Characters: Colonies are usually open branched, becoming bushy on upper reef slopes and in shallow lagoons. Main branches may have compact branchlets giving colonies a bushy appearance. Corallites are widely spaced and vary greatly in size, the largest being appressed and tubular. The coenosteum is fine, giving branches a smooth appearance.
Colour: Brown, with pale branch tips.
Similar Species: Acropora proximalis. See also A. vaughani, which has more uniform, less appressed radial corallites and greater development of incipient axial corallites.
Habitat: Turbid water around fringing reefs.
Abundance: Uncommon.
Taxonomic Note: Acropora inermis (Brook, 1891) is a synonym of Acropora horrida in agreement with Wallace (1999) and Wallace, Done and Muir (2012). Acropora inermis sensu Veron (2000a) remains under review.
Taxonomic References: Veron (2000a);
