Characters: Colonies consist of fused, flattened basal branches, forming extensive horizontal plates commonly over 2 metres across. The oldest parts of colonies are frequently fused into a solid plate. Corallites are widely spaced and mostly immersed, becoming nariform and sharp edged towards branch tips. Colour: Brown or green with pale margins. Similar species: Acropora solitaryensis and A. divaricata, which form colonies that are less flat and have upright branchlets. Habitat: Reef slopes. Abundance: Common at the Houtman Abrolhos Islands, south-western Australia, uncommon elsewhere.