Abstract
Four new graphidoid and thelotremoid Graphidaceae are described from Australia, all supported by previously published molecular data. Fissurina bullata Mangold, Lücking & Lumbsch differs from other Fissurina species in having a strongly bullate thallus with large clusters of calcium oxalate crystals, in combination with a psoromic acid chemistry. Ocellularia australiana Mangold, Lücking & Lumbsch is similar to O. wirthii in having a white-grey thallus and in containing psoromic acid but differs in the loose cortex and the more irregular ascomata with partly fissured margins and often divided, thickly white-tipped columella, as well as slightly larger ascospores. Thelotrema fuscosubtile Mangold, Lücking & Lumbsch was previously confused with T. subtile but can be distinguished by the prominent ascomata and in the ascospores becoming pale brown. Finally, T. inspersoporinaceum Mangold, Lücking & Lumbsch differs from T. porinaceum in having an inspersed hymenium.