The Southern Hemisphere genus Leioderma Nyl. contains seven species: L. amphibolum (Knight) P. M. Jørg & D. Galloway, L. applanatum sp. nov., L. duplication (Mull. Arg.) comb, nov., L. erythrocarpum (Nyl.) comb, nov., L. glabrum sp. nov., L. pycnophorum Nyl., and L. sorediatum sp. nov. The genus has two subgenera (Leioderma, and Fuscoderma subgen. nov.) distinguished by differences in thallus morphology and the structures of asci and ascospores. Leioderma is closely related to Erioderma but differs in thallus habit, structure of cortex and ascus, and chemistry. Leioderma appears to be a Gondwanan genus. A key is given, and details of anatomy, morphology, distribution, ecology, phytogeography and taxonomy are discussed. A new, Lewderma-like, sorediate Parmeliella, P. subgranulata sp. nov., is described from New Zealand, and the related P. granulata Lamb, is recorded from New Zealand for the first time.

The genus Sagenidiopsis gen. nov. of uncertain family in the order Opegraphales is erected for a byssoid lichen which occurs in the cool temperate rainforests of the Macpherson Range of eastern Australia, S. merrotsii sp. nov. The genus is characterized by its byssoid thallus and bitunicate asci which have no amyloid structures apparent in the tholus. A byssoid thallus is without taxonomic significance at the family level, but is an ecological key character.

Notes are provided on the genus Ramonia and its four species represented in the British Isles, including R. dictyospora sp. nov. and R. nigra sp. nov.

The genera Hypotrachyna (Vainio) Hale and Pseudoparmelia Lynge are emended to include species previously accommodated in the genus Parmelina Hale. Pseudoparmelia endochromatica sp. nov., P. singularis sp. nov., Xanthoparmelia glomerulala sp. nov., X. karamojae sp. nov., and X. meruensis sp. nov. are described. The following combinations are proposed: Hypotraehyna afrorevoluta (Krog & Swinscow) comb, nov., H. aurulenta (Tuck.) comb, nov., H. damaziana (Zahlbr.) comb, nov., H. horrescens (Taylor) comb, nov., H. meyeri (Zahlbr.) comb, nov., H. minarum (Vainio) comb, nov., H. spathulata (Kurok.) comb, nov., H. spumosa (Asah.) comb, nov., H. swinscowii (Hale) comb, nov., Parmotrema vividum (Krog & Swinscow) comb, nov., Pseudoparmelia chlorea (Stizenb.) comb, nov., P. simplicior (Hale) comb, nov., P. usambarensis (Steiner & Zahlbr.) comb, nov., P. wallichiana (Taylor) comb, nov., Xanthoparmelia interrupta (Stizenb.) comb, nov., and X. kiboensis (Dodge) comb. nov. Xanthoparmelia cylindriloba Knox is reduced to synonymy with X. kiboensis.