Xanthagaricus necopinatus Iqbal Hosen, T.H. Li, & G.M. Gates, MycoKeys 28: 9 (2017)

Index Fungorum number: IF 822731; MycoBank number: MB 822731; Facesoffungi number: FoF 07070; Figs. 1, 2

Pileus 08–18 mm diam., convex to plano-convex, sometimes umbonate, with straight margin; covered with greyish yellow (3B5–6) crowded squamules, with brownish orange to brownish yellow (5C6–8) at center, with yellowish white (3A2) background; margin covered with greyish orange (6B4) appendiculate velar remnants, sometimes absent. Lamellae free, 2–3 mm wide, yellowish white to orange white (4A2) at first, greyish orange (5B5) when mature, ventricose to broadly ventricose, with eroded edge. Stipe 25–50×2–3 mm, cylindrical, with wider at base (4–5 mm wide), covered with greyish yellow (3B5–6) crowded squamules, with orange white (5B2) background, turning greyish red (7B5) when touched. Annulus membranous, greyish orange (6B4), fragile or absent with age. Context orange white to pale orange (5A2-3) in pileus, thin, up to 2 mm, hollow in stipe, concolorous with surface, turning greyish red (7B5) when cut. Odour and taste not observed. Spore pint orange grey (6B2). Basidiospores 4–5.5×2.5–3.7 µm, Q = 1.40–1.78, avQ = 1.64, ellipsoid to oblong-ovoid in frontal view, slightly thick-walled, smooth, hyaline to pale brown. Basidia 18–22×5–10 µm, short clavate to clavate, slightly thick-walled, hyaline, 4-spored, rarely 2-spored. Pleurocystidia absent. Cheilocystidia 15–23 × 6–12 µm, short clavate to clavate, hyaline, thick-walled. Pileus irregular epithelium, element cells oblong to short clavate, 8–23×4–17 µm, thick-walled, encrusted, with pale brown to brown parietal and intracellular pigments. Stipe covering similar to pileus covering. Clamp connections absent.

Material examined – LAOS, Oudomxay Province, Xay District, Houay Houm Village, 16 July 2014, P. Sysouphanthong, PS2014-412 (HNL502083, new record); Oudomxay Province, Beng District, Na Pa Village, 19 July 2014, P. Sysouphanthong, PS2014-463 (HNL502134).

GenBank numbers – ITS=MW040548.

Notes – Xanthagaricus necopinatus is saprotrophic on humus-rich soil and normally grows in large groups in various forest types. Xanthagaricus necopinatus is recognized by small and pale yellow to brownish yellow basidiomata, abundant appendiculate velar remnants at the pileus margin, ellipsoid to oblong-ovoid and hyaline to pale brown basidiospores, clavate cheilocystidia, and irregular epithelium of pileus and stipe covering (Figs. 1 and 2). The species was first described from Bangladesh by Hosen et al. (2017). Lao specimens resembled with the type material in terms of morphology and nrITS sequences of Lao specimens grouped with the type specimens (Fig. 3), thus confirming they are conspecific. This is the first record of Xanthagaricus necopinatus in Laos and outside of Bangladesh.

Figure 1 – Xanthagaricus necopinatus (HNL502083, new record). a, b Basidiomata

Figure 2 – Microcharacters of Xanthagaricus necopinatus (HNL502083). a Basidiospores. b Cheilocystidia. c Basidia. d Element cells at pileus covering. Scale bars: a=5 µm, b–d=10 µm

Figure 3 – Maximum likelihood phylogenetic tree of Xanthagaricus 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. Clarkeinda trachodes (HM488751) is an outgroup. Newly sequences generated from Laos is in blue