The genus Thoris Pascoe is revised. Two species are described as new: T. octoguttata from Australia and T. brandti from New Guinea. Diagnoses of all other species are given and their terminaha described. T. moerens Blackburn is transferred to Allotisis Pascoe. A key to the eight species is provided. Phylogenetic analysis suggests that this genus be divided into three species-groups: the gilesi-group, the quinqueguttata-group and the septemguttata-group. Biogeographic implications of the genus are discussed on the basis of the genus' proposed phylogeny, present distribution and geological history of New Guinea and Australia.