Permission to quote extensively from his description of this species
was granted by Dr. Geoffrey Ridley (1991).
Amanita nigrescens has a cap that is 25 - 62 (-90) mm wide and convex to
plano-convex (sometimes with central depression). . Its
colors range from very dark brown in the center to dark
grayish sepia at the margin. In addition there are dark
radially arrange fibrils. The cap is viscid when young or
wet. The margin of the cap can be striate for 12 - 26% of
the cap radius. The flesh of the cap is largely white
with grayish sepia tint below the cap's skin in the cap's
center. The volva on the cap is dark mouse gray to nearly
black and is divided into floccose to smooth patches and
large "squarish warts or crumbs aggregated" in
the cap's center.
The gills of this species are free to adnexed, crowded, and pale
mouse gray near the edge fading to white near their
attachment to the cap. The gills are 4 - 9 mm wide. Short
gills are rounded-truncate to abruptly truncate.
The stem is 37 - 80 (-94) × 4 - 11 (-16) mm with an abrupt, bulbous base 10 - 18 (-22) mm
wide. The stem is whitish buff to buff to very pale
grayish sepia with its surface above the annulus
decorated by very dark brown scales in bands. Similar
scales formed below the annulus are free at their tops.
The annulus is membranous, striate above, very dark brown
to nearly black, skirt-like at first, and eventually
appressed on the stem. The flesh of the hollow stem is
white with occasional pale grayish streaks. The volva on
the bulb forms a felted, dark mouse gray, sheathing limb.
Odor and taste were not reported for this species.
The spores of this species measure 8 - 13 × 8 - 13 µm and are globose and inamyloid.
Clamps are present at bases of basidia.
Amanita nigrescens is found only in New Zealand in association with Nothofagus.—R. E. Tulloss
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
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).
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 material is predominantly based on the revision of G. S. Ridley (1991) with some additions (as marked below) using data from original research by R. E. Tulloss.
Basidiocarps very small to medium. or occasionally large.
From the protolog (Ridley 1991): 25 - 62 (-90) mm, plano-convex to plano-depressed, with disc fuscous, paling to dark grayish sepia at margin, apparently overlain with dark radiating fibrils, viscid when wet or young, drying with age; context white, with grayish-sepia region immediately below pileipellis in disc, with gray line immediately above lamellae; margin sulcate (0.10 - 0.25R), entire, occasionally ragged; universal veil dark mouse-gray to fuscous black, as either floccose to smooth patches or large squarish warts or crumbs aggregated about disc.
From the protolog (Ridley 1991): free to adnexed, crowded, pale mouse-gray, paling to white at line of contact with pileus context, 4 - 9 mm broad, with margin entire to slightly crenulate and fuscous to fuscous black; lamellulae rounded to abruptly truncate.
From the protolog (Ridley 1991): 37 - 80 (-94) × 4 - 11 (-16) mm, whitish-buff to buff, to very pale greyish sepia, with surface breaking into fuscous, striate, band-like scales above partial veil, fibrillose with apically free, fuscous scales below partial veil, with such decoration becoming membranous and band-like towards stipe base; context white, with sparse smoke-gray streaks, hollow above bulb; bulb abrupt, 10 - 18 (-22) mm wide; partial veil membranous, striate, fuscous to fuscous black, pendulous then adhering to stipe; universal veil as felted, mouse-gray, sheath around upper part of stipe's basal bulb or as very small limb on bulb.
From the protolog (Ridley 1991): 40 - 80 µm thick, with suprapellis gelatinized, with subpellis not gelatinized.
From the protolog (Ridley 1991): 41 - 68 × (9.0-) 12.0 - 17.0 µm, 4-spored, occasionally 1- to 3-spored; clamps present.
From the protolog (Ridley 1991): On pileus: hyphae abundant, branched, 3 - 10 µm wide, dark umber, irregularly arranged; inflated cells abundant ellipsoid to ovoid to pyriform to clavate to globose, 17.0 - 126 × 13.5 - 102 µm, singly or in chains; clamps present. On stipe base: not described. [Note: a dark universal veil in which the hyphae are pigmented and the inflated cells are not is very unusual in Amanita. Perhaps, the protolog contains an omission or typographical error on this point.—ed.]
lamella edge tissue
From the protolog (Ridley 1991): inflated cells numerous, 16 - 48 × 10.5 - 26 µm, clavate to sphaeropedunculate, umber.
From the protolog (Ridley 1991): [80/6/-] 8.0 - 13.0 × 8.0 - 13.0 µm,(Q = 1.0 - 1.05; Q' = 1.0), hyaline, thin-walled, ??, inamyloid, globose; apiculus not described; contents not described; white in deposit.
From the protolog (Ridley 1991): Solitary to subgregarious. Under Nothofagus truncata on North Island, New Zealand.
From the protolog (Ridley 1991): NEW ZEALAND: GISBORNE—Urewera Nat. Pk., Waikaremoana, ca. park HQ, 29.v.1983 N. Sutherland s.n. [G. Stevenson 83/166] (CHR).
WELLINGTON—Rimutaka For. Pk., Orongorongo Valley, Paua Ridge, 8.iv.1987 G. S. Ridley 392 (PDD 56136), 22.iv.1987 G. S. Ridley 414 (PDD 56137), 429 (PDD 56138), 29.iv.1987 G. S. Ridley 443 (PDD 56139), 12.i.v.1988 G. S. Ridley 614 (PPD 56140); Wairarapa, 27.vi.1949, A. Crawford s.n. [G. Stevenson 682] (holotype, K).
Prior to Ridley's revision of the species, Amanita nigrescens was known only from the type specimen.
—R. E. Tulloss
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can be found here.
1. Amanita nigrescens, New Zealand.
Dr. Karl Soop - (1) New Zealand (field identification by Dr. G. S. Ridley).
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.