Clarkeinda trachodes (Berk.) Singer.
Pileus 50–220 mm, first hemispherical to campanulate, expanding to convex or um-bonate, applanate to plano-concave, with straight or uplifted margin, with a large irregular patch at the center covering up to 1/3 of pileus, smooth or glabrous, light-brown (6D5–8) to brown (6E7–8), with yellowish-white or pale-yellow (4A3–4) to light-brown (6D5–8) squamules around patch toward the margin, on yellowish-white or pale-yellow (4A3–4) fibrillose background, with white velar remnants on top the central patch; margin split, with concolorous squamules same as on rest of pileus. Lamellae L = around 180, l = 1–3, 7–12 mm wide, free and remote (2.5 mm) from the stipe, white when young, becoming dull yellow (3B2) to greyish-yellow (4B2) and finally greyish-yellow (3D4) to olive (3C4), with a concolorous or white eroded edge. Stipe 80–150 10–28 mm (apex) 15–28 mm (base), wider at bulbous up to 25 mm wide base, tapering to apex, with white to yellowish-white or pale-yellow (4A3–4) surface, with concolorous squamules same as those on pileus, turning reddish-brown (8E5–7) when touched, hollow. Annulus up to 6 cm wide, attached at the upper part of the stipe, membranous, with eroded margin, fragile and ragged with age; upper side smooth or fibrillose, white to pale-yellow (4A3–4); underside covered with concolorous squamules as on pileus or stipe. Volva present, white. Context white and up to 8 mm thick in pileus with turning orange or reddish-brown (8E5–7), white and hollow in stipe with turning reddish-brown (8E5–7). Odor strong, a mixture of artificial fruit flavor and rubber. Taste not tried. Spore print greyish-yellow (3D4) to olive (3C4) or olivaceous yellow.
Basidiospores [25,1,1] 5.0–6.0 3.5–4.0 m, avl avw = 5.36 3.74 m, Q = 1.32–1.57, avQ = 1.43, ellipsoid ovoid in side-view, broadly to ellipsoid ovoid in frontal view, with trun-cate apex and germ pore, hyaline, thick-walled. Basidia 19–28 5–8 m, clavate, hyaline, thin-walled, 4-spored. Pleurocystidia absent. Cheilocystidia abundant, 20–50 12–35 m, clavate to broadly clavate, often subglobose to sphaeropedunculate with a short or long stalk, hyaline, slightly thick-walled. Pileus covering in squamules an epithelium composed of 4–5 layers of clavate or short clavate elements, often oblong to fusiform, rarely subclavate in the upper layer, 30–50 15–25 m; subglobose, oblong to clavate in the lower layer, 18–45 15–25 m; elements, with pale-brown to brown partial and intracellular pigment. Stipe covering in squamules same as those on pileus, stipe surface not observed. Clamp connections absent.
Habitat and distribution: growing solitary or in small groups, saprotrophic, on nutrient-rich soil, in the deciduous rain forest of northern Thailand.
Material examined: Thailand, Chiang Mai Province, Mae Taeng District, Pha Deng Village, alt. 900–950 m, 15 August 2011, P. Sysouphanthong, PS2011-12 (MFLU 19-2351); ibidem, 22 August 2007, P. Sysouphanthong (MFLU 09-0059); ibidem, 25 June 2007, E.C. Vellinga 3550 (UC); ibidem, 4 July 2008, E.C. Vellinga 3838 (MFLU 08-1227). Laos, Oudomxay Province, Xay District, Houay Houm Village, 16 August 2014, PS2014-752 (HNL502423).
Notes: Clarkeinda trachodes is commonly found in tropical regions of eastern and southern Asia. It has been recorded in Thailand before and Laos. This study provides a full description, line drawing, and color photos taken in the field. A new nrITS sequence data analysis showed that our new collection clustered together with specimens collected from Thailand, Bangladesh, and the type location in Sri.
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. Chlorophyllum rophyllum rachodes Vellinga is an outgroup.