Crepidotus flavocarpus Phonemany, Thongkl. & Sysouph.

Phonemany, Monthien, Sysouphanthong, Phonguen & Thongklang, Naritsada, 2024, Additions to Crepidotus species (Basidiomycota): Six new species and two new records from Thailand, Phytotaxa 646 (2), pp. 91-115 : 99-100

Crepidotus flavocarpus Phonemany, Thongkl. & Sysouph. , sp. nov. ( Figures 4–5 )

Faces of fungi number: FoF 15097, MycoBank: MB 850911

Etymology:— Flavus refers to yellow, and carpus refers to the body; flavocarpus refers to the yellow basidiomata of the holotype.

Holotype:— THAILAND. Chiang Mai Province, Mae on District, the mountain behind Thangthong lodges, 18°52’04.5”N, 99°18’26.5”E, 25 June 2020, Monthien Phonemany ( MFLU23-0427 ).

Diagnosis:—This species is characterized by small yellow basidiomata, velutinous pileus, densely white near the attachment zone and sparse toward the margin, brown basidiospores, various shapes of cheilocystidia, with utriform to cylindrical with sub-capitate at the apex, inverse hymenophoral trama, and cutis pileipellis.

Description: Basidiomata pleurotoid, small. Pileus 10–30 × 9–25 mm; ungulate to spathuliform when primordial stages, becoming petaloid to rounded flabelliform expanding to dimidiate, sometimes convex, plano-convex when mature, with an incurved margin when young and becoming straight when mature; yellow to yellowish, light yellow, pastel yellow, pale yellow becoming yellowish white then brownish grey to greyish brown when old (3B7–8, 3A2–5, 5D2–3); covered with densely velutinous at the point of attachment, with white hairs in the attachment zone and sparse toward the margin, disappearing when old, hygrophanous; margin with short striate or sulcate, concolorous with surface to paler yellow at first, then white to brownish when old. Lamellae 2–3 mm wide, adnexed to sinuate, pale yellow, pastel yellow to white (3A2–3, 3A1), becoming dark brown spots on the surface of the lamellae when mature, distant, with 3–4 tiers of lamellulae, with smooth edge. Stipe absent. Context very thin, white to translucent when old. Odor and taste indistinct, mild. Spores print brown (6D 6, 6E 6).

Basidiospores [150/3/3] (5.5–)5.6–6.8.–7.6(–7.8) × (4.1–)4.3–5.5–6.5(–6.6) µm, Q = (1.01–)1.03–1.25–1.47(–1.53), globose to subglobose, yellowish brown (5D5–6), smooth, thick-walled. Basidia (14.8)14.8–18.7–21.2(–21.2) × (5–)5–6.9–8.1(–8.2) µm, subclavate, 4-spored, hyaline, smooth, thin-walled. Cheilocystidia (18.3)18.9–34.2–52.1(–55.9) × (4.1–)4.1–5.2–7.4(–7.8) µm, subcylindrical, narrowly utriform to sublecythiform, with subcapitate at apex, hyaline, smooth, thin-walled. Pleurocystidia absent. Hymenophoral trama inverse, hyphae 3–5 µm, with cylindrical terminal elements (17.1)18.8–25.1–30.6(–31.1) × (4.3–)4.4–5.5–6.7(–6.8) µm, hyaline, thin-walled. Pileipellis a cutis, hyaline to pale yellow, with cylindrical terminal elements 35–80 × 4–8 µm. Clamp connections present in pileipellis and hymenophoral trama.

Habitat and distribution:—Saprobic on dead wood, scattered by 2–3 basidiomata. So far, this has only been found in tropical forests in northern Thailand.

Additional specimens examined:— THAILAND, Chiang Mai Province, Mae on District, Huai Kaeo Subdistrict, 18°52’04.0”N, 99°18’27.8”E, 25 June 2020, Monthien Phonemany (MFLU23-0428).

Figures

FIGURE 4. Basidiomata of Crepidotus flavocarpus in the field. a–d MFLU23-0427, e–f MFLU23-0428. Scale bars a–f 1 cm.

FIGURE 5. Micromorphology of Crepidotus flavocarpus, a Basidiospores, b Basidia and basidoles, c Cheilocystidia, and d Pileipellis. Scale bars: a = 5 µm, b 10 µm, c = 20 µm, d = 50 µm.