Amanita orientisororia T. Bau & Zhu L. Yang, 2021

Liu, Xiaoliang, Bau, Tolgor & Yang, Zhu L., 2021, A new saprotrophic species of Amanita (Amanitaceae, Agaricales) from Inner Mongolia, China, Phytotaxa 527 (4), pp. 284-292 : 287-290

Amanita orientisororia T. Bau & Zhu L. Yang , sp. nov. ( Figs. 2 , 3)

MycoBank number:841290

Diagnosis:—Basidiomata small. Pileus 20–60 mm in diam, surface white (1A1) to greyish white (1B1); white (1A1) volval remnants on pileal surface conical to subconical to pyramidal. Stipe 40–70 mm long, 7–12 mm diam., subcylindrical, densely covered with concentrically arranged appressed to recurved greyish white (1B1) somewhat milk white (1A2) squamules. Annulus superior, membranous, white (1A1) to greyish white (1B1). Basidiospores broadly ellipsoid to ellipsoid, amyloid, 9–13 (15) × (6) 7–9.5 (10) μm. Clamps common.

Etymology:— orientisororius, referring to its smaller basidiomata occurring in East Asia in comparison with those of A. vittadinii , a putatively related species found in Europe and North Africa.

Types:— CHINA. Inner Mongolia Autonomous Region: Xarmoron Park , Tongliao City , 43° 38′ 15″ N, 122° 16′ 2″ E, elev. 183m, 10 Aug. 2018, Tolgor Bau , HMJAU59015 (holotype!), same location, 43° 37′ 52″ N, 122° 15′ 33″ E, elev. 180m, 18 Aug. 2018, Tolgor Bau, HMJAU59016 (paratype!) .

Description:—Basidiomata ( Fig. 2 , 3) small, rarely medium-sized. Pileus 20–60 mm in diam., convex to applanate, surface white (1A1) to greyish white (1B1); volval remnants on pileal surface conical to subconical to pyramidal, up to 2–3 mm in height and 3–4 mm in diam., white (1A1) to milk white (1A2), upper half often pale to yellowish white (2A2); margin non-striate, appendiculate; trama white (1A1), unchanging when injured. Lamellae free or nearly free, white, milk white (1A2) to yellowish white (2A2), lamellulae attenuate. Stipe 40–70 mm long, 7–12 mm diam., subcylindrical, white (1A1) to pale yellowish white (2A2), densely covered with concentrically arranged appressed to recurved pale yellowish white (2A2) squamules; context white (1A1), unchanging when injured; stipe base nearly cylindrical or attenuate downwards, 7–14 mm diam., upper half covered with floccose, white (1A1) to greyish white (1B1) to yellowish white (2A2) squamules. Annulus superior, membranous, white (1A1) to greyish white (1B1), upper surface striate, lower surface often with floccose, greyish white (1B1) to milk white (1A2) warts. Odor unknown.

Lamellar trama bilateral. Mediostratum composed of abundant fusiform to clavate inflated cells (16–23 μm wide), mixed with abundant filamentous hyphae (5–10 μm wide), lateral stratum made up of abundant clavate to subclavate inflated cells (14–25 μm wide), mixed with 4–11 μm wide filamentous hyphae. Basidia ( Fig.4 ) 35–47 × 9–12.5 μm, clavate, 4– or 2– spored; sterigmata 4–6 μm long. Basidiospores ( Fig.4 ) [80/4/3] (8.5) 9–13 (15) × (6) 7–9.5 (10) μm, Q = (1.20) 1.22–1.54 (1.60), Qm = 1.38 ± 0.10, broadly ellipsoid to ellipsoid, amyloid, slightly thickwalled, colorless and hyaline, smooth. Lamellar edge appearing as a sterile strip, composed of numerous subglobose to clavate or broadly clavate inflated cells, usually single and terminal or in chains of 2–3, thin–walled, colorless, hyaline; filamentous hyphae rare, thin–walled, hyaline or with yellowish contents. Volval remnants on pileus ( Fig. 4 ) composed of vertically arranged elements: inflated cells very abundant to dominant, subfusiform to elongate-ellipsoid, occasionally subglobose, 35–110 × 15–30 μm, colorless and hyaline; filamentous hyphae scattered to locally abundant, 3–6 μm wide; vascular hyphae rare 3–7μm wide. Pileipellis composed of subradially arranged cylindrical hyphae 4–13 μm wide, barely gelatinized. Stipe trama composed of longitudinally arranged elements: inflated cells dominant, often in short chains, sometimes terminal, 150–250 × 10–30 μm; filamentous hyphae 3–7 μm wide, scattered, branching and anastomosing, occasionally clamped; vascular hyphae rare, 3–10 μm wide. Clamps present in all parts of basidiomata, but more common in lamellae.

Habitat and distribution:—Solitary or scattered on grass lawn or sand dunes; occurring in summer and fall; known from Northeastern China.

Additional specimen examined:— CHINA. Inner Mongolia Autonomous Region: Xarmoron Park, Tongliao City , 43° 38′ 21″ N, 122° 16′ 7″ E, elev. 188m, 5 Sep. 2021, Tolgor Bau, HMJAU59017 .

Figures

FIGURE 4. A. Basidia and subhymenium B. Basidiospores C. Volval remnants on pileal surface. Bars A=10 μm, B=20 μm, C=30 μm. Drawings by Zhu L. Yang.

FIGURE 2 and 3. Basidiomata of Amanita orientisororia on grassland (HMJAU59015) and vertical section of A. orientisororia (HMJAU59016) Bars A, B=10 mm Photos by Tolgor Bau.