The following is derived from the original description of the present species and the description of Tulloss et al. (2001).
The cap of A. orsonii is 20 - 110 mm wide, fleshy to fragile, globose to ovoid to convex when young, becoming broadly convex to plano-convex to plane with age, sometimes with a low, broad umbo, viscid to slightly viscid when wet, with a regular, decurved, nonstriate margin at first, becoming faintly striate with age. The cap is orange-red to grayish red to reddish brown to grayish brown, darker in the disc or having a light brown tinge in the disc, with color fading toward margin. The flesh is thin, white, staining reddish with age or injury, and soft. The volva is present as floccose, flat, polygonal scales and warts; it is white at first, grayish with maturity, and sometimes more plentiful near the margin than over the disc.
The gills are free to narrowly adnexed, close to crowded, white to yellowish white to grayish, staining red to grayish red in age or when bruised, thin, and fleshy to brittle. The short gills are sometimes rounded truncate, of diverse lengths, and unevenly distributed.
The stem is 35 - 150 × 8 - 30 mm, pallid with pink to red blotches to reddish white to grayish red to grayish brown, narrowing upward, pruinose at the apex, smooth to fibrillose, solid, becoming hollow with age, with white flesh. The volva is inconspicuous, friable, ephemeral or leaving few white to grayish white to grayish red to reddish brown patches adhering loosely to the bulb or in soil around the bulb.
Neither the odor nor the taste is distinctive in this species.
The spores measure (6.5-) 7.0 - 9.2 (-10.5) × (5.0-) 5.5 - 7.0 (-8.0) µm and are amyloid and broadly ellipsoid to ellipsoid. Clamps are not observed at bases of basidia.
Amanita orsonii was originally described from the state of Himachal Pradesh in northern India. Its range is now known to extend from the Northwest Frontier Province of Pakistan to Japan (where it has been known as "A. rubescens").
It occurs with oaks and with conifers. The most recent detailed description is provided by Tulloss et al. (2001).
Tulloss et al. 2001. Mycotaxon 77: 484, figs. 16-17.
The following text may make multiple use of each data field.
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
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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 based on (Tulloss et al. 2001) and additional original research of R. E. Tulloss.
Tulloss et al. (2001): 20 - 110 mm wide, color prior to bruising not recorded, orange-red (close to 7A6) to grayish red to reddish brown (8C4, 8E4) to grayish brown (6E3), color darker in disc or having light brown tinge (6D4) in disc, color fading slowly toward margin and there orangish cream in youngest material for which notes exist, brown to fuligineous in exsiccata, fleshy to fragile, globose to ovoid to convex when young, becoming broadly convex to planoconvex to plane with age, sometimes with low broad umbo, viscid to slightly viscid when wet; context thin (confirmed in exsiccata even near stipe), white, staining reddish with age or on injury, with color appearing slowly after cutting or bruising, soft; margin regular, decurved, nonstriate at first, becoming faintly striate with aging, sometimes rimose in mature specimens, with slight sterile rim extending beyond lamellae in one specimen; universal veil as floccose, flat, polygonal scales and warts, white at first, grayish brown at maturity, at least sometimes more plentiful near pileus margin than over disc.
Tulloss et al. (2001): free to narrowly adnexed, close to crowded, white to yellowish white to grayish, staining red to grayish red in age or when bruised as in other parts of the basidiocarp, up to 10 mm broad, thin, fleshy to brittle, edges entire; lamellulae sometimes rounded truncate (shortest), of diverse lengths, unevenly distributed.
Tulloss et al. (2001): 35 - 150 × 8 - 30 mm, pallid with pink to red blotches to reddish white to grayish red to grayish brown, narrowing upward, pruinose at apex, smooth to fibrillose and longitudinally striatulate below partial veil, fibrils becoming reddish brown and appressed; context white, staining reddish to grayish red on injury, particularly in the base, solid when young, becoming hollow with age; bulb up to 15+ mm wide; partial veil superior to submedian, probably slipping down stipe somewhat with age, membranous, thin to moderately thick, white to off-white to reddish white to reddish gray to grayish red, proportionately short, skirt-like, eventually collapsing on stipe, sometimes splitting radially; universal veil inconspicuous, friable, ephemeral or leaving few white to grayish white to grayish red to reddish brown patches adhering loosely to bulb or in soil around bulb.
Tulloss et al. (2001): Odor and taste not distinctive.
Tulloss et al. (2001): Aniline water - reddish brown on pileus context. Conc. HNO3 - yellow to light yellow on pileus context. 2% aqueous phenol - reddish brown on pileus context. All three reagents - negative on pileipellis.
Tulloss et al. (2001): 85± µm thick, gelatinizing only at surface (gelatinized layer is barely more than one hyphal diameter in thickness and colorless), predominantly ungelatinized, yellow-brown to brownish yellow or brownish orange, apparently somewhat collapsed/compressed in some material of isotype; filamentous, undifferentiated hyphae 1.3 - 8.9 µm wide, branching, singly and in fascicles, somewhat loosely interwoven, over disc without dominant orientation and with gaps in layers making layering obvious from above, dominantly subradially arranged near margin, but there also with criss-crossing fascicles; vascular hyphae 4.8 - 15.1 µm wide, infrequently branching, sinuous, with occasional loose or rather tight coils, unevenly distributed, scattered to locally plentiful and in tangles.
