AbstractThe Tasmanian species of the family Thelotremataceae with thin-walled ascospores and exfoliating, chroodiscoid apothecia are studied in detail. Problems in the delimitation of genera are discussed, and characters such as the morphology of the apothecia, structure and form of the exciple, presence of periphyses, ascus structure, ascospore morphology and thallus chemistry are evaluated. The concept of the typically foliicolous genus Chroodiscus (Müll. Arg.) Müll. Arg. is expanded to include corticolous and terricolous species, and the new taxa C. asteliae Kantvilas & Vězda, C. australis Kantvilas & Vězda, C. australis subsp. tasmanicus Kantvilas & Vězda, C. lamelliferus Kantvilas & Vězda and C. minor Kantvilas & Vězda are described and illustrated. The related Australasian species, C. megalophthalmus (Müll. Arg.) Vězda & Kantvilas is also treated. Two new genera are also described. Pseudoramonia Kantvilas & Vězda, based on the Venezuelan species, P. stipitata (Vězda & Hertel) Kantvilas & Vězda, is introduced to accommodate P. richeae Kantvilas & Vězda; Topeliopsis Kantvilas & Vězda is described to include the Tasmanian taxa, T. muscicola Kantvilas & Vězda and T. rugosa Kantvilas & Vězda, and the North American species T. toensbergii Vězda & Kantvilas.