Shell small to medium-sized for subfamily (largest species to 190 mm SL), high-spired, fusiform; axial sculpture of short, narrow, sharply rounded ribs, forming one or more rows of nodes at intersections with spiral cords; shoulder angulation often sharp, keel-like in some species; outer lip weakly convex, with paired crenulations at its edge, its inner side with short smooth lirae; adapical notch absent; entrance fold to siphonal canal prominent, often keel-like, much more strongly expressed than the very weak columellar folds; abapical folds on inner edge of siphonal canal absent; parietal ridge prominent, rounded. Radula of type species described and figured by Verco (1895: pl. 3, fig. 8) as Fasciolaria coronata Lamarck, 1822, a junior synonym.

Morphologically, shells assigned to Australaria cover a range of variation similar to those of Lugubrilaria gen. nov. and Kilburnia gen. nov.. Recent specimens, which Wilson (1994) treated as the single highly variable and widespread temperate Australian taxon Pleuroploca australasia, vary in the strength and number of spiral cords, but all have at most a single row of nodes at the shoulder angulation. In some specimens of the typical form of A. australasia from South Australia and Victoria, nodes are entirely absent, and the shoulder angulation is rounded. Cotton (1953) divided the Australian material into several species, collectively ranging from southern Queensland to Western Australia. We tentatively prefer this approach in view of the nonplanktonic mode of development in Australaria and the demonstrated genetic divergences among populations in other temperate Australian gastropod taxa with this type of development. However, molecular sequence data are needed to clarify the specific composition of Recent members of the genus.

Although we cannot unambiguously separate the South African Kilburnia from the Australian Australaria on shell characters, we provisionally maintain them as distinct genera because of their likely long separate histories. Broad indirect support for this action comes from molecular data and phylogenetic relationships in other largely tropical clades that have endemic, separate South African and Australian temperate representatives, including Turbinidae (Williams, 2007), Cypraeidae (Meyer, 2003), and Littorinidae (Reid & Williams, 2004). Again, molecular work is needed to settle this matter.