Amanita rufobrunnescens W. Q. Deng & T. H. Li, 2016

Deng, Wangqiu, Li, Tai Hui & Hosen, Md. Iqbal, 2016, Amanita rufobrunnescens, a new species of Amanita section Amidella from South China, Phytotaxa 243 (2), pp. 147-154 : 148-150

Amanita rufobrunnescens W. Q. Deng & T. H. Li , sp. nov. Figs. 1 , 2

MycoBank: MB 814611

Diagnosis:—Basidiomes small to medium. Pileus 40–100 mm broad, white to whitish, changing to reddish, light brown to reddish brown when bruised; with some brownish volval remnants, striate at margin; lamellae white bruising light brown to reddish brown, lamellulae truncate; stipe white to whitish; volva 35–60(–120) × 25–50(–75) mm, grayish orange to light brown; basidiospores (9.5–)10–12(–13) ×(5–)5.5–6.5(–7) μm, amyloid; clamp connections absent.

Type:— CHINA. Guangdong Province: Guangzhou City, Tianluhu Mountain, in broad-leaved forests, at 113°25′E, 23°13′N, alt. 226 m, 27 June 2014, Xia YW & Song ZP (GDGM 42374, holotype!).

Sequences ex holotype:—KT865208 (ITS), KT865210 (LSU).

Etymology:— rufobrunnescens (Lat.) : referring to the changing color on bruising of the new species.

Macroscopic characters:— Basidiomes small to medium-sized. Pileus 40–100 mm diam, sub-globose, then convex to applanate, whitish or dirty white, dry; margin radially striate (0.15–0.25 R); volval remnants thin, sub-membranous to radially fibrillose, brownish orange (6C4–6), light brown (6D4–6) to brown (6E4–6); trama white, 4–6 mm thick at stipe, changing to reddish, light brown to reddish brown (7A2, 7D5–8E5) on exposure to air or on bruising. Lamellae subfree to adnate, crowded, white, changing to light brown to reddish brown (7D5–8D5) on bruising, becoming grayish brown (6E3–6F3) when dried, 8–12 per cm at pileus margin, 3–6 mm wide; lamellulae truncate, plentiful, evenly distributed. Stipe 70–150 mm long, 7–22 mm thick at apex, sub-cylindrical or slightly tapering upward, white to whitish, densely covered with white squamules; context white, changing to light brown to reddish brown (7D5–8D5) on bruising, hollow in center; basal bulb lacking; volva saccate, 35–60(–120) × 25–50(–75) mm, outer surface grayish orange (6B3–4) or light brown (6D4–7), inner surface whitish, 3–13(–16) mm thick. Annulus fragile and easily broken, and its remains forming farinose squamules on the upper part of the stipe. Taste and odor not distinctive.

Microscopic characters:— Lamellar trama bilateral. Mediostratum 30–50 μm wide, composed of abundant ellipsoidal to cylindrical cells (30–135 × 12–30 μm), mixed with 3–9 μm wide filamentous hyphae. Lateral stratum made up of abundant clavate to sub-ellipsoid inflated cells (28–90 × 12–30 μm), mixed with 3–8 μm wide filamentous hyphae. Subhymenium 40–60 μm thick, with 2–3 layers of sub-globose, ovoid to irregularly shaped cells (13–25×10–20 μm). Basidia 35–50 × 9–11 μm, clavate, 4-spored; sterigmata 3–7 μm long. Basidiospores [100/5/2] (9.5–)10–12(–13) ×(5–)5.5–6.5(–7) μm (Q=1.5–2.0 (–2.2), Q m =1.78± 0.17), mostly elongate, occasionally ellipsoidal or cylindrical, amyloid, colorless, hyaline, thin-walled, smooth. Lamellar edge sterile, composed of inflated cells and filamentous hyphae; inflated cells 12–30 × 8–15 μm, broadly clavate or sub-globose to ellipsoid, single and terminal or in chains of 2–3, thin-walled, colorless, hyaline or with yellowish contents; filamentous hyphae not abundant, 3–8 μm wide, thin-walled, hyaline or with yellowish pigments. Pileipellis 120–180 μm thick, two-layered; upper layer 50–80 μm thick, gelatinized, composed of sub-radially arranged, (3–)5–10 μm wide, filamentous to cylindrical hyphae with yellowish vacuolar pigments; lower layer 70–100 μm thick, non-gelatinized, composed of radially and compactly arranged hyphae 5–15 μm wide colorless to sub-colorless, thin-walled. Volval remnants on pileus composed of very abundant 5– 15 μm wide, colorless to sub-colorless, thin- to slightly thick-walled filamentous hyphae; inflated cells fairly abundant, subglobose or ellipsoid to fusiform, 50–110 × 15–45 μm, hyaline to sub-hyaline, thin- to slightly thick-walled. Volval limb on stipe base made up of filamentous hyphae and inflated cells. Outer surface of the limb gelatinized, composed of irregularly arranged filamentous hyphae, 6–10 μm wide, light yellowish brown, thin- to slightly thick-walled. Interior of volval limb composed of two layers intergrading into each other. Outer layer composed of longitudinally to irregularly arranged elements: filamentous hyphae very abundant, (3–)6–12(–15)μm wide, colorless, hyaline or sometimes with light yellowish brown contents, thin- to slightly thick-walled, branching; inflated cells scattered to fairly abundant, clavate to sub-globose, 20–65 × 15–30 μm, colorless, hyaline or with light yellowish brown contents, slightly thick-walled, usually single and terminal; oleiferous hyphae scattered to locally conspicuous, 6–18 μm wide. Inner layer composed of very abundant (3–)5–12 μm wide, colorless, hyaline, thin- to slightly thick-walled filamentous hyphae; inflated cells fairly abundant to locally abundant, sub-globose or ellipsoidal to fusiform, 45–120 × 25–50 μm, hyaline to sub-hyaline, thin- to slightly thick-walled. Inner surface of the limb gelatinized, composed of 6–15(–20) μm wide filamentous hyphae, colorless to yellowish, thin-walled. Stipe trama composed of longitudinally arranged inflated cells and filamentous hyphae; inflated cells cylindrical or long clavate, terminal cells 100–270 × 25–40(–50) μm; filamentous hyphae abundant, 5–15(–20) μm wide, colorless to sub-colorless, thin-walled. Clamp connections absent in all tissues.

Habit, habitat and distribution:—Scattered on soil, in subtropical broad-leaved forests dominated by Castanopsis fissa , alt. 200– 300 m. Known only from southern China.

Additional specimen examined:— CHINA. Guangdong Province: Guangzhou City, Tianluhu Mountain, in broad-leaved forests, 04 July 2014, Deng WQ and Song ZP (GDGM 44638, paratype!).

Sequences ex paratype:—KT865209 (ITS), KT865211 (LSU).

Figures

FIGURE 1. Basidiomata of Amanita rufobrunnescens (a–c. from GDGM 42374, holotype; d–f. from GDGM 44638). Bars = 2 cm. Photos by Ye-Wei Xia and Zong-Ping Song.

FIGURE 2. Microscopic features of Amanita rufobrunnescens (GDGM 42374). a. Hymenium and subhymenium. b. Basidiospores. c. Longitudinal section of the inner layer of the interior of the volval limb at stipe base. d. Longitudinal section of the outer layer of the interior of the volval limb at stipe base. Scale bars: a, b = 10 μm; c, d = 20 μm. Drawings by MD. Iqbal Hosen.