Crepidotus viscidus

Crepidotus viscidus Phonemany, Thongkl. & Sysouph

Faces of fungi number: FoF 150103, MycoBank: MB 850915

Basidiomata pleurotoid, small. Pileus 10–18 × 5–12 mm; semicircular, spathuliform, with incurved to straight margin; white (3A1) to pastel yellow (3A4); smooth, slightly viscid, not hygrophanus, the attachment zone covered by white woolly hyphae; margin zone, gray (1E1) to dark gray (1F1), with translucent-striate. Lamellae 1 mm wide, when young, white, becoming pale orange (5A2) to orange white (5A1), finally light brown with age (5D8). Stipe absent or pseudostipe. Context 1 mm wide, white, glutinous. Odor and taste none. Spore print brownish (6D8) to brown (6E8).

Basidiospores [150/3/3] (5–)5.4–6.3–7.4(–7.8) × (3.9–)4.2–4.8–5.4(–5.9) µm, Q = (1.04–)1.11–1.32–1.51(–1.54), globose to subglobose, ellipsoid in side view, smooth, yellow to light orange-yellow in KOH, brown in water, thin, thick-walled. Basidia (15.5)15.5–19.8–25.3(–25.3) × (5.8–)5.8–6.7–7.7(–7.7) µm, subclavate, 4-spored, sterigmata 3–5 µm long, hyaline, smooth, thin-walled. Cheilocystidia (13.5–)13.5–22.1–32.7(–32.7) × (5.6–)5.6–8.4–11.2(–11.6) µm, subcylindrical, narrowly utriform to utriform, fusiform to broadly fusiform, lecythiform to sublecythiform, with subcapitate at apex, hyaline, smooth, thin-walled. Pleurocystidia absent. Hymenophoral trama regular to subregular, hyphae 2–4 µm wide, hyaline. Pileipellis a cutis, composed of parallel hyphae 4–8 µm wide, branched, hyaline, with cylindrical terminal elements 56–90 × 5–7 µm. Oleiferous hyphae 2–4 µm present in hymenophoral trama. Clamp connections are present in all structures. 

Habitat and distribution: — Saprobic on dead wood, scattered or fasciculate by 4–10 basidiomata. This has been only found in northeast Thailand and northern Thailand.

Additional specimens examined: — THAILAND, Chiang Mai Province, Mae on District, Pox Kaew Village, 18°52'1"N, 99°19'29" E, 25 June 2019, Monthien phonemany (MFLU23-0431). Roi Et Province, Mayyadee District, Somsaart Subdistrict, 16°25'49.7"N, 103°51'26.2"E, 18 August 2020, Monthien Phonemany (MFLU23-0433), (MFLU23-0434).

Notes: — Crepidotus viscidus is characterised by semicircular white pileus, margin zone grey to dark grey, lamellae pale orange to orange white, smooth basidiospore, narrowly utriform to utriform, fusiform to broadly fusiform, lecythiform to sublecythiform shape of cheilocystidia. In the phylogenetic study, the clustering of C. viscidus (MFLU23-0432) observed within the clade seven included closely related species are C. alabamensis (TBGT15610), C. albolanatus (PDD 72865), C. aureus (OKM27300), C. eucalyptorum (G1749), C. flavocarpus, C. roseus (TBGT15507), C. tigrensis (B2200). However, the species mentioned have different morphological characteristics; C. alabamensis described in India differs by having a lager basidiomata (2–3 mm), pastel yellow pileus, smaller basidia (19–22 × 6.5 µm), and pileipellis an ixocutis(Kumar et al. 2022). Crepidotus albolanatus differs in having a pure white pileus, plano-convex to applanate shape of the basidiomata, with larger basidiomata (5–40 × 5–50 mm), stipe cylindrical whitish, with pubescent, larger basidia (13–19.4 × 5–6.6 µm), and larger cheilocystidia (28.8–40.9 × 8.1–11.9 µm) (Horak 2018; Jančovičová et al. 2022). Crepidotus eucalyptorum described from Australia differs in having matt to fibro-villous or fibrillosely scaly, basidiospores (7.2–10 × 5–6.6 µm). Crepidotus flavocarpus described in Thailand differs in that it has yellow to yellowish pileus basidiomata, the margin is discolorous and pale yellow (This study). Crepidotus roseus described in Turkey differs in that it has scarlet to cinnabarred, velvety-tomentose, verruculose basidiospores (7–8 × 5–6 µm), with thin walls (Güngör et al. 2014).