The new genus Aptrootia Lücking & Sipman is described for Thelenella terricola, an enigmatic terricolous and muscicolous, pyrenocarpous taxon known from Papua New Guinea and Costa Rica, and the new combination Aptrootia terricola (Aptroot) Lücking, Umaña & Chaves comb. nov. is introduced. Aptrootia is characterized by completely immersed perithecia with brown-black ostiolar region, surrounded by a white, cartilaginous thallus resembling that of Gomphillaceae. The hamathecium is typical of Trypetheliaceae, with thin, anastomosing paraphysoids embedded in a gelatinous matrix, but the dark brown ascospores are otherwise unknown within the family. The only known species was tentatively described in Thelenella, but hamathecium type and molecular data place Aptrootia within Trypetheliaceae.
