The genus Coenogonium Ehrenb. in Tasmania comprises seven species. New to science are: C. atherospermatis Kantvilas, Rivas Plata & Lücking, endemic to Tasmania and characterized by pale yellowish beige apothecia and relatively small ascospores, 6–8·5×2·5–3 µm; C. urceolatum Kantvilas, Rivas Plata & Lücking, likewise endemic to Tasmania and characterized by orange, urceolate apothecia, 0·3–0·4 mm wide, and uniseriate ascospores, 8·5–11×2·5–3 µm; and C. australiense Kantvilas & Lücking, recorded from Tasmania, South Australia and New South Wales, and characterized by orange apothecia, 0·5–2 mm wide, and relatively broad ascospores, 10–14×3–4·5 µm. Also treated are C. lutescens (Vĕzda & Malcolm) Malcolm (Tasmania and New Zealand) and three widespread taxa, namely C. implexum Nyl. (Southern Hemisphere), C. luteum (Dicks.) Kalb & Lücking and C. pineti (Schrad. ex Ach.) Lücking & Lumbsch (both subcosmopolitan). All species are described in full from Tasmanian collections and illustrated, and their ecology, variation and affinities to related species are discussed. The Tasmanian taxa are also discussed in the context of the Australasian lichen biota.