Amanita concentrica

Amanita concentrica

Basidiomata medium-sized. Pileus 115 mm wide, hemispheric or parabolic when young, then convex to plane at maturity, dry, slightly shiny when moist, white to yellowish white (3A1-2), with pale yellow or butter yellow at center (4A2-3), covered with distinctive universal veil remnants as pyramidal warts up to 4 mm high, crowded over disc, becoming floccose patches toward margin, whitish to light orange, grayish orange to brownish orange (4C3-5A3). Margin slightly striate, not appendiculate with universal veil, sometimes appendicculate with fragments of partial veil. Context 4–9 mm thick above stem, soft to slightly hard, white to orange white (5A1-2). Lamellae 4–8 mm broad, free, crowded, white to yellowish white (3A1-2), lamellulae of 3–6 lengths, truncate to subtruncate. Stipe 95–125 × 1.5–2.3 mm (length includes bulb), tapering upwards, white to pale yellow (1A2-3A1-3), squamulose to scaly, light yellow (3A1-2) at apex, decorated with grayish orange to brownish orange (6B3-6D4) scales at base. Context stuffed to hollow, white to yellowish white (1A1-3A1-2). Bulb subclavate to subnapiform, marginate, up to 35 mm wide, white to yellowish white (3A1-2). Universal veil on stipe base 3–5 concentric rings of whitish, grayish yellow to brownish orange (6B3-6D4) scales on the upper part of the bulb. Partial veil subapical, membranous, white to yellowish white (1A2-3A1-2). Odor not recorded.

Lamellar trama bilateral, divergent, mediostratum 40–60 μm wide. Filamentous hyphae 2–8 μm wide, frequently branching, hyaline, colorless, with terminal cell slightly clavate to subfusiform, 45–130 × 10–25 μm, thin-walled, vascular hyphae rare. Subhymenium (Fig. 3k) 20–45 μm thick. Filamentous hyphae 4–15 μm wide, with some intercalary inflated elements, inflated cells dominating, in 2–3 layers, broadly ellipsoid to ellipsoid to occasionally subfusiform, 9–26 × 8–22 μm. Basidia 43–55 × 6–14 μm, clavate, 4- or (occasionally) 2-spored, with sterigmata up to 6 μm long (Fig. 3k–m). Clamps present. Basidiospores [50/1/1] 7.4–9.7 (–11.4) × (5.7–) 6.5–8.4 (–8.8) μm, (L’ = 8.5 μm, W’ = 7.4 μm, Q = (1.02–) 1.05–1.30 (–1.56), Q’ = 1.16 ± 0.11) (Fig. 3b–j), smooth, hyaline, colorless, thin-walled, inamyloid, subglobose to broadly ellipsoid, occasionally globose or ellipsoid, occasionally adaxially flattened, apiculus rather variable, sublateral, prominent, cylindric to truncate-conic. Contents monoguttulate, white in deposit. Lamellar edge sterile, filamentous hyphae 3–8 μm wide, hyaline, colorless, thin-walled, with slightly inflated segments, inflated cells dominating ovoid to subglobose to ellipsoid, and occasionally broadly clavate, 18–40 × 8–22 μm, hyaline or occasionally with intracellular pale brown pigment. Pileipellis 150–420 μm thick, 2-layered, upper layer 70–220 μm thick, filamentous hyphae 3–5 μm wide, strongly gelatinized, branching, hyaline, colorless, thin-walled, lower layer about 80–200 μm thick, filamentous hyphae 2–4 μm wide, branching, hyaline, thin-walled. Universal veil on pileus filamentous hyphae 4–7 μm wide, branching, hyaline, colorless or occasionally with intracellular pale brown pigment, thin-walled, inflated cells ovoid to ellipsoid dominating, 20–62 × 10–38 μm, vascular hyphae not observed. Universal veil on stipe base filamentous hyphae 2–7 μm wide dominating, hyaline, colorless or occasionally with intracellular pale brown pigment, ovoid to ellipsoid cells, 30–62 × 15–32 μm, vascular hyphae not observed. Stipe trama longitudinally acrophysalidic, filamentous hyphae 2–9 μm wide. Acrophysalides clavate to pyriform, 120–210 × 25–45 μm, vascular hyphae not observed. Partial veil filamentous hyphae 2–5 μm wide, branching, hyaline, colorless.

Habitat: scattered on the ground in forest of Fagaceae.

Specimens examined: THAILAND, Lampang Province, along the road number 1252, 18.935, 99.390833, elev. 1,450 m, 5 July 2013, O. Raspé & B. Thongbai BZ201326 (MFLU 15-0128, BBH 40576).

Distribution: This species was originally described from Japan. It has also been found in China, Nepal, northern India and now Thailand.