Tulloss et al. (2001): partially collapsed and damaged in isotype; filamentous, undifferentiated hyphae 3.8 - 10.8 µm wide, branching, plentiful, singly or in narrow fascicles, interwoven in open lattice structure, sometimes with subrefractive yellowish walls; acrophysalides plentiful, pyriform to broadly clavate (e.g., 69 × 34 µm in isotype), thin-walled; vascular hyphae not observed in isotype, but possibly penetrating adjacent trama somewhat from pileipellis.
Tulloss et al. (2001): bilateral, badly damaged collapsed and even partially gelatinized in isotype; central stratum distinct, apparently dominantly comprising filamentous, undifferentiated hyphae, with some inflated intercalary subfusifrom segments up to 15.5 µm wide; subhymenial base containing inflated cells [often intercalary, ovoid to ellipsoid to broadly clavate to narrowly clavate to subfusiform, up to 61 × 22 (-30?) µm]; filamentous, undifferentiated hyphae 1.5 - 6.8 µm wide, branching; divergent, terminal inflated cells not definable due to state of tissue in isotype, similar in form to intercalary cells of subhymenial base if present; vascular hyphae not observed.
Tulloss et al. (2001): badly damaged, collapsed, and even partially gelatinized in isotype; pseudoparenchymatous, with small globose to subglobose to ellipsoid inflated cells (up to 16.0 × 13.8 µm) in 3 to 5 irregular ranks below base of longest basidia, with basidia arising from inflated cells.
Tulloss et al. (2001): 25 - 44 × 6.0 - 14.0 µm, 4- and infrequently 1-sterigmate, thin-walled, with sterigmata up to 4.0 × 1.5 µm; clamps not observed.
Tulloss et al. (2001): On pileus: elements sometimes showing some vertical orientation, often disordered; filamentous, undifferentiated hyphae 3.6 - 5.1 µm wide, branching, plentiful; inflated cells dominating, thin-walled, colorless or faintly yellowish, yellow-orange to brownish orange in mass, globose to pyriform to ellipsoid to clavate, up to 85 × 55 µm, at least partially collapsed; vascular hyphae not observed, but tissues badly collapsed in all specimens reviewed. On stipe base: elements disordered; filamentous, undifferentiated hyphae 1.9 - 6.4 µm wide, branching, singly and in fascicles, common, more frequent than on pileus; inflated cells plentiful, similar in shape to those on pileus, collapsed and partially gelatinized, pale sordid orange-yellow to orange-brown, up to 67 × 53 µm, singly and in chains of up to 3 cells; vascular hyphae not observed, but tissues badly collapsed in all specimens reviewed.
Tulloss et al. (2001): longitudinally acrophysalidic; filamentous, undifferentiated hyphae 1.5 - 10.3 µm wide, branching, plentiful, dominating near stipe surface, with occasional intercalary partially inflated segments up to 17.8 µm wide; acrophysalides plentiful to dominant except near stipe surface, up to 248 × 55 µm, shorter and proportionately broader near surfaces, with walls thin or slightly thickened (less than 0.5 µm thick); vascular hyphae (4.1-) 6.2 - 17.8 (-20) µm wide, occasionally branching, sinuous, unevenly distributed, scattered to locally common, at times loosely to rather tightly coiling, sordid yellow.
Tulloss et al. (2001): gelatinized on upper surface in isotype; filamentous, undifferentiated hyphae 1.5 - 6.5 µm wide, branching, singly and in fascicles, interwoven in moderately dense lattice, but dominantly (or very nearly dominantly) subradially oriented; inflated cells not identifiable with certainty (except for bits of volva or lamella marginal tissue) in isotype; vascular hyphae 3.6 - 9.1 µm wide, sinuous, infrequent, unevenly distributed, pale sordid yellow-orange.
Tulloss et al. (2001): [153/7/5] (6.5-) 7.0 - 9.2 (-10.5) × (5.0-) 5.5 - 7.0 (-8.0) µm, (L = 7.7 - 8.3 (-8.8) µm; L’ = 8.2 µm; W = 5.9 - 6.3 (-6.7) µm; W’ = 6.2 µm; Q = (1.13-) 1.16 - 1.50 (-1.58); Q = 1.23 - 1.34 (-1.39); Q’ = 1.31), hyaline, colorless, thin-walled, smooth, amyloid, broadly ellipsoid to ellipsoid, infrequently subglobose, often adaxially flattened, often expanded at one end; apiculus sublateral, small, cylindric; contents monoguttulate to multiguttulate to granular; white in deposit.
