Amanita albicarnosa Yuan S. Liu & S. Lumyong, 2022

Liu, Yuan S., Kumla, Jaturong, Suwannarach, Nakarin, Sysouphanthong, Phongeun & Lumyong, Saisamorn, 2022, Three species of Amanita section Lepidella (Amanitaceae, Agaricales) from northern Thailand, Phytotaxa 570 (1), pp. 16-28 : 20-23

Amanita albicarnosa Yuan S. Liu & S. Lumyong sp. nov. Figure 1a, 1b and 3

MycoBank number: 844132

Etymology: albicarnosa , from albus = whitish, and carnosus = flesh-colored, refers to the white pileus and fleshcolored lamellae of this species.

Holotype: THAILAND. Chiang Rai Province: Mueang District, Nang Lae , N 20°01’32’’, E 99°52’19’’, alt. 397 m, 2 May 2020, Yuan S. Liu, STO-2020-003 (CMUB-39971, GenBank accession no.: nrLSU = ON695876 , ITS = ON695869 , RPB2 = ON704631 , TEF1 -α = ON704634 and TUB = ON704637 ).

Diagnosis: Amanita albicarnosa is recognized by having small to medium-sized basidiomata; a white to yellowish white pileus covering floccose to patchy or felted, white to pale yellow volval remnants; a subcylindrical stipe coving fibrillose white scales, and a fugacious subapical annulus, as well as the present clamp.

Description: Basidiomata small to medium-sized. Pileus 2.4–5.3 cm diam., convex to applanate, white (1A1) to yellowish white (4A2); volval remnants on pileus floccose to patchy or felted, white (1A1) to pale yellow (4A3), densely arranged on the disk; margin non-striate; context white, unchanging. Lamellae free, crowded, white (1A1) to orange white (5A2); lamellulae attenuate. Stipe 4.1–9.1×0.6–1.0 cm (length includes bulb), subcylindrical and slightly tapering upward, with apex slightly expanded, white (1A1) to pale yellow (4A3), coving fibrillose white (1A1) scales; context fistulose, white (1A1); basal bulb not obvious, sometimes fusiform or ventricose, 0.8–1.2cm diam., covering fibrillose, white (1A1) to pale yellow (4A3) volval remnants. Annulus superior, fragile, white (1A1). Odor not recorded.

Lamellar trama bilateral. Mediostratum 10–25 μm wide, composed of abundant clavate to fusiform inflated cells (30–75 × 6–11 μm); filamentous hyphae fairly abundant to abundant, 1–4 μm wide; vascular hyphae scarce. Lateral stratum 10–30 μm wide, composed of abundant clavate to sub-cylindrical inflated cells (35–65 × 5–13 μm), diverging at an angle of ca. 30° to 45° to mediostratum; filamentous hyphae fairly abundant, 3–5 μm wide. Subhymenium 10–25 μm thick, with 2–3 layers of subglobose, pyriform, or irregular cells, 8–17 × 7–13 μm. Basidia ( Figure 3b ) 40–50 × 8.5–13 μm, clavate, 4-spored; sterigmata 2–3.5 μm long; basal septa clamped. Basidiospores ( Figure 3a ) [100/3/2] (6) 7–9 (9.5) × 5–7 μm, avl X avw = 8.0 × 6.0 μm, Q = 1.15–1.55(1.70) μm, Qm = 1.34 ± 0.12, broadly ellipsoid to ellipsoid, amyloid, orange white, thin-walled, smooth; apiculus small. Pileipellis 90–145 μm thick, composed of radial, thin-walled, greyish yellow to dark yellow, filamentous hyphae 4–10 μm wide; vascular hyphae scarce. Volval remnants on pileus ( Figure 3c ) composed of irregularly arranged elements: filamentous hyphae scattered to abundant, 3–8 μm wide, light brown to yellowish brown, thin-walled, branching, anastomosing; inflated cells very abundant to dominant, subglobose, pyriform, clavate to fusiform, sometimes irregular, 33–150 × 8–28 μm, thin-walled; vascular hyphae scarce. Volval remnants on stipe base is semblable with the structure of volval remnants on pileus, filamentous hyphae scattered to abundant, 1–7 μm wide, thin-walled, branching, anastomosing; inflated cells very abundant to dominant, ellipsoid, clavate to sub-cylindrical, 23–135 × 8–32 μm, thin-walled; vascular hyphae scarce. Stipe trama composed of longitudinally arranged elements: filamentous hyphae dominant, 3–14 μm wide; inflated cells fairly abundant, ellipsoid, clavate to sub-cylindrical, 70–130 × 12–28 μm; vascular hyphae scarce. Clamps present in all parts of basidiomata.

Habitat: Solitary to scattered in the rice stubble field. Basidiomata occur at the beginning of the rainy season, April to May.

Distribution: Currently known from northern Thailand (Chiang Rai Province).

Additional collections examined: THAILAND. Chiang Rai Province: Mueang District , N 20°01’32’’, E 99°52’19’’, alt. 397 m, 2 May 2020, Yuan S. Liu, STO-2020-001 (SDBR- STO-2020-001, GenBank accession no.: nrLSU = ON695875 , ITS = ON695868 , RPB2 = ON704630 , TEF1 -α = ON704633 and TUB = ON704636 ); STO-2020-004 (SDBR- STO-2020-004, GenBank accession No.: nrLSU = ON695877 , ITS = ON695870 , RPB2 = ON704632 , TEF1 - α = ON704635 and TUB = ON704638 ) .

Remarks: Our phylogenetic analyses ( Figure 2 ) showed that Amanita albicarnosa is closely related to A. inopinata , A. pruittii , A. quitensis and A. singer . However, A. Amanita inopinata has a larger cap entirely covered with the thick, cottony, pale gray-brown felt which disrupts into very prominent darker pyramidal warts ( Reid 1987); Amanita pruittii has a very small to very large cap (2.0–15.0 cm) and much longer and wider stipe (3.0–15.0 × 6.0–4.0 cm), appears to be much stronger than A. albicarnosa ( Tulloss et al. 2014) ; Amanita quitensis ( Crous et al. 2018) was firstly reported from Ecuador and this species appears under thick, dense, hard, scale-shaped warts on its white pileus, as well as the globose or rarely subglobose basidiospores (6.0–12.0 × 6.5–9.5 μm, Q = 1.04 μm); Amanita singer , originally described from Argentina, has the white to greyish white pileus, the rather inconspicuous volva remnants on the cap and the particular salmon-colored gills ( Bas 1969).

Figures

FIGURE 1. Fresh basidiomata of the studied Amanita species and location of the sampling sites. a–b: A. albicarnosa (CMUB-39971, holotype). c: A. aureofloccosa (SDBR-STO-2020-PS39). d: A. manicata (SDBR-STO-2020-34). e: Location of the sampling sites. Scale bars: a–b=3 cm, c=8 cm, d=5 cm.

FIGURE 2. RAxML tree based on nrLSU-ITS dataset. Bootstrap values (BS) for ML ≥ 50% and posterior probabilities (PP) for BI ≥ 0.95 are placed above or below the branches respectively. Newly generated sequences are indicated in red. The tree is rooted with Limacella bangladeshana (CMU-JK0146, CMU-NK0356 & HKAS 75316).

FIGURE 3. Amanita albicarnosa (CMUB-39971, holotype). a: Basidiospores. b: Hymenium and subhymenium. c: Longitudinal section of volval remnants on pileus. Bars: a=5 μm, b=40 μm, c=40 μm.