Taxonomy of the genus Amphiroa (Corallinales, Rhodophyta) in the southern Baja California Peninsula, Mexico

Studies of the genus Amphiroa (Corallinales, Rhodophyta) along the southern Baja California Peninsula, Mexico, were undertaken to determine how many species were present and to assess the characters that have been or could be used in species delimitation. After analysis of 800 specimens from 60 localities, we conclude that five species are present: A. valonioides Yendo, A. misakiensis Yendo, A. vanbosseae Lemoine, A. rigida Lamouroux and A. beauvoisii Lamouroux. Amphiroa brevianceps Dawson and A. magdalensis Dawson are considered heterotypic synonyms of A. misakiensis. Characters used here for the first time to delimit species of Amphiroa include shape of gametangial conceptacle chambers, ontogeny of the pore of the gametangial conceptacle, the type of spermatangia present, the position of gonimoblast filaments and the form of the cortical cells. Characters used in species delimitation in Amphiroa are discussed in detail and a key to the species found in southern Baja California is provided.