Chlorophyllum globosum

Chlorophyllum globosum (Mossebo) Vellinga

Index Fungorumnumber: IF 374394; Facesoffungi number: FoF 07069

Pileus 50–200 mm, subglobose to globose when young, expanding to parabolic to con-vex, plano-concave when fully mature, with straight or slightly inflexed margin; glabrous at the center, pale-orange to brownish-orange (5A2–3, 6C7–8), with concolorous patches of irregular shapes around the center and scatted towards the margin and fragile when mature, on white to yellowish-white (2A2, 3A2, 4A2) felted or fibrillose background and turning pastel red to red (9A4–6) when touched; margin white, sulcate, but non-striate, not fringed, exceeding lamellae when mature. Lamellae free, slightly remote from the stipe, white to orange-white (5A1–2) when young, turning pastel red to red (9A4–6) when touched, pastel green to grayish-green (29A4, 29B4) when fully mature, crowded, ven-tricose, and narrowly to pileal margin, up to 20 mm wide, with the eroded edge. Stipe 85–210 12–31 mm, tapering to apex, with bulb-like, 30–34 mm wide base; white to brownish-orange (6C3–6) background, sometimes with some white fibrils at apical zone, turning pastel red to red (9A4–6) when touched, with white rhizomorphs connected to the substrate. Annulus under-developed, cuff-like, moveable when mature, white and fibrillose in the upper part, at underside with squamules similar to the patches on the pileus. Context thick and white in pileus, white in the stipe, brownish-orange (6C3–6) at apical zone, paler in the middle zone, and white toward the base, turning pastel red to red (9A4–6) in both pileus and stipe context. Smell and taste not observed. Spore print dull green to grayish-green (29D3–5, 29D5–6).

Basidiospores [75,3,2] 9.0–12.0 × 7.0–9.0 µm, avl × avw = 10.3–11.3 × 7.4–8.3 µm, Q = 1.3–1.57, avQ = 1.4, in side-view broadly ellipsoid to ellipsoid-amygdaliform, in frontal view broadly ellipsoid or amygdaliform, with truncate apex and germ pore, thick-walled, hyaline to hyaline green, dextrinoid, congophilous, cyanophilous, metachromatic. Basidia 22.0–34.0 × 9.0–14.0 µm, clavate, hyaline, thin-walled, 4-spored, often 2-spored, rarely 1-spored. Lamella edge sterile. Cheilocystidia 30.0–58.0 × 10.0–29.0 µm, essentially clavate, occasionally with a slightly long stalk, rarely utriform and spheropedunculate, thin-walled and colorless. Pleurocystidia absent. Pileus covering a hymenoderm made up of layers of oblong to cylindrical, narrowly clavate elements, terminal elements 40.0–100 × 5.0–11.0 µm, with rounded or attenuate apex, hyaline and thin-walled, sometimes with pale-yellow intracellular pigment in upper elements. Clamp connections not found.

Habitat and distribution: growing in small groups, saprotrophic, on nutrient-rich soil, in grassland in shade of Samanea saman and on soil rich in humus in deciduous rain forest during June to August in the wet season of northern Thailand and also known from Vientiane Capital, Laos.

Material examined: THAILAND, Chiang Mai Province, Mae Taeng District, Pongduad Village:16 06016.100 N; 99 43007.900 E, alt., 780–805 m, 16 June 2010, P. Sysouphanthong, P37 (MFLU 10-0555); Chiang Rai Province, Muang District, Ratjabhat University Campus, 30 August 2012, P. Sysouphanthong, 2012-21 (MFLU 12-1815); Chiang Rai Province, Muang District, Forest of Mae Fah Luang University Campus, 10 July 2019, P. Sysouphanthong, 2019-24 (MFLU 19-2357). LAOS, Vientiane Capital, Xaythany, Houay Yang Preserve Forest, 16 June 2017, P. Sysouphanthong, PS2017–7 (HNL503445).

Notes: Chlorophyllum globosum is recognized by medium to large-sized, white basidiomata, subglobose to globose pileus, which expands to convex when mature, pale-brown to orange-brown patches on white pileus, a white stipe, a cuff-like annulus, and a reddening reaction in most parts of the basidioma when touched or damaged. Chlorophyllum globosum was described from Cameroon as Macrolepiota globosa, and the Thai material fits the description very well, except for the spore color, which was originally given as white. The species was transferred to Chlorophyllum by Vellinga, based on phylogenetic analyses of ITS and LSU. C. globosum is very close to C. molybdites in morphology, and they are sister taxa in the phylogenetic trees, but they are definitely different species The noticeable differences between the Chlorophyllum molybdites and C. globosum samples from Thailand and Laos are the whiter basidiomata, longer elements of the pileus covering, and longer cheilocystidia with a distinct stalk in C. globosum, while cheilocystidia are subglobose, broadly clavate to clavate without a long stalk in C. molybdites. However, they are identical in most other characteristics. If we had not obtained sequence data from our collections, this species would most probably not have been recognized, and the different morphology of the cheilocystidia tabled as an intraspecific variation. Chlorophyllum globosum is now known from various countries in Africa (Benin, Cameroon, and South Africa) and Asia (India, Laos, Thailand, and China). The occurrence in some countries is based on ITS sequences in GenBank that are identical to those from Thailand.

Fig 1. Maximum Likelihood tree of Chlorophyllum based on analysis of nrITS-LSU-rpb2 sequence data. Bootstrap values (ML/B) are given above the branches. Bootstrap values for maximum likelihood equal to or greater than >60 and Bayesian posterior probabilities >0.95 are placed above the branches. Abbreviations are as follows: A. = Agaricus, C = Chlorophyllum, and Cl = Clarkeinda. Clarkeinda trachodes and Agaricus campestris are used as outgroup. New sequences are in bold type.