Amphiroa is a genus of thalloid red algae comprising 111 species. Specimens can reach around 30 cm in size. The thalli take a crustose form; dichotomous branches are formed. The organisms possess secondary pit connections. Amphiroa reproduces by means of conceptacles; it produces tetraspores. Its pore canals are lined with parallel filaments; the morphology of the pore canal is a key trait used to delineate species within the genus.