: inflated cells globose, up to 70 µm wide, terminal singly, with yellow contents. On pileus, wart apex: inflated cells smaller, sometimes cylindric, yellow, in more or less erect terminal chains. On stipe base: filmentous hyphae 3 - 10 μm wide; inflated cells as "sphaerocysts," up to 60 µm wide, yellow, terminal singly.
from protolog: longitudinally acrophysalidic; filamentous hyphae present; acrophysalides cylindric to clavate, up to 225 × 45 µm; refractive hyphae up to 10 µm wide, twisting, scarcely septate.
lamella edge tissue
from protolog: "partly fertile"; inflated cells rare, globose, 17 - 24 µm wide. [Note: The description of the edge of the lamellae as "partly fertile" is so unusual in Amanita as to merit a word like "extraordinary." The tissue should be revised to provide a deeper understanding of its structure.—ed.]
from protolog: [-/-/-] 6.5 - 7.4 (-8.1) × 5.1 - 7.1 µm, (Q = 1.05 - 1.30), colorless, hyaline, thin-walled, amyloid, subglobose to broadly ellipsoid, sometimes ovoid or obovoid; apiculus rather narrow; contents granular opalescent, vitreous; color in deposit not recorded. In fresh material, spores said to measure 7 - 9 μm.
from protolog: Solitary. Terrestrial in forest.
from protolog: SINGAPORE: Bukit Timah, 27.iii.1943 E. J. H. Corner s.n. (holotype, L in liquid).
from protolog: "The great difference between the results of the measurements of the spores of fresh and of preserved material, may be due to the fact that the mature spores got lost in the preservation liquid.
"In a tentative arrangement of the material, this species was put into section ... [Amanita] on account of its great resemblance to A. mira, although the attenuate short gills caused some doubt. Nevertheless, it was a bit of a surprise later on to find the spores to by amyloid. In this way the number of species in section Validae, characterized by bright colors and a striate margin of the pileus, is increased again after its reduction by the removal of A. rubrovolvata."
In the protolog (Corner & Bas 1962: 275), the authors discuss the rather isolated position of this taxon in section Validae. The species seems even more isolated after the passage of over 60 years.
—R. E. Tulloss
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Corner & Bas
"Yellow Penny Amanita"
1. Amanita xanthella, Singapore.
2. Amanita xanthella, Singapore.
Prof. E. J. H. Corner - (1-2) Singapore, illustration from original description (Corner & Bas, 1962) reproduced by courtesy of Persoonia, Leiden, the Netherlands.
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a single collection inadvertently contains a mixture of taxa.