Annulatascus tratensis J. Yang & K.D. Hyde, sp. nov.

MycoBank number: MB 559648; Index Fungorum number: IF 559648; Facesoffungi number: FoF 12805, Fig. 56

Etymology: referring to the collecting location in Trat Province, Thailand.

Holotype: MFLU 22-0071

Saprobic on decaying wood submerged in freshwater. Asexual morph: Undetermined. Sexual morph: Ascomata solitary or gregarious, immersed to semi-immersed, lying obliquely to horizontally, perithecial, 270–550 × 240–520 μm, subglobose to ellipsoidal, dark brown, ostiolate, with a long straight neck. Ostiole periphysate. Ascomatal wall coriaceous, 28–80 μm thick, 3-layered; outer layer consisting of 3–4 rows of brown, thick-walled, polyhedral cells of textura angularis, middle layer comprising 2–3 rows of dark brown, thick-walled, elongated cells of textura angularis, inner layer comprising 6–7 rows of hyaline, thin-walled, elongated cells of textura angularis or taxtura prismatica. Paraphyses abundant, persistent, septate, hyaline, usually branched, tapering towards the apex, 3–6.7 μm wide near the base. Asci 185–230(–290) × 10.5–13.3 µm (x̅ = 220 × 11.8 µm, n = 20), cylindrical, with a long pedicel, obtuse at the apex, 8-spored, apex with a relatively massive, refractive, non-amyloid apical annulus, 3–5 µm high, 4.5–7 µm wide. Ascospores 22–32 × 7–13 µm (x̅ = 27 × 10 µm, n = 40), overlapping, uniseriate, fusiform, straight to slightly curved, hyaline, 0–3-septate, 3-septate when mature, smooth, guttulate, thin-walled, without appendages or a mucilaginous sheath.