Public Description of Amanita augusta Bojantchev & R.M. Davis

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Name: Amanita augusta Bojantchev & R.M. Davis
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Description status: Unreviewed

Taxonomic Classification:

Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Amanitaceae


General Description:

From the original description:

PILEUS 30–150 mm diam., hemispherical to convex when young, plano-convex to planoconcave with age; margin incurved to straight, occasionally ribbed striate near the margin; color dark brown to brown to yellow brown, sometimes yellow to grayish yellow at age, typically paler towards the margin; the universal veil forming rows of concentric warts (finer towards the edge), yellow, but fading to grayish-white with age,
easily removable, often partially or completely washed out or rubbed away, leaving the pileus partially or fully glabrous.
LAMELLAE crowded, 9–20 mm broad, white to yellowish near the cap margin, even, narrowly attached to free; lamellulae common.
STIPE 40–150 mm long, 10–30 mm wide, context stuffed, cylindrical to tapering towards the apex, often with a distinct bulb; color yellow when young, often fading to whitish at age, typically yellowish above the annulus; surface above the bulb forming scaly girdles (finer towards the annulus) with yellow apices, often fading to glabrous at age; surface above the annulus distinctly longitudinally striate.
ANNULUS superior, membranous, pendant, upper surface distinctly striate, thinning, but rarely collapsing with age, typically fimbriate, pale yellow to yellow on both sides, developing darker yellow brown zones at age.
STIPE BASE prominent bulb in most basidiomata,girdled with veil remnants, distinctly rufescent in age.
UNIVERSAL VEIL yellow.
CONTEXT white to pale yellow.
ODOR mild.
TASTE mild.
SPORE DEPOSIT white

BASIDIOSPORES (7.8–)8.5–9.3(–11.2) × (5.2–) 6.0–6.8 (–7.8) µm (mean 8.9 × 6.4 µm), Q = 1.27–1.57, Qav = 1.41 (N = 201, 6 basidiomata, 3 collections), broadly ellipsoid to ellipsoid, slightly to distinctly inequilateral in 30–40% of the cases, with a prominent lateral apiculus, hyaline, amyloid.
BASIDIA 35–62 × 8–12 µm, 4-spored, clavate; sterigmata 4–6 µm long; no clamps observed.
SUBHYMENIAL LAYER composed ofseveral layers of irregular to pyriform cells 9–31 × 7–21 µm, not clamped.
LAMELLAR TRAMA divergent, composed of filamentous to swollen hyphae 6–22 µm wide, no clamps observed.
LAMELLAR MARGINAL CELLS subglobose to sphaeropedunculate 10–33 × 7–21 µm.
PILEIPELLIS an ixocutis of densely interwoven hyphae 2–7 µm wide with the upper layer slightly gelatinized.
ANNULUS composed of filamentous cells, 2–6 µm wide, on the lower surface with clusters of inflated subglobose to pyriform cells, 10–30 × 8–24 µm, with a few inflated cells on the upper surface; clamp-connections not observed.
UNIVERSAL VEIL formed of dense filamentous hyphae 2–8 µm wide, interspersed with broadly ellipsoid to subglobose vesiculose cells, 30–80 × 14–60 µm; no clamps observed.
STIPE TRAMA acrophysalidic, composed of filamentous hyphae 2–6 µm wide and inflated hyphae 62–176 × 16–44 µm; no clamps observed.
OLEIFEROUS HYPHAE abundant, 7–20 µm wide with refractive content.


Diagnostic Description:

Based on private communication with Dimitar Bojantchev,

Compared to A. franchetii, Amanita augusta features:

More saturated colors

  • darker brown cap
  • more distinctly yellow hues on the stipe and annulus
  • more yellow universal veil that remains so into maturity
  • more reddening bulb

Only the European form of A. franchetii f. queletii really may present a challenge as it is darker than the regular A. franchetii v. franchetii. But even then, Amanita augusta is distinctly more color saturated with brown and yellow instead of gray.


Distribution:

Amanita augusta is common in the mixed coastal woods of California, the Pacific Northwest, and Alaska. Reports of collections from the Sierra and Cascade mountain ranges are scarce, particularly in California. The primary fruiting period is autumnal but basidiomata may be collected in the late summer and fall in the Pacific Northwest and in the winter and spring in California. It tends to fruit in small numbers, typically 1-3 basidiomata, rarely more.


Habitat:

Amanita augusta is an ectomycorrhizal species and along the range of its distribution it is found in mixed conifer and broadleaved habitats, amongst a number of potential hosts. The exact associations are not fully mapped out yet, but amongst the established ectomycorrhizal hosts are Bishop Pine (Pinus muricata) and Douglas Fir (Pseudotsuga menziesii), while Western Hemlock (Tsuga heterophyll) is a probable host. In addition, A. augusta has been recorded in solid stands of Coast Live Oak (Quercus agrifolia) in California and Sitka Spruce (Picea sitchensis) in Alaska, as well as in mixed conifer forests that include various pines and Engelmann spruce (Picea engelmannii) in Oregon. Tanoak (Notholithocarpus densiflorus) is a common tree in much of its distribution in California.


Look Alikes:

This species has been confused for many years with the European Amanita franchetii.


References:

1 D. Bojantchev and R. M. Davis, “Amanita augusta, a new species from California
and the Pacific Northwest”, North American Fungi 8:5, 1-11, 2013. ISSN 1937-786X. Available at:

2 D. Viess, Amanita augusta: the Blushing Yellow Veil Amanita, January 2015, http://bayareamushrooms.org/...

3 http://www.amanitaceae.org/?Amanita%20augusta

4 http://www.mykoweb.com/CAF/species/Amanita_augusta.html


Notes:

Much of this content is copied with light edits from the paper by Bojantchev & Davis1 with permission from the lead author.


Description author: Nathan Wilson (Request Authorship Credit)
Description editors: Michael Wood, Joseph D. Cohen


Created: 2013-04-28 13:34:18 MDT (-0600) by Nathan Wilson (nathan)
Last modified: 2015-02-02 08:01:10 MST (-0700) by Joseph D. Cohen (Joe Cohen)
Viewed: 84 times, last viewed: 2019-07-25 06:42:35 MDT (-0600)