Neohelicascus griseoflavus J. Yang & K.D. Hyde, sp. nov.

MycoBank number: MB 559602; Index Fungorum number: IF 559602; Facesoffungi number: FoF 12791;

Etymology: grisei = gray, flavus = yellow, referring to the grayish yellow ascospores.

Holotype: MFLU 22-0059

Saprobic on submerged decaying wood. Asexual morph: Undetermined. Sexual morph: Ascomata scattered or gregarious, immersed, perithecial, 280–400 μm high, 250–380 μm diam., subglobose or obovoid, brown, ostiolate, with conidial masses at the apex of the immersed short neck. Ostioles periphysate. Ascomatal wall coriaceous, undifferentiated from host tissue, 20–50 μm thick, consisting of multi-layered cells of textura angularis, outer layers with brown, polygonal, thick-walled cells, inner layers with pale brown to hyaline, polygonal to elongated, thin-walled cells. Hamathecium composed of 1.2–2.4 µm wide, filiform, hyaline, septate pseudoparaphyses. Asci (120–)150–200(–215) × (15–)19–22(–24) µm (x̅ = 170 × 20 µm, n = 20), bitunicate, fissitunicate, clavate, rounded at the apex with an ocular chamber, 8-spored, pedicellate, with a long tail-like extension. Ascospores 24–31 × 8.5–11 µm (x̅ = 28 × 10 µm, n = 30), overlapping, obliquely 1–2-seriate, lunate to fusiform, grayish yellow when young, becoming pale brown when mature, uniseptate, smooth-walled, guttulate, slightly constricted at the septum, apical cell usually slightly broader and shorter than the basal cell.