Amanita flavomelleiceps Y. T. Su & Z. H. Chen, 2025

Su, Yu-Ting, Xu, Fei, Zhang, Ping, Deng, Peng-Tao, Lai, Meng-Meng & Chen, Zuo-Hong, 2025, Morphology, multilocus phylogeny, and toxin analysis reveal two new species of Amanita section Amanita (Amanitaceae) from China, MycoKeys 118, pp. 225-244 : 225-244

Amanita flavomelleiceps Y. T. Su & Z. H. Chen sp. nov.

Figs 4 , 5

Etymology.

flavomelleiceps , from flavo = yellow, and melleiceps from Amanita melleiceps , is proposed because this species is similar to Amanita melleiceps but has yellowish, felted volval remnants on the pileus.

Holotype.

China • Sichuan Province, Ganzi Tibetan Autonomous Prefecture, Wuxuhai , altitude 2600 m 10 August 2021, Z. H. Chen, MHHNU 33119 (GenBank accession no. nrLSU: PQ 330908 ; ITS: PQ 326880 ; rpb 2: PQ 356792 ; tef 1 - α: PQ 356798 ; TUB 2: PQ 356795 ).

Description.

Basidioma (Fig. 4 ). small to medium. Pileus 2.5–5 cm diameter, convex to plano-convex, lacking a depression or umbo at center, yellowish (3 A 3–5), yellow (4 A 6–8), to yellowish brown (5 C 7–8), often darker at center and becoming paler towards margin; volval remnants on pileus verrucose to felted, 5–7 mm diameter, dirty yellow (3 A 2–4), randomly arranged; margin striate (0.37–0.41 R); trama white (1 A 1), unchanging. Lamellae free, cream (3 A 1), crowded; lamellulae truncate, plentiful. Stipe 5.5–9 cm long × 0.5–1 cm diameter, cylindric and slightly tapering upwards, with apex slightly expanded, dirty white (2 B 1) to white (1 A 1), sometimes with yellowish (3 A 2–3) tinge, covered with yellowish (3 A 3–5) fibrils; hollow in center; basal bulb subglobose, 0.7–1.5 cm diameter, white (1 A 1) to dirty white (2 B 1); volval remnants on stipe base floccose to granular and short limbate volva on limit between stipe and basal bulb, yellowish (3 A 3–5) to cream (3 A 1). Annulus persistent, subapical to median, yellowish (3 A 2–5) to yellow (4 A 5–8), membranous. Odor indistinct.

Microstructure (Fig. 5 ). Lamellar trama bilateral. Mediostratum 30–50 μm wide, composed of ellipsoid to clavate inflated cells (25–120 × 15–45 μm); filamentous hyphae fairly abundant, 3–7 μm wide; vascular hyphae scarce. Lateral stratum composed of ellipsoid to cylindrical inflated cells (20–70 × 15–30 μm), diverging at an angle of ca. 30 ° – 40 ° to the mediostratum; filamentous hyphae abundant, 3–5 μm wide. Subhymenium (Fig. 5 a ) 40–60 μm thick, with 2–3 layers of subglobose to ellipsoid or irregular cells, 11–25 × 9–20 μm. Basidia (Fig. 5 a ) 40–60 × 14–16 μm, clavate, 4 - spored; sterigmata 3–6 μm long; basal septa lacking clamps. Basidiospores (Fig. 5 b ) [110 / 4 / 1] (7.0 –) 8.0–10 (– 11.5) × (6.0 –) 7.0–9.0 μm, Q = 1.0–1.22, Q m = 1.06 ± 0.006, mostly subglobose, sometimes broadly ellipsoid, inamyloid, colorless, thin-walled, smooth; apiculus small. Lamellar edge appearing as a sterile strip up to 40–80 μm wide in side view, composed of broadly ellipsoid to long ellipsoid inflated cells (10–25 × 8–15 μm), single and terminal or in chains of 2–3, thin-walled, colorless; filamentous hyphae 2–4 μm wide, irregularly arranged or running parallel to lamellar edge. Pileipellis 110–180 μm thick; suprapellis up to 60–90 μm thick, gelatinized, composed of radially arranged, thin-walled, colorless or sometimes yellow-brown filamentous hyphae 2–6 μm wide; subpellis up to 50–70 μm thick, composed of radially and compactly arranged, filamentous hyphae 2–7 μm wide, yellowish or yellow-brown; vascular hyphae scarce. Volval remnants on pileus (Fig. 5 c ) composed of more or less vertically arranged elements; filamentous hyphae scarce, 2–7 μm wide, colorless, thin-walled, branching, anastomosing; inflated cells very abundant to dominant, subglobose or ellipsoid to broadly ellipsoid, 26–85 × 17–55 μm, colorless, thin-walled (≤ 0.05 μm), terminal or in chains of 2–3; vascular hyphae scarce. Interior of volval remnants on the stipe base composed of irregularly arranged elements; filamentous hyphae very abundant, 2–6 μm wide, colorless, thin-walled, branching, anastomosing; inflated cells scarce, subglobose to broadly ellipsoid (26–85 × 17–55 μm). Stipe trama composed of longitudinally arranged, clavate terminal cells, 28–130 × 12–80 μm; filamentous hyphae abundant, 2–5 μm wide; vascular hyphae scarce. Annulus dominantly composed of radially arranged elements; filamentous hyphae very abundant, 2–5 μm wide, colorless, thin-walled, branching, anastomosing; inflated cells scattered to fairly abundant, fusiform to elongate, 20–82 × 12–25 μm. Clamps absent in all parts of the basidioma.

Habitat.

Solitary to scattered on soil in broadleaved forests with Fagaceae ; basidioma occurring in summer.

Distribution.

Currently known from southwestern China, but likely occurs more widely in the region with similar vegetation.

Commentary.

Amanita flavomelleiceps sp. nov. can be easily confused with A. altipes Zhu L. Yang, M. Weiss & Oberw , A. muscaria , and A. melleiceps in their similar appearance and habitats. Amanita altipes was described from China by Yang et al. (2004). It has a bigger basidioma with floccose volval remnants and filamentous hyphae abundant to very abundant, and superior annulus ( Cui et al. 2018). Amanita muscaria is described from Europe ( Gilbert 1940, 1941) and subsequently reported from China ( Yang 2005, 2015). It is characterized by its relatively more robust basidioma with a pileus ca. 5–15 cm, white to dirty-white volval remnants on the pileus, and relatively bigger basidiospores (9.0–12.5 × 7.0–8.5 μm) ( Cui et al. 2018). Amanita melleiceps was described from Japan by Hongo (1966) and subsequently reported from China ( Cui et al. 2018; Yang 2005, 2015). It differs in its honey-yellow pileus, patchy volval remnants on pileus, absent annulus, and relatively narrower basidia (40–55 × 8–11 μm) and basidiospores (8.5–10.5 × 6.0–7.5 μm) ( Yang 2005, 2015; Cui et al. 2018).

Figures

Figure 4. Fresh basidiomata of Amanita flavomelleiceps (MHHNU 33119). Scale bar: 2 cm.

Figure 5. Microscopic features of Amanita flavomelleiceps (MHHNU 33119) a hymenium and subhymenium b basidiospores c longitudinal section of volval remnants on pileus. Scale bar: 20 μm (a); 10 μm (b); 40 μm (c).