Amanita kalasinensis Yuan S. Liu & S. Lumyong
Mycobank number: 842342.
Basidioma small to medium-sized. Pileus 3.0–5.7 cm diam., convex, planoconvex to applanate, slightly depressed at center, white (1A1) to greyish yellow (4B3–5), often darker at center and becoming paler towards margin; volval remnants on pileus conical, pyramidal to granuliform, 1–2 mm dia., white (1A1) to yellowish white (4A2), densely arranged on the disk; margin striate (ca. 0.3–0.5), non-appendiculate; context white, unchanging. Lamellae free, crowded, white (1A1); lamellulae truncate, plentiful. Stipe 3.5–8.0 cm long _ 0.6–0.9 cm diam., subcylindrical and slightly tapering upward, with apex slightly expanded, white (1A1) to yellowish white (4A2), sometimes with greyish yellow (4B3–4) tinge, covered with white (1A1) fibrils, often becoming floccose near basal bulb; context white (1A1), stuffed; basal bulb globose to subglobose, 0.9–1.4 cm diam., white (1A1); volval remnants on stipe base granuliform to floccos, white (1A1) to light yellow (4B4–5). Annulus absent. Odor not recorded. Lamellar trama bilateral. Mediostratum 15–20 µm wide, composed of abundant clavate to cylindrical inflated cells (54–145 × 13–30 µm); filamentous hyphae abundant, 4–12 µm wide; vascular hyphae scarce. Lateral stratum composed of abundant ellipsoid to clavate inflated cells (32–66 × 13–37 µm), diverging at an angle of ca. 30 µm to 45 µm to mediostratum; filamentous hyphae abundant to very abundant, 3–10 _m wide. Subhymenium 20–30 µm thick, with 2–3 layers of globose, ellipsoid, or irregular inflated cells, 6–24 × 6–18 µm. Basidia 37–52 × 12–16 µm, clavate, four-spored; sterigmata 4–6 µm long; basal septa clamped. Basidiospores [100/3/3] (8.5–) 9.0–11.5 (–13.0) × (6.0–) 7.0–8.5 (–10.0) µm, avl × avw = 10.3 × 7.4 µm, Q = (1.19–) 1.25–1.53 (–1.67) µm, Qm = 1.40 × 0.09, broadly ellipsoid to ellipsoid, inamyloid, colorless, thin-walled, smooth; apiculus short but wide, width up to 1.5 µm. Lamellar edge appearing as a sterile strip, composed of very abundant to nearly dominant globose, subglobose, ellipsoid, or irregular inflated cells (11–26 × 8–25 µm), single and terminal or in chains of 2–3, thin-walled, colorless; filamentous hyphae scattered, 3–6 µm wide, irregularly arranged or parallel to lamellar edge. Pileipellis 130–205 µm thick, composed of radial, thin-walled, colorless, filamentous hyphae 3–17 µm wide; vascular hyphae scarce. Volval remnants on pileus composed of vertically to subvertically arranged elements: filamentous hyphae fairly abundant to abundant, 2–8 µm wide, colorless, thin-walled, branching, anastomosing; inflated cells abundant, globose, subglobose, to ellipsoid, sometimes irregular, 23–65 × 15–55 µm, colorless, thin-walled, terminal or in chains of 2–3; vascular hyphae scarce. Volval remnants on stipe base is semblable with the structure of volval remnants on pileus, composed of irregularly arranged elements: filamentous hyphae very abundant to nearly dominant, 2–11 (–15) µm wide, colorless, thin-walled, branching, anastomosing; inflated cells fairly abundant, globose, subglobose to ellipsoid, sometimes irregular, 12–88 × 10–55 µm, colorless, thin-walled; vascular hyphae scarce. Stipe trama composed of longitudinally arranged, clavate terminal cells, 90–265 × 20–48 µm µm; filamentous hyphae abundant, 2–16 µm wide; vascular hyphae scarce. Clamps present in all parts of basidioma.
Habitat: Solitary to scattered on soil in tropical deciduous forests dominant by Dipterocarpus and Shorea. Basidioma occurs in the rainy season during May to October.
Distribution: Currently known from northern and northeastern Thailand.
Additional collections examined: Thailand, Kalasin Province: Kham Muang District, Na Bon, 16_53005” N, 103_410490 0 E, alt. 239 m, 12 August 2020, Yuan S. Liu, STO-2020-231 (SDBR-STO-2020-231); Kalasin Province: Somdet District, Mahachai, 16_480380 0 N, 103_460130 0 E, alt. 197 m, 14 August 2020, Yuan S. Liu, STO-2020-253 (SDBR-STO-2020-253); Sakon Nakhon Province: Kut Bak District, Na Mong, 17_060040 0 N, 103_540320 0 E, alt. 208 m, 15 August 2020, Yuan S. Liu, STO-2020-303 (SDBR-STO-2020-303); Chiang Mai Province: Mueang Chiang Mai District, Suthep, 18_480100 0 N, 98_570020 0 E, alt. 343 m, 26 August 2020, Yuan S. Liu, STO-2020-398 (SDBR-STO-2020-398).
Notes: Amanita kalasinensis is similar to several species that have a light yellow tinge pileus covered by pyramidal to granuliform, white volva remnants, such as A. parvipantherina Zhu L. Yang, M. Weiß & Oberw., A. sychnophyramis f. subannulata Hongo, and A. sychnophyramis Corner & Bas f. sychnopyramis. However, both A. parvipantherina and A. sychnophyramis f. subannulata differ from A. kalasinensis by having a white or brownish annulus on its stipe, as well as a darker brownish pileus. Amanita sychnophyramis f. sychnophyramis, occurring in Singapore, China, and Malaysia, is discerned from A. kalasinensis by having a larger and darker brownish pileus. Furthermore, compared with the former species, which is short of clamp and has a globose to subglobose basidiospore (6.5–8.5 × 6–8 µm, Q = 1.01 × 1.11, Qm = 1.06 × 0.03), A. kalasinensis has obvious clamps and a broadly ellipsoid to ellipsoid basidiospore (9.0–11.5 × 7.0–8.5 µm, Q = 1.25–1.53 µm, Qm = 1.40 × 0.09).
Fig 1. RAxML tree based on a combined of ITS + nrLSU + RPB2 + TEF1-a + TUB 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 and sequences from type material are marked with (T). The tree is rooted with Amanita yuaniana (HKAS58807 and HKAS68662) and A. caesareoides (HKAS92009 and HKAS92017).