Chlorophyllum molybdites

Chlorophyllum molybdites (G. Mey.) Massee, Kew Bull

Index Fungorumnumber: IF 604726; Facesoffungi number: FoF 03445

Pileus 70–110 mm, globose to subglobose when young, expanding to convex, plano– convex, with low umbo, with straight margin, with glabrous calotte at center, light-brown to brown (7D5–6), with concolorous patches and squamules scattered toward margin, on concentrically fibrillose background, orange-white (6A2) around umbo, and white around marginal zone; margin fibrillose, fringed, exceeding lamellae when mature. Lamellae free, broad, crowded, white when young, becoming dull green (27D3) when mature, with an eroded edge. Stipe 60–85 × 10–12 mm, widening downward base, 18–23 mm at the base, white to yellowish-white (4A2), smooth, hollow. Annulus free, descending, with a cuff around stipe, movable, white; underside concolorous with umbo. The context in pileus and stipe white, turning brownish-orange (7C5). Smell carrot-like. Taste not observed. Spore print grayish-green (27C3–4).

Basidiospores [100,5,5] 8.5–13 6–7.5 m, avl avw = 9.6 7.0 m, Q = 1.3–1.5, avQ = 1.4, ellipsoid-amygdaliform, with truncate apex and germ pore, hyaline or pale-green, thick-walled, dextrinoid, congophilous, cyanophilous, and metachromatic in Cresyl blue. Basidia 29–36 10–12 m, 4-spored, some 1-spored or 2-spored, hyaline, slightly thick-walled. Lamella edge sterile. Cheilocystidia 14–35 10–20 m, clavate, broadly clavate, hyaline, slightly thick-walled. Pileus covering a hymeniderm made up of tightly packed clavate, narrowly clavate, oblong, cylindrical, elements; terminal elements 25– 62.5 5.0–12 m, with hyaline to pale-brown parietal pigment. Stipe covering a cutis made up of cylindrical to narrowly cylindrical elements, 4.5–7.5 m wide, thin-walled, hyaline. Clamp connections not found.

Habitat and distribution: growing in small groups to large groups or fairy rings in grasslands and under shade trees along with grasslands, saprotrophic and terrestrial, throughout northern Thailand.

Material examined: Thailand, Chiang Rai Province, Muang District, Mae Fah Luang University Campus, 7 May 2009, P. Sysouphanthong and J-K. Liu, BJP0041; ibidem, 22 July 2012, P. Sysouphanthong, 2012-9 (MFLU 12-1772); ibidem, 05 August 2012, P. Sysouphan-thong, 2012-12 (MFLU 12-1775); Chiang Rai Province, Muang District, Pongphrabath Village, 17 July 2012, P. Sysouphanthong, 2012-2 (MFLU 12-1765); Pha Yao Province, Muang District, Kuawn Pra Yuan Area, 12 June 2011, P. Callac and S.C. Karunarathna, 2011-11 (MFLU 12-1819).

Notes: Chlorophyllum molybdites are easy to recognize by the free and dull green lamellae when fully mature, the grayish-green spore print, and the large basidiomata with a light-pileus with brown squamules at the center. All parts of the basidioma turn orange to red when damaged. It is often found in lawns and grasslands. The species might be confused with Macrolepiota species when samples are collected in a young stage. It could also be confused with Clarkeinda trachodes (Berk.) Sing, which has a yellow to olive-brown spore print, a much flimsier annulus, and white velar remnants over the pileus scales. Cl. trachodes grows in northern Thailand in the same area and habitat as C. molybdites, but has not been found outside Asia yet. For differences with C. globosum, see notes under that species. Chlorophyllum molybdites is widespread, especially in subtropical and tropical re-gions. In northern-temperate regions in Europe, it was found only in-doors, Watling. It was first recorded in Thailand by Høiland and Schumacher (1982), and since then, there have been several reports of the species throughout Thai-land. However, those studies were only based on their macro-morphological characters. This is the first study on C. molybdites in Thailand, providing a full description and illustrations. Læssøe et al. recorded this species from Xiangkhouang Province of northern Laos. In the nrITS sequence analysis (Figure 1) and in the combined nrITS-rnLSU-rpb2 analysis (Figure 1), three sequences of Thai specimens from this study are clustered with other specimens from other countries worldwide. Chlorophyllum molybdites cause gastrointestinal distress, but the severity of the reactions to this species differs among people and whether the mushrooms have been cooked or not. The list of synonyms as given above is based on morphology; it is possible that some of the names, such as Agaricus congolensis Beeli, in fact, refer to C. globosum, which is morphologically very similar to C. molybdites.