Macrolepiota detersa Z. W. Ge, Zhu. L. Yang and Vellinga.
Index Fungorum number: IF 518349; Facesoffungi number: FoF 09698.
Pileus 60–160 mm, when young globose to subglobose, expanding to convex, umbon-ate, broadly campanulate, plane-umbonate, with straight or decurrent margin; when young glabrous, brownish-orange to light-brown or dark red-brown (7C5–6, 8–9 F7–8), surface-breaking around the center, with concolorous squamules or patches around glabrous calotte at the center toward the margin, crowded, with distantly fragile patches toward margin), with concolorous brownish-orange (7C5–6) fibrillose squamules or squamules between patches towards the margin, on white to yellowish-white (4A2) matted-fibrillose to the felted background; margin splitted, covered with light-grey (6C3) to grey orange (6B3) granular-floccose Universal Veil elements. Lamellae free, slightly remote from the stipe, white, sometimes with reddish spots, ventricose to broad, 8–16 mm wide, close to crowded, with the eroded edge. Stipe 80–400 12–18 mm, cylindrical with slight wider downward base, with bulb at base, 20–30 mm; dull, dry, scurfy to squamulose overall, minute squa-mules at apex zone to middle and squamules downward base, concolorous with those squamules on pileus, on brown-grey (6C3) background. Annulus superior, membranous, thin, descending, double, persistent but easily removable, pendulous, 30–40 mm long, with concolorous squamules underside of internal cuff-liked. Context white and thick in pileus; stipe white and hollow, fibrous, turning pinkish-grey when cut, not changing color in bulb. Taste not observed. Smell strong, pleasant. Spore print white.
Basidiospores [50,2,2] 14–16.2 9.5–11 m, avl avw = 15.2 10.1 m, Q = 1.45–1.62, avQ = 1.52, ellipsoid amygdaliform, ellipsoid to oblong in frontal view, with apical germ pore and hyaline cap, hyaline and thick-walled, dextrinoid, congophilous, cyanophilous, metachromatic in Cresyl Blue. Basidia 38–41 12–14 m, clavate, slightly thick-walled, hyaline, 4-spored. Lamella edge sterile. Cheilocystidia 20–25 7–14 m, short clavate to clavate, irregular clavate, rarely utriform, sometime branched, hyaline, thin-walled. Pleuro-cystidia absent. Pileus covering a hymenoderm made up of layers of oblong to cylindrical elements, branched, terminal cylindrical elements cylindrical or fusiform, oblong, with rounded or attenuate to apex, 10–80 7–16 m, slightly thick-walled, with hyaline to pale-brown parietal pigment. Stipe covering not observed. Clamp-connections not found.
Habitat and distribution: solitary, saprotrophic, and terrestrial, growing on the ground beside a grassland or yard, and ground with decomposing deciduous leaves from the mixed rain forest, dominant species being Castanopsis spp. in northern Thailand and in northern Laos. This is proposed as a new record for tropical Southeast Asia.
Material examined: Thailand, Chiang Rai, Muang District, Pong Phra Bath Village, 8 June 2011, P. Sysouphanthong, 2011-10 (MFLU 12-1772); Chiang Rai, Mae Fah Luang District, Mae Sa Long Nok Village, 9 July 2012, P. Sysouphanthong, 20112-19 (MFLU 12-1784). Laos, Oudomxay Province, Xay District, Houay Houm Village, 28 July 2014, P. Sysouphanthong, PS2014-567 (HNL502238).
Notes: Macrolepiota detersa is recognized by medium to large and very tall basidiomata, white to yellowish-white pileus covering with brownish-orange to light-brown central calotte and patches or squamules, white and free lamellae, long stipe with a draping white membranous annulus attached at the upper part, amygdaliform basidiospores with germ pore and hyaline cap, clavate to narrowly clavate cheilocystidia, and the hymenidermal pileus covering made up of oblong to cylindrical elements.
Macrolepiota detersa was originally described, from a temperate region in the Anhui province of eastern China, as an edible species by Ge et al. It was already known from Japan (as an undescribed species; Vellinga et al. and was later reported from South Korea. Here we record its presence in northern Thailand and Laos.The ITS sequence of the Thai collection is identical to materials from China, Japan, and South Korea with 100% bootstrap support, and it is sister to M. excelsa.
Fig. 1 Maximum likelihood phylogenetic tree of the Agaricus clade in the Agaricaceae based on nrITS-LSU sequence data. New sequences generated from Thailand are in bold. Bootstrap values (ML/B) are given above the branches. Boot-New sequences generated from Thailand are in bold. Bootstrap values (ML/B) are given above the branches. Bootstrap strap values for maximum likelihood equal to or greater than ≥60 and Bayesian posterior probabilities ≥ 0.95 are placed values for maximum likelihood equal to or greater than 60 and Bayesian posterior probabilities 0.95 are placed above the above the branches. Genus abbreviations are as follows: A = Agaricus, C = Chlorophyllum, Cl = Clarkeinda, Co = Coniolepiota, E = Eriocybe, E = Eriocybe, H = Heinemannomyces, Ha = Hymenagaricus, Ps = Pseudolepiota, M = Micropsalliota, and X = Xanthagaricus. Chlorophyllumrophyllum rachodes Vellinga is an outgroup.