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

Figs 6 , 7

Etymology.

Parvisychnopyramis, from parvi = small and sychnopyramis from Amanita sychnopyramis , is proposed because this species is similar to A. sychnopyramis but has smaller basidioma and basidiospores.

Holotype.

China • Yunnan Province, Chuxiong Yi Autonomous Prefecture, Zixi Mountain , in a mixed forest with Fagaceae , altitude 1900 m, 28 July 2021, Z. H. Chen and Y. T. Su, MHHNU 32953 (GenBank accession no. nrLSU: PQ 330907 ; ITS = PQ 326876 ; RPB 2: PQ 356791 ; TEF 1 - α: PQ 356797 ; TUB 2: PQ 356794 ).

Description.

Basidiomata (Fig. 6 ) Small-sized. Pileus 3–4 cm diameter, applanate, center often depressed, light brown (2 B 3–5) to brownish (3 C 3–4), with a brown center (4 C 5–8), becoming pale brownish (2 B 2–3) toward margin; margin striate (0.25–0.39 R); volval remnants conical to subconical, cream colored (3 A 1) to yellowish (1 B 3–4), radially and compactly arranged over the disk but easily removed; trama white (1 A 1), unchanging. Lamellae free, white (1 A 1); lamellulae truncate, evenly distributed. Stipe 7–8 cm long × 0.5–1 cm diam., dirty white (2 B 1) to white (1 A 1), subcylindrical and slightly tapering upwards, with apex slightly expanded, covered with cream (1 A 2) to yellowish (2 A 2) fibrils, often becoming floccose to patchy near basal bulb; context white (1 A 1), fistulose; basal bulb subglobose to ovate, 0.8–1.2 cm diam., volval remnants on stipe base collar-like, or shortly limbate, cream (3 A 1) to yellowish (1 A 3). Annulus present, superior to subapical, pale brownish (2 B 2–4) to dirty white (3 A 1), membranous, fragile. Odor indistinct.

Microstructure (Fig. 7 ), Lamellar trama bilateral. Mediostratum 30–40 μm wide, composed of abundant ellipsoid to long-ellipsoid inflated cells (20–95 × 10–40 μm); abundant filamentous hyphae, 2–4 μm wide; vascular hyphae scarce. Lateral stratum composed of abundant clavate to long-clavate inflated cells (27–65 × 11–25 μm), diverging at an angle of ca. 30 ° – 45 ° toward mediostratum; filamentous hyphae abundant, 3–5 μm wide. Subhymenium (Fig. 7 a ) 25–40 μm thick, with 2–3 layers of subglobose to ellipsoid or irregular cells, 11–27 × 9–25 μm. Basidia (Fig. 7 a ) 35–56 × 11–15 μm, clavate, 4 - spored; sterigmata 3–6 (– 7) μm long; basal septa lacking clamps. Basidiospores (Fig. 7 b ) [100 / 3 / 2] (8.5 –) 9.0–11.0 × 8.0–10.0 μm, Q = 1.0–1.16 (– 1.22), Q m = 1.10 ± 0.08, mostly subglobose and broadly ellipsoid, inamyloid, colorless, thin-walled, smooth; apiculus small. Lamellar edge appearing as a sterile strip, composed of subglobose, broadly ellipsoid to clavate inflated cells (12–25 × 7–15 μm), single and terminal or in chains of 2–3, thin-walled, colorless; filamentous hyphae abundant, 2–4 μm wide, irregularly arranged or running more or less parallel to lamellar edge. Pileipellis 100–125 μm thick; suprapellis up to 60–90 μm thick, gelatinized, composed of radially thin-walled, colorless, filamentous hyphae 2–6 μm wide; subpellis up to 50–75 μm thick, composed of radially and compactly arranged, filamentous hyphae 2–7 μm wide; vascular hyphae scarce. Volval remnants on pileus (Fig. 7 c ) composed of ± vertically arranged elements; filamentous hyphae scarce to fairly abundant, 2–6 μm wide, colorless, thin-walled, branching, anastomosing; inflated cells very abundant to dominant, subglobose, fusiform to ellipsoid (15–62 × 8–55 μm), colorless, thin-walled (≤ 0.05 μm), terminal or in chains of 2–3; vascular hyphae scarce. Interior of volval remnants on stipe base dominantly composed of longitudinally arranged elements; filamentous hyphae very abundant, 2–6 μm wide, colorless, thin-walled, branching, anastomosing; inflated cells fairly abundant, subglobose to broadly ellipsoid or clavate (10–81 × 9–40 μm). Stipe trama composed of longitudinally arranged, clavate terminal cells, 10–171 × 8–50 μm; filamentous hyphae scattered to abundant, 2–6 μm wide; vascular hyphae scarce. Annulus dominantly composed of subradially arranged elements; filamentous hyphae abundant, 2–5 μm wide, colorless, thin-walled, branching, anastomosing; inflated cells fairly abundant, clavate to long ellipsoid (26–118 × 23–59 μm), colorless, thin-walled; vascular hyphae rare. Clamps absent in all tissues.

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 other areas with similar vegetation.

Additional specimen examined.

China • Yunnan Province: Chuxiong Yi Autonomous Prefecture, Zixi Mountain , in a subalpine forest, altitude 1600 m, 25 August 2022, Ping Zhang, MHHNU 11290 .

Commentary.

Amanita parvisychnopyramis sp. nov. also shows some similarities with species in China, including A. collariata Y. T. Su, Zhu L. Yang & Z. H. Chen , A. parvipantherina , and A. sychnopyramis . Amanita collariata was recently described from China ( Su et al. 2022), and this species is distinguished from A. parvisychnopyramis sp. nov. by the granular volval remnants on pileus, volval remnants on the collar-like stipe base, relatively smaller basidia (35–53 × 10–15 μm), and narrower basidiospores (10.0–11.5 × 7.0–9.0 μm) ( Su et al. 2022). Amanita parvipantherina was described from China by Yang et al. (2004) and subsequently reported from India ( Bhatt et al. 2017) and China again ( Yang 2005, 2015; Cui et al. 2018). It is characterized by its small- to medium-sized basidioma, verrucose to pyramidal volval remnants on the pileus, and broadly ellipsoid to ellipsoid basidiospores (8.5–11.5 × 6.5–8.5 μm) ( Yang et al. 2004). Amanita sychnopyramis was described from Japan by Hongo (1971) and subsequently reported from China ( Yang 2005, 2015; Cui et al. 2018). The species is characterized by medium-sized basidioma with a median annulus, volval remnants on the pyramidal pileus, and relatively smaller basidia (30–42 × 8–12 μm) and basidiospores (6.5–8.5 × 6.0–8.0 μm) ( Yang 2005, 2015; Cui et al. 2018).

Figures

Figure 6. Fresh basidiomata of Amanita parvisychnopyramis (MHHNU 32953). Scale bar: 2 cm.

Figure 7. Microscopic features of Amanita parvisychnopyramis (MHHNU 32953) 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).