The genus Amphiroa (Lithophylloideae, Corallinaceae, Rhodophyta) from the temperate coasts of the Australian continent, including the newly described A. klochkovana

Studies of Amphiroa (Lithophylloideae, Corallinaceae, Rhodophyta) from the temperate coasts of Australia provide new evidence that differences in tetrasporangial conceptacle pore canal anatomy are diagnostically significant in delimiting species within the genus. Differences in overall morphology and genicular anatomy are also reliable for delimiting species. These data are supported by examination of relevant type specimens. Four species occur in temperate Australian waters. Three (Amphiroa anceps, Amphira beauvoisii, and the newly described Amphiroa klochkovana) occur in southeastern Australia, and three (A. anceps, A. beauvoisii, and Amphiroa gracilis) occur in southern and southwestern Australia. Comparisons of A. beauvoisii and A. anceps have shown that they cannot be separated at species level morphologically but clearly differ in tetrasporangial conceptacle pore canal anatomy. This has important flow-on implications concerning specimen identification, reported geogeographic distribution and putative heterotypic synonymy of the two species. Relevant historical data, a species key and a synoptic description of Amphiroa also are included.