Agaricales » Crepidotaceae » Crepidotus

Crepidotus thailandicus

Crepidotus thailandicus Phonemany, Thongkl. & Sysouph.

Faces of fungi number: FoF 150101, MycoBank: MB 850914

Basidiomata pleurotoid, small to medium. Pileus 25–50 × 15–60 mm; rounded flabelliform to reniform, convex in the attachment zone, with an incurved margin when young and going straight to reflexed when mature; white when young, turning yellowish white (4A1) to yellowish gray (4B2), brown (6D6) to light brown (6D7); surface tomentose with white hair in the primordial to young stages, disappearing when mature, the attachment zone covered with white woolly hyphae; margin white, with long translucent-striate reward to the attachment zone. Lamellar 1–2mm wide, adnate, white when young, becoming whitish to pale yellow (4A2) to brown (5D6) when fully mature, crowded, with 45 tiers of lamellulae. Stipe 1–2 × 1–1.5 mm, pseudostipe, eccentric to lateral, whitish, translucent, cylindrical. Context 1 mm wide, translucent. Odor mild. Taste none. Spore print brown (5D6).

Basidiospores [150/3/3] (4.9–)5.2–5.9–6.7(–6.9) × (4.7–)4.8–5.3–5.8(–6.2) µm, Q = (1.0–)1.05–1.11–1.22(–1.29), globose to subglobose, punctate to verrucose, buff yellow to light orange-yellow in KOH, brownish in water. Basidia (15.3–)15.3–20.7–24.9(–24.9) × (6–)6.0–7.5–8.9(–8.9) µm, clavate to subcylindric, hyaline, smooth, thin-walled 4-spored, sterigma long 2–2.5 µm long. Cheilocystidia absent. Pleurocystidia absent. Hymenophoral trama subirregular to subinverse, hyphae 4–8 µm wide, with subcylindrical to sunclavate terminal elements 48.18–104.58 × 12.45–28.72 µm, hyaline. Pileipellis a cutis, composed of parallel hyphae 4–8 µm wide, branched, hyaline, with cylindrical terminal elements 54.6–91.34 × 9.15–14.08 µm. Oleiferous hyphae 2–4 µm present in the hymenophoral trama and pileipellis. Clamp connections are present in all structures.

Habitat and distribution: Saprobic on dead branches, scattered, or gregarious with at least 3–8 basidiomata. This has only been found in northern Thailand.

Additional specimens examined: — THAILAND, Chiang Rai Province, Mae Fah Luang District, Mae Sa Long Nok Subdistrict, 20°10'10.9"N, 99°37'21.5"E, 10 June 2019, Monthien Phonemany (MFLU23-0424), Chiang Mai Province, Mae on District, Pox Kaew Village, 18°52'1"N, 99°19'29"E 24 June 2019, Monthien Phonemany (MFLU23-0426).

Notes: Crepidotus thailandicus is characterised by a rounded flabelliform, tomentose surface with white hair when primordial to young stages then disappearing when old, when mature present long transtucent-striate reward to the point of attachment that becomes fade away at the central, punctate to verrucose basidiospores, with cheilocystidia absent and pleurocystidia absent. According to morphology comparisons do not detect a species description for C. thailandicus that exactly fits any of the literature currently available (Bandala et al. 2008; Dennis 1974; Ge & Bau 2020; Hausknecht & Krisai-Greilhuber 2010; Hesler & Smith 1965; Jančovičová et al. 2022; Kim et al. 2021; Kumar et al. 2022; Kumar et al. 2018, 2020; Senn-Irlet 1995). The most similar species were C. globisporus A.M.Kumar & C.K.Pradeep, but smaller basidomata (3–35 mm), surface fibrillose, vesiculose clavate cheilocystidia are present for C. globisporus (Kumar et al. 2020).

The phylogenic tree showed that C. roseocarpus (MFLU23-0435, MFLU23-0437) was closely related to C. thailandicus (MFLU23-0425) with high bootstrap support (Figure 1). However, they are totally different in morphological characteristics, which C. roseocarpus has larger basidiomata and pastel pink, larger basidiospores (5.3–11.3 × 4.48–6.63 µm), larger basidia (13.9–21.6 × 5.1–7.4 µm), and the presence of hymenophoral trama in convergent form (this study).