Trichothyriaceae Theiss., Beih. bot. Zbl., Abt. 2 32: 3 (1914).

MycoBank number: MB 81497; Index Fungorum number: IF 81497; Facesoffungi num- bers: FoF 06893; 75 species.

Parasitic on Diatrypaceae, Meliolaceae and lichens, or on their conidial morphs. Mycelium superficial, forming thalli on hyphae of parasitized fungus, membranous. Sexual morph: Thyriothecia superficial, solitary flattened, circular, brown, with a central ostiole. Upper wall comprising radial arranged cells in parallel rows of textura epidermoidea, anastomosing at the ostiole. Basal wall well-developed, with a single-cell thick layer. Asci 8-spored, bitunicate, fissitunicate, obclavate, arranged at the periphery and converge towards the ostiole. Ascospores overlapping, hyaline or light brown, 1-septate, not constricted at the septum, sometimes with ciliate appendages. Asexual morph: Hyphomycetous. reported as Hansfordiella and Isthmospora (Hyde et al. 2011).

Type: Trichothyrium Speg.

Notes: Trichothyriaceae was introduced by Theissen (1914a) accommodating Loranthomyces, Trichothyriella, Trichothyriopsis and the type genus Trichothyrium, Hawksworth et al. (1983) included genera of Trichothyriaceae under Microthyriaceae, and this was followed by Lumbsch and Huhndorf (2010). Wu et al. (2011b) transferred them back to Trichothyriaceae based on its fungicolous life mode and a well-developed basal peridium, and included another parasitic genus Lichenopeltella in the family. This was followed by Hyde et al. (2013) and Wijayawardene et al. (2018). Trichothyriaceae differs from other thryriothecial families by a well-developed peridium, but there are too few morphological characters to delimit those similar genera. Sequence data is not available for this family.