Chlorophyllum hortense (Murrill) Vellinga, Mycotaxon 83: 416 (2002)

Index Fungorum number: IF 374396; MycoBank number: MB 374396; Facesoffungi number: FoF 03444; Figs. 1, 2

Pileus 72–98 mm, convex, expanding to umbonate with distinctly umbo, with straight margin, surface covered with light brown to yellow brown (5D4–5) glabrous calotte at center, with brownish yellow (5C7–8) irregular patches or squamules toward margin, on orang white to light orange (5A2–4) background, margin sulcate or slightly striate, white. Lamellae free, narrowly fusiform, up to 7 mm wide, white, crowded, lamella-edge eroded. Stipe 60–110×6–7 mm, cylindrical, slightly wider to base; surface smooth, white. Annulus superonate, moveable, white, with brownish yellow (5C7–8) on upper part. Context white in pileus, white in stipe and hollow. All parts of basidiomata turning orange-white (5A2) when touched. Taste peanutlike. Smell mild. Spore print white. Basidiospores [50,2,1] 6–8.5×5–6.5 µm, avl×avw=7.5×6 µm, Q=1–1.5, Qav=1, in side-view broadly ellipsoid to ellipsoid amygdaliform, in frontal view ellipsoid, oblong, without germ pore, hyaline, dextrinoid, congophilous, cyanophilous, metachromatic. Basidia 25–30 × 8–11.5 µm, clavate, hyaline, 2-spored, occasionally 1-spored. Lamella edge sterile, with abundant cheilocystidia. Cheilocystidia 35–50 × 7–9 µm, narrowly clavate, cylindrical, sometimes with short apical excrescence or appendage, colorless. Pleurocystidia absent. Pileus covering of scales a trichoderm made up of cylindrical, narrowly clavate elements with long stalk, 30–155×6–16 µm, colorless or with pale brown parietal pigment, with encrusted wall in some elements and lower hyphae. Stipe covering a cutis made up of cylindrical hyphae and elements, colorless, 10 µm wide. Clamp connections not observed.

Material examined – LAOS, Oudomxay Province, Xay District, Houay Houm Village, 19 July 2014, P. Sysouphanthong, PS2014-478 (HNL502149, new record).

GenBank numbers – ITS=MW040573.

Notes – Two basidiomata of Chlorophyllum hortense were found in grasslands in Laos. Chlorophyllum hortense is characterized by white to yellowish brown pileus, free and white lamellae, and the presence of annulus (Fig. 1). Microcharacters are oblong ovoid and white basidiospores without a germ pore, basically 2-spored basidia, clavate to cylindrical cheilocystidia, trichodermal pileus covering made up of narrowly clavate elements, without clamp-connection in all tissue (Fig. 2). Chlorophyllum hortense is distributed amongst tropical countries, mostly found on grassland, dung or compost (Vellinga 2004). This species is similar to C. demangei except that the latter has 4-spored basidia. Phylogenetic tree confirmed that they are different species (Fig. 3).

Figure 1 – Chlorophyllum hortense (HNL502149, new record). a, b Basidiomata

Figure 2 – Microcharacters of Chlorophyllum hortense (HNL502149). a Basidiospores. b Basidia. c Cheilocystidia. d Element cells at pilus covering. Scale bars: a–c=10 µm, d=20 µm

Figure 3 – Maximum likelihood phylogenetic tree of Chlorophyllum based on nrITS sequences. The maximum likelihood (ML) analysis was performed in RAxML 7.2.6 (Stamatakis et al. 2008) and maximum parsimony (MP) analysis was performed the program PAUP* 4.0 b10 (Swofford 2004). Bootstrap values of ML/MP equal to or greater than 70% are given above branches. GenBank accession number is indicated after species name. Agaricus bisporus (FJ223228) is an outgroup. The three shows six different sections. Newly sequences generated from Laos are in blue