Pseudomicrothyrium X.Y. Zeng, S. Hongsanan & K.D. Hyde, gen. nov.
MycoBank number: MB 556881; Index Fungorum number: IF 556881; Facesoffungi number: FoF 06755; – 1 morphological species (this study), 1 species with molecular data.
Saprobic on dead leaves. Hyphae superficial, pale brown, septate, branched, loosely reticulate. Sexual morph: Thyriothecia superficial, circular, light brown, solitary or gregarious, slightly carbonaceous, with a colorless basal layer, connected with hyphae, easily separated from the host surface. Upper wall light brown, comprising cells of radial arrangement of textura prismatica, darken at the central ostiole, tapering at margin. Hamathecium comprising asci inclined from the base and rim towards the central ostiole, with thin, filiform, narrow cellular pseudoparaphyses. Asci 8-spored, bitunicate, fissitunicate, ovoid to obpyriform. Ascospores 2–3-seriate, fusiform to ellipsoidal, hyaline, 1-septate, upper cell slightly wider than lower cell, not constricted at the septum, with 2–4 apical appendages, usually with 2 large guttules in the upper cell, 2 small guttules in the lower cell, smooth-walled. Asexual morph: Undetermined.
Type species: Pseudomicrothyrium thailandicum X.Y. Zeng, S. Hongsanan & K.D. Hyde.
Notes: Pseudomicrothyrium is similar to Microthyrium in having hyaline ascospores with cilia around the ostiole, but differs in superficial, brown, reticulate hyphae. Phylogenetically, the new species described below forms a distinct clade within Microthyriaceae.