Composite from all material revised by RET: [258/12/9] (5.8-) 6.8 - 9.2 (-10.5) × (4.8-) 5.5 - 7.0 (-8.0) μm, (L = 7.4 - 8.3 (-8.8) µm; L’ = 8.0 µm; W = 5.9 - 6.3 (-6.7) µm; W’ = 6.2 µm; Q = (1.07-) 1.15 - 1.47 (-1.58); Q = 1.23 - 1.34 (-1.39); Q’ = 1.30).
protolog: Solitary to scattered to
gregarious. At 2300 - 2400 m elev. With
Tulloss et al. (2001): Solitary to
scattered to gregarious. Himachal Pradesh, India:
At 2300 - 2700 m elev. Under Cedrus deodara
(in mixed woods or as solitary tree ) or under
Quercus incana or under Q. incana and
Pinus wallichiana. Uttarakhand, India:
Under Cedrus or near Q. lanata Sm.
(=Q. leucotrichophora A. Camus) and
Rhododendron arboreum. Pakistan:
Associated with Cedrus deodara.
RET: Uttarakhand, India: At 2550 m elev.
Gregarious.nbsp; In mixed conifer-broadeaved
forest with Quercus floribunda and Q.
semicarpifolia. Nepal: Solitary to
gregarious. In forest of Quercus glauca,
Castanopsis tribuloides, and Symplocus
protolog: INDIA: HIMACHAL PRADESH—Chamba Distr. - Kala Top [2400 m], 16.viii.1985 (paratype, HPUB 3326). Kullu Distr. - Manali [2300 m], 11.viii.1985 T. N. Lakhanpal & A. Kumar s.n. (holotype, HPUB 3188, n.v.; isotype, BPI 71991), s.n. (paratype, HPUB 3202); Pulga [2400 m], 12.viii.1985 unkn. coll. s.n. (HPUB 3229).
RET: INDIA: HIMACHAL
PRADESH—Kullu Distr. -
Manali, 11.viii.1985 T. N. Lakhanpal & A. Kumar
s.n. (holotype, HPUB 3188, n.v.; isotype,
BPI 71991). Shimla Distr. - Baghi,
14.viii.1983 T. N. Lakhanpal & A. Kumar s.n.
(HPUB 511, n.v.; BPI 71988 as
UTTARAKHAND—Chamoli - Bhatwari,
22.viii.1990 V. K. Bhatt & R. P. Bhatt s.n.
(GUH M-19656; RET 299-9); Garhwal - ca. Ransi
Stadium, 4.viii.1993 V. K. Bhatt & R. P.
Bhatt s.n. (GUH M-20033; RET 299-10).
Rudraprayag - Banyakund [2550 m], 28.viii.2015 Tahir
Mehmood 0124 (GUH; RET 717-8, nrITS & nrLSU
DEVELOPMENT REGION—Bagmati Zone - Bhaktapur
Distr., E of Kathmandu, 10 km NE of Bhaktapur
City, 14.vii.1989 Hemanta Ram Bhandary s.n. [RET
NHMTU-box2-10] (NHMTU; RET 355-8), s.n.
[RET NHMTU-box2-9] (NHMTU; RET 355-9), s.n.
[RET NHMTU-box2-7] (NHMTU; RET 355-10).
PAKISTAN: N.W. FRONTIER
PROV.—Hazara Distr. - Kuzagali, 8.viii.1994 A.
N. Khalid 981994 (LAH; RET 140-6), 22.viii.2005
A. R. Niazi 22805 (RET 390-4).
from Tulloss et al. (2001): "All the material reviewed had imperfectly preserved tissues in three critical areas: the lamella trama, the universal veil, and the partial veil. Hence, this species should be considered incompletely known [with regard to some characters;] and its relationship with other rubescent taxa in section Validae must be reviewed when better material is obtained.
"Tulloss (unpub. data) has examined a number of collections of A. rubescens from northern Europe and thinks that A. orsonii is distinct from the European A. rubescens. While the structure of their subhymenia are clearly related, the inflated cells in the sybhymenium of A. rubescens are larger than those seen in the subhymenium of A. orsonii. The spores of A. rubescens are considerably longer and narrower than those of A. orsonii. Comparison of A. orsonii to a number of other rubescent taxa can be derived from data presented by Tulloss and Lindgren (1994).
"A photograph of the Pakistani collection of the present species strongly suggests the watercolor painting of A. rubescens sensu Imazeki & Hongo (1965) and the photographs of the same species in (Imazeki et al., 1988). The penant-shape of the universal veil warts near the margin of the pileus, the orange-pink tint of the flesh of the young stipe, the strong red of the pileus in youth, and the small size of the superior partial veil in the Japanese illustrations all are very similar to the same characters as seen in our photograph. Imazeki et al. (1988) give the spore size for the Japanese material as 8 - 9.5 × 6 - 7.5 µm (est. Q' = 1.30)—much more similar to the data from A. orsonii than to the data from northern European specimens of A. rubescens.
"The spore measurements given by Abraham and Kachroo (1989) for their “A. rubescens” may contain a typographical error with regard to width; for the measurements suggest subglobose spores while the text states that the spores are “short-ellipsoid to subovoid.”
—R. E. Tulloss and K. W. Hughes
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