The two most species-rich radiations of gall-inducing eriococcids are parasites of Eucalyptus: (1) the genus Apiomorpha Rübsaamen (ca 40 described species and many undescribed cryptic species), and (2) a monophyletic group composed of species currently placed in the genera Lachnodius Maskell, Opisthoscelis Schrader, Sphaerococcopsis Cockerell, Fragorbis Hardy and Gullan and Floracoccus Beardsley (ca 30 described species). We revise the genus Opisthoscelis Schrader, and erect the genus Tanyscelis gen. n. with Opisthoscelis pisiformis Froggatt as its type species. As a result of our taxonomic revision, Opisthoscelis has six species and Tanyscelis has 12 species. We describe the adult female and female gall of each species and galls of males for 10 species of Opisthoscelis and Tanyscelis, and provide photographs of the galls for most species. A key to the adult females of the species of both genera is included.