Chaetothyrium Speg., Anal. Soc. cient. argent. 26(1): 46 (1888)

MycoBank number: MB 978; Index Fungorum number: IF 978, Facesoffungi number: FoF 10324, 45 morphological species (Species Fungorum 2021), 2 species with molecular data.

Saprobic on leaves. Sexual morph: Ascomata appearing as black dots scattered on the upper surface, developing beneath a brown layer attached to the leaf surface, scattered, subglobose to circular, cupulate on drying, brown to dark brown, ostiole or papilla not apparent. Setae scattered, dark brown to black at the apex, erect. Wall of ascoma thicker at the apex, multi-layered, pseudoparenchymatous, comprising pigmented, thick-walled cells of textura angularis, with inner layer thinner, flattened, lightly pigmented to hyaline, thin-walled cells. Hamathecium lacking paraphyses. Asci 8-spored, bitunicate, clavate to ellipsoid, shortly pedicellate or sessile. Ascospores overlapping uni-seriate or bi-seriate, oblong-ellipsoid, obovoid, hyaline, septate or muriform, slightly constricted at the septa, smooth and thick-walled, lacking a gelatinous sheath or appendages. Asexual morph: Undetermined.

Type species: Chaetothyrium guaraniticum Speg. [as ‘guaranticum’]