Effusomyces thailandicus

Effusomyces thailandicus Yue Li, Nakasone & S.H. He 2022, in Li, et al., Journal of Fungi, 8, 1229 (2022)

Etymology: refers to Thailand, the type locality.

Diagnosis: Basidiomes annual, resupinate, widely effused, adnate, inseparable from substrate, membranaceous, first as small patches, later confluent up to 12 cm long, 3 cm wide, up to 20 µm thick in section. Hymenophore smooth, pale yellow (4A3) or greyish yellow (4B3), unchanged in KOH, without cracks; margin thinning out, adnate, indistinct, concolorous with hymenophore surface. Context cream-colored.

Microscopic structures—Hyphal system monomitic; generative hyphae bearing clamp connections. Subiculum thin, sparse, dense tissue with hyphae arranged more or less parallel to substrate; hyphae slightly thick-walled, colorless, smooth, infrequently branched, moderately septate, 2.5–3 µm in diameter Subhymenium indistinct, a sparsely interwoven tissue; hyphae thin-walled, colorless, smooth, infrequently branched, moderately septate, 1–2 µm in diameter Hyphidia rare, simple, filamentous or with lateral or apical bumps or knobs, thin-walled, colorless, smooth, 17–31 × 1.5–2 µm. Cystidia or gloeocystidia absent. Basidia clavate to subcylindrical, usually with a slight medial constriction, thin-walled, colorless, smooth, with four sterigmata and a basal clamp connection, 10–26 × 3–6 µm. Basidiospores ellipsoid, with tiny apiculus, thin-walled, colorless, smooth, IKI–, CB–, 5–6.5 × 3–4.2 (–4.9) µm, L = 5.9 µm, W = 3.8 µm, Q = 1.5–1.6 (n = 90/3).

Index Fungorum Number: IF844195

Notes: Except for the small basidia producing relatively large basidiospores and very thin basidiomes, there are no outstanding morphological features of E. thailandicus. The hyphidia are easily overlooked, for they are inconspicuous and scarce.