Agaricales » Amanitaceae » Amanita

Amanita hemibapha

Amanita hemibapha (Berk. & Broome) Sacc.

Index Fungorum number: IF 202755

Basidioma medium-sized. Pileus 6–12 cm diam., plano-convex with the center slightly depressed, orange-red (6A6–8) to lemon yellow (3B8) at center, and becoming vivid yellow (3A7–8) to pale yellow (3A3–4) towards the margin; universal veil on pileus white patch; margin striate (0.3 R), non-appendiculate; context 5 mm wide, white (1A1) to yellowish white (2A2), unchanging. Lamellae free, crowded, cream white (1A1–2); lamellulae truncate. Stipe 7–10.5 × 0.5–1.5 cm, cylindrical, covered by light yellow to vivid yellow (2A5–8) fibrous squamules; context broadly fistulose, white (1A1). Bulb absent. Universal veil on stipe base saccate, membranous, up to 4 cm high, white (1A1). Partial veil subapical, fragile, vivid yellow (3A7–8). Lamellar trama bilateral, divergent; mediostratum 25–40 μm wide, filamentous hyphae abundant, 2–8 μm wide; clavate to ellipsoidal inflated cells 70–98 × 20–23 μm; vascular hyphae scarce. Subhymenium 20–35 μm thick in 2–3 layers, with subglobose to ellipsoidal or irregular cells, 6–25 × 5–15 μm. Basidia 32–50 × 8–12 μm, clavate, 4-spored with sterigmata 3–5 μm long; clamps present at base. Basidiospores (7.0–) 7.5–11.0 (–12.0) × 5.5–7.0 μm, Q = 1.23–1.64 (–1.71) μm, Qm = 1.44 ± 0.13, broadly ellipsoid to ellipsoid, sometimes elongate, inamyloid, hyaline, thin-walled, smooth; apiculus small. Lamellar edge sterile; filamentous hyphae 1–5 μm wide, hyaline, thin-walled; inflated cells, with subglobose, ovoid to ellipsoidal, 14–40 × 12–30 μm, single and terminal or in chains of 2–3, hyaline, thin-walled. Pileipellis 60–110 μm thick; 2-layered, upper layer 15–35 μm thick, filamentous hyphae 1–5 μm wide, weakly gelatinized, branching, thin-walled, hyaline; lower layer 50–85 μm thick, filamentous hyphae 2–7 μm wide, branching, thin-walled, hyaline to light yellow; vascular hyphae rare. Inner surface of universal veil on stipe base filamentous hyphae dominant 1–9 μm wide, hyaline to light yellow, thin-walled, branching; inflated cells, with subglobose, pyriform to clavate, 30–85 × 20–54 μm, hyaline, thin-walled; vascular hyphae rare. Outer surface of universal veil on stipe base similar to structure of inner part, but presenting more abundant inflated cells. Stipe trama longitudinally acrophysalidic; filamentous, undifferentiated hyphae 1–12 μm wide, thin-walled, frequently branching; acrophysalides 65–190 × 25–65 μm, thin-walled; vascular hyphae rare. Partial veil filamentous hyphae very abundant, 2–9 μm wide, hyaline, thin-walled; inflated cells scarce to locally abundant, globose, subglobose to clavate, 22–70 × 9–25 μm, hyaline to light yellow, thin-walled; vascular hyphae rare. Clamp connections present in all tissues of basidioma.

Habitat: Solitary to scattered on soil in tropical deciduous forests dominated by Dipterocarpus and Shorea.

Distribution: known from China, India, Sri Lanka, and Thailand, this study.

Specimens examined: Thailand, Chiang Mai Province, Mae Taeng District, 19°07′45″ N 98°45′51″ E, alt. 1421 m, 9 August 2019, Yuan S.L., STO-2019-477 (SDBR-CMUSTO-2019-477); Doi Saket District, 18°53′2″ N 99°9′17″ E, alt. 343 m, 26 July 2020, Kumla J. and Suwannarach N., CMUNK0819 (SDBR-CMUNK0819), 11 August 2020, Kumla J. and Suwannarach N., CMUNK0857 (SDBR-CMUNK0857); Lumphun Province, Mueang District, Chiang Mai University Haripunchai Campus, 18°30′10″ N 99°8′25″ E, alt. 400 m, 25 July 2020, Suwannarach N., CMUNK0776 (SDBR-CMUNK0776).

Notes: The remarkable features of A. hemibapha include the fact that this species has a reddish yellow or orange-red tone in the center of its pileus that becomes vivid yellow or pale yellow towards the edges. This species is also known to have a yellow annulus. Amanita hemibapha was firstly reported from Sri Lanka, and then found in China, India and Thailand. Morphologically, A. hemibapha is easily confused with A. caesareoides Lj. N. Vassiljeva, A. kitamagotake N. Endo & A. Yamada, A. rubroflava Y.Y. Cui, Q. Cai & Zhu L. Yang and A. subhemibapha Zhu L. Yang, Y.Y. Cui & Q. Cai. However, A. caesareoides, A. kitamagotake, and A. rubroflava differ from A. hemibapha by having a distinctly umbonate pileus, a much darker and reddish tone in the pileus center and relatively broader basidiospores [3,4,58]. Amanita subhemibapha, originally reported from China, differs from A. hemibapha by having a lighter yellowish tone pileus and relatively broader basidiospores (8.0–11.0 × 6.0–8.0 μm). According to illustrations of the Thai specimens, most of them are orange-red to lemon yellow at the center of the pileus. This feature was different from the original description of A. hemibapha due to the presence of red to orange-red in the center of the pileus. This may be influenced by the phenotypic variability that exists across a wide geographic range. However, the sizes of basidiomata, other macroscopic and microscopic features of the Thai specimens agree well with descriptions of previous studies. Hence, we identify our specimens as A. hemibapha using a combination of morphological and molecular data.

Fig. 1 The phylogenetic tree derived from maximum likelihood analysis of 64 specimens of the combined ITS, nrLSU, rpb2, and tef-1 genes. The tree is rooted with A. retenta and A. shennongjiana. Numbers above branches are the bootstrap percentages (left) and Bayesian posterior probabilities (right). Bootstrap values ≥ 75% and Bayesian posterior probabilities ≥ 0.90 are shown. The scale bar displays the expected number of nucleotide substitutions per site. Sequences derived in this study are shown in red. Type species are shown in bold.