Lasiolepiota thailandica Wisitrassameewong, Sysouph. & Vellinga 2026, sp. nov.

Lasiolepiota thailandica Wisitrassameewong, Sysouph. & Vellinga sp. nov. Figs 4, 5 Etymology. “ thailandica ” from the country of the holotype “ Thailand ”. Holotype. Thailand • Nakhon Nayok Province, Khao Yai National Park, 03 August 2022, collected by Komsit Wisitrassameewong (BBH 49568, holotype). Description. Basidiomata medium to large-sized. Pileus up to 115 mm diam., convex, expanding to umbonate to plano-concave, with straight to deflexed margin; with an irregular patch at center or umbo, glabrous, persistent, reddish white (9 A 2–3) to reddish gray to dull red (9 B 2–3), around patch covered with a thick layer of fibrous felt or woolly floccules towards the margin, crowded, reddish gray to dull red (8 B 2–3) to brownish gray (8 C 2–3), darker when wet, reddish brown (8 D 4–6), on white background; margin felted, with velar remnants or appendiculate, reddish gray (8 B 2). Lamellae free, remote from the stipe, white, very crowded, broadly ventricose, up to 5 mm wide, with up to 3 series of lamellulae, with concolorous eroded lamella edge, turning reddish white to pale red (8 A 2–3) when touched. Stipe 85–110 × 6–10 mm, cylindrical or slightly wider towards base, with white background at the top to the annulus zone, below the annulus covered with a layer of fibrous felt or woolly floccules as on pileus, reddish gray to dull red (8 B 2–3) from apex to annular zone, brownish gray (8 C 2–3) to reddish brown (8 D 4–6) from annular zone down towards base, with white fibrous rhizomorphs. Annulus hanging down, white on the upper side and covered with concolorous fibrous felt as on the stipe surface at underside, sometimes fragile or disappearing when mature. Context white and thick in pileus, up to 10 mm thick, turning reddish white to pale red (8 A 2–3) when cut or darker when dry, in stipe white, hollow, turning color as in pileus, dull white with age. Taste and odor not observed. Spore print white. Basidiospores [50 / 1 / 1] l × w = 4.5–5.0 × 3.2–3.8 μm, al × aw = 4.904 × 3.41 μm, Q = 1.26–1.66, Qav = 1.44, ellipsoid ovoid to amygdaliform in side view, in frontal view ellipsoid, smooth, hyaline, slightly thick-walled, dextrinoid, congophilous, cyanophilous in cotton blue, not metachromatic in Cresyl blue. Basidia (n = 20) 15–20 × 7.5–10 μm, short clavate, hyaline, 4 - spored. Lamella trama regular to slightly irregular. Pleurocystidia absent. Cheilocystidia (n = 20) 15–25 × 7–10 μm, short clavate to clavate, sometimes fusiform or utriform, rarely oblong, hyaline, sometimes branched. Pileus covering complex, made up of irregular and branched hyphae, cylindrical and interwoven; hyphae (n = 15) 8–20 μm wide; terminal elements (n = 20) 80–125 × 10–18 μm, cylindrical sometimes with incrusting, often with brown parietal and intracellular pigment. Stipe covering similar to pileus covering. Clamp connections absent. Additional material examined. Thailand • Chiang Mai province, Mae Taeng district, Pha Deng village, 25 June 2007, collected by Else C. Vellinga (ecv 3556, UC)). Habitat and distribution. On humus-rich soil of deciduous forest dominated by species of Fagaceae. One collection was found in Khao Yai National Park, Nakhon Nayok Province of central Thailand, and one collection was found in Chiang Mai Province, northern Thailand. Note. Lasiolepiota thailandica has a distinct glabrous patch on the pileus and a broad pileus up to 115 mm. Lasiolepiota thailandica shares its morphology with La. oinochroa, but has much larger basidiomata, lighter colored patch (reddish white to reddish gray), a lighter colored layer of fibrous felt or woolly floccules (reddish gray to brownish gray) on pileus and stipe, and turning reddish white to pale red while not discoloring in La. Oinochroa when cut. However, their microcharacters are very similar (Figs 2, 3, 4, 5). Moreover, they clustered in the phylogenetic analysis with high BS (100 %) (Fig. 1). Mystagaricus brunneolilacinus differs from La. thailandica by its smaller basidiomata, absence of a glabrous patch at the center of the pileus, and purplish brown to vinaceous pileus- and stipe covering (Radnóti et al. 2025).