The largest of the 80 families of red algae is the Rhodomelaceae. A great many genera and species are restricted to Australasia, which is the major centre of diversity and distribution. Perhaps as a consequence, the Rhodomelaceae has remained relatively unstudied compared with most other red algal families even at the morphological/ anatomical level. This work studies selected tribes and genera, all of which have a strong Australasian component. Anatomical and molecular analyses have been undertaken on members of the tribes Amansieae, Pleurostichidieae, Streblocladieae and Sonderelleae. The results of these analyses have led to the description of two new genera, three new species, and one new tribe as well as the resurrection of two genera and the recombination of ten species. The taxonomic position and validity of the studied tribes and genera has also been established. This study will be of particular interest to taxonomic phycologists or anyone else interested in the marine botany of the Australasian region.