Basidiomata solitary, medium size, rather stout, fragile. PILeUS: ranging to 60 mm in diam., plano-convex, brown to dark reddish brown at centre (between ‘cigar brown 16’ and ‘snuﬀ brown 17’), paler in smooth zone outside disc, and paler (‘clay buﬀ 32’) in grooved zone with white inter-striation at margin, glabrous and shiny at centre; MARgIN broadly plicate-striate (>50% of ratio); cONTexT thin, probably white and unchanging; UNIVeRSAL VeIL as scattered friable pyramidal warts whitish at ﬁrst and then gray toward base with yellowish brown (‘buﬀ 52’) tip, easily removed. LAMeLLAe: probably free, sub crowded, relatively narrow, whitish, with concolorous edge; LAMeLLULAe rare. STIpe:
≤80 × 25 mm, tapering in upper portion cylindric in lower part, hollow, cream, fragile, smooth and glabrous; cONTexT white, unchanging; pARTIAL VeIL absent; UNIVeRSAL VeIL as scattered brownish patches at base diﬃcult to distinguish under strong lens (×10) in exsiccatum. Odor and taste not recorded.
BASIDIOSpORes: [90/2/1] (8–)8.5–12(–12.5) × (6.5–)7.5–9.5(–11) µm, L =
10.2–10.8 µm, L’ = 10.4 µm; W = 8.2 µm, W’ = 8.2 µm; Q = (1.03–) 1.06–1.65
(–1.70); Q’ = 1.22–1.32, Qm = 1.25, inamyloid, hyaline, colorless, subglobose to ellipsoid, infrequently elongate or globose, smooth, thin-walled, at least somewhat adaxially ﬂattened, with rounded apex; ApICULUS rounded obtuse to subconic, small, sublateral to subapical; cONTenTS monoguttulate. BASIDIA: 30–44 × 11–13 µm, clavate, with 4 or sometimes 2 sterigmata ranging to 6
µm high; clampless. SUBHyMenIUM: rehydrating weakly; cellular, ≤10–25
µm thick 2(–3) layers, sometimes having very small inﬂated cells from which basidia arise e.g. 10 × 8.5 µm to 14 × 13 µm; wst-near = 8.5–15 µm; wst-far =
≤12–21 µm. LAMeLLA TRAMA: diﬃcult to rehydrate in material, but obviously bilateral; wcs = ≤25 µm or 35 µm; abundant ﬁlamentous hyphae 3–9 µm wide gradually diverging from central stratum, apparently lacking inﬂated hyphae, unbranched or rarely branched; vascular hyphae absent. MARgINAL TISSUe OF LAMeLLAe: diﬃcult to observe, sterile; apparently two layered, yellowish brown, with the outer layer with some globose cells 10 µm in diam., colorless and very few yellowish brown cells approx. 27 × 20 µm and the internal layer consisting of ﬁlamentous hyphae 6 µm wide, parallel to lamella edge. PILeUS cONTexT: moderately well rehydrated, thin; ﬁlamentous hyphae 2.5–8 µm, plentiful, extensively interwoven forming a loose matrix in which other elements occur, commonly branched, septate, clampless; acrophysalides
≤50 × 25 µm, broadly clavate, relatively inconspicuous; vascular hyphae common, traversing the entire context thickness. STIpe cONTexT: diﬃcult to rehydrate, but distinctly acrophysalidic; acrophysalides ≤125–187 × 23–32 µm, plentiful, clavate to slender clavate, thin-walled; ﬁlamentous hyphae 2–13 µm, longitudinally oriented, rarely branched; vascular hyphae 5–8 µm wide, unbranched, with longitudinal orientation, fairly common. PILeIpeLLIS: ≤200 µm thick; suprapellis with hyphae 1.5–5 µm, more or less erect, colorless, thin- walled, immersed in a strong gelatinized matrix; subpellis with hyphae 2.3–7 µm, brown to dark brown, radially oriented; vascular hyphae frequent 7–10 µm, sometimes anticlinal orientation crossing all pileipellis, somewhat arising from pileus context. UnIVeRSAL VeIL: On pileus—mostly absent in exsiccatum, with at least one dark brown thick-walled geometrically globose cell ≤40 µm. On stipe base—common ﬁlamentous hyphae 3–10 µm, densely interwoven, thick-walled, plentiful; terminal globose to pyriform cells with 25–50 × 17–37 µm, grayish to yellowish brown to somewhat brownish, with brownish thick- walled. PARTIAL VeIL: absent.
HABITAT: On soil among members of putatively ectomycorrhizal trees families with the most diverse families being Leguminosae, Myrtaceae, Euphorbiaceae, Sapotaceae, Rubiaceae and Melastomataceae. Polygonaceae and Nyctaginaceae (both probable neotropical ectomycorrhizal forest elements) have relatively small numbers of species (Gentry 1986).
ReMARKS: Amanita chocoana is characterized by its plicate-sulcate pileus
margin, friable grayish pyramidal warts with yellowish buﬀ tips that are pallid at ﬁrst before becoming grayish brown and easily removed by handling, strongly gelatinized suprapellis, and variably shaped (globose to elongate) basidiospores. The new species belongs to small set of taxa of Amanita sect. Vaginatae characterized by a very friable universal veil largely disappearing from the stipe base and from which it is separated as follows:
Amanita colombiana Tulloss et al. from Andean Colombia shares the plicate-sulcate pileus margin topped by somewhat ﬂattened pyramidal to conical velar remnants but diﬀers in the initially fulvous remnants that darken
Priority protection area for Ecuador, because it is an international conservation area shared with Colombia.