Amanita sinofulva

Amanita sinofulva Q. Cai, Y.Y. Cui and Zhu L. Yang

Fungal Namber: FN 571588.

Basidioma small to medium-sized. Pileus 3–9 cm diam., plano-convex to applanate, umbonate at center, surface brown (4E6–8) to yellow-brown (5D6–8), often darker at center; volval remnants on pileus absent; margin striate (0.2–0.5 R), non-appendiculate; trama white (1A1), unchanging. Lamellae free, crowded, white (1A1); lamellar edges white (1A1), brownish (4B3–5) to brown (5B3–4); lamellulae truncate, plentiful. Stipe 6–18 cm long × 0.5–1.5 cm diam., slender, subcylindric, slightly tapering upwards, with apex slightly expanded, brown (5B3–4) to brownish (4B3–5); context white (1A1), hollow in center; basal bulb absent; volva saccate, membranous, outer surface white (1A1) with yellow-brown (4B2–4) stains, often yellow-brown (4B2–4) at upper margin, inner surface brownish (5B2–4). Annulus absent. Odor indistinct. Lamellar trama bilateral. Mediostratum 20–40 μm wide, composed of abundant, fusiform, ellipsoid to clavate inflated cells (25–100 × 10–30 μm); filamentous hyphae abundant, 2–10 μm wide; vascular hyphae scarce. Lateral stratum composed of abundant, ellipsoid to fusiform inflated cells (5–15 × 5–15 μm), diverging at an angle of ca. 30° to 60° to mediostratum; filamentous hyphae abundant and 3–8 μm wide. Subhymenium 30–50 μm thick, with 2–3 layers of ellipsoid to fusiform or irregularly arranged cells, 5–20 × 5–20 μm. Basidia 50–70 × 15–20 μm, clavate, 4-spored; sterigmata 6–8 μm long; basal septa lacking clamps. Basidiospores [40/2/2] (10.5–) 11–13.5 (–18) × (9–) 9.5–12 (–13) μm, Q = (1.01–) 1.05–1.23 (–1.34), Qm = 1.14 ± 0.08, subglobose to broadly ellipsoid, occasionally globose or ellipsoid, inamyloid, colorless, thin-walled, smooth; apiculus small. Lamellar edge appearing as a sterile strip, composed of subglobose, ellipsoid to clavate inflated cells (10–30 × 10–25 μm), single and terminal or in chains of 2–3, thin-walled, colorless; filamentous hyphae abundant, 2–8 μm wide, irregularly arranged or ± running parallel to lamellar edge. Pileipellis 50–90 μm thick; upper layer (30–50 μm thick) gelatinized, composed of radially arranged to interwoven, thin-walled, colorless to brownish filamentous hyphae 2–5 μm wide; lower layer (35–50 μm thick) composed of radially arranged filamentous hyphae 3–7 μm wide, colorless to brownish; vascular hyphae scarce. Interior of volval remnants on stipe base composed of longitudinally arranged elements: filamentous hyphae dominant and very abundant, 3–7 μm wide, colorless, thin-walled, branching, anastomosing; inflated cells rare to fairly abundant, subglobose, ellipsoid to fusiform, 40–65 × 15–50 μm, colorless, thin-walled, mostly terminal or sometimes in chains of 2–3. Stipe trama composed of longitudinally arranged, clavate terminal cells, 80–300 × 15–50 μm; filamentous hyphae scattered to abundant, 3–10 μm wide; vascular hyphae scarce. Clamps absent in all parts of basidioma.

Habitat: Solitary to scattered on soil in subtropical forests dominated with Fagaceae, sometimes mixed with Pinus.

Distribution: Known from eastern, central, and southwestern China. Based on the phylogenetic tree inferred from the ITS dataset, it also occurs in Tibet autonomous region and Hunan province.

Specimens examined: (Type) CHINA. YUNNAN PROVINCE: Dali, Nanjian Yizu Autonomous County, in a broad-leaved forest with trees of Fagaceae, altitude 2515 m, 27 June 2015, Kuan Zhao 727 (Holotype, HKAS 92355, GenBank Acc. Nos.: nrLSU = OR042703, ITS = OR042741, rpb2 = OR051738, tef1-α = OR046345). Additional species examined: CHINA. ANHUI PROVINCE: Liuan, Jinzhai County, in a forest dominated with Fagaceae, altitude 1110 m, 21 July 2017, Yan-Jia Hao 1520 (HKAS 100610); same county, in a mixed forest with Castanea seguinii Dode and Pinus taiwanensis Hayata, altitude 840 m, Yan-Jia Hao 1609 (EFHAAU 207); same county, in a mixed forest with Fagaceae and Pinaceae, altitude 1000 m, Yan-Jia Hao 1715 (EFHAAU 313). YUNNAN PROVINCE: Nujiang Lisu Autonomous Prefecture, Lanping Bai and Pumi Autonomous County, in a subtropical forest dominated with Quercus, mixed with Pinus yunnanensis, altitude 2150 m, Gang Wu 743 (HKAS 75058).

Notes: Amanita orientifulva and A. suborientifulva can be confused with A. sinofulva. According to our multi-gene phylogenetic analysis, the first two species also share close relationships with A. sinofulva. However, A. orientifulva has slightly narrower basidiospores (10.0–14.0 × 9.5–13.0 μm, Q = 1.0–1.12, Qm = 1.06 ± 0.04) and is found in subalpine forests dominated by trees of Abies and Picea. The non-umbonate pileus and globose to subglobose or broadly ellipsoid basidiospores of A. suborientifulva set it apart from A. sinofulva. The European A. fulva is also similar to A. sinofulva, but differs in the globose to subglobose basidiospores and in the saccate volva, with inflated cells dominant in its outer part.

Fig.1 Phylogenetic tree of Amanita sect. Vaginatae inferred from maximum likelihood analyses based on the combined dataset (nrLSU, tef1-α and rpb2). Bootstrap values over 50% and Bayesian posterior probabilities over 0.90 are shown along the branches. Sequences from type collections are indicated with (T), and new species are in boldface.