Three species of Mastophora (Rhodophyta: Corallinales, Corallinaceae) in the tropical Indo-Pacific Ocean: M. rosea (C. Agardh) Setchell, M. pacifica (Heydrich) Foslie, and M. multistrata sp. nov

Abstract

Three species of Mastophora (Corallinaceae, Corallinales, Rhodophyta) were found in extensive studies of nongeniculate coralline algae in various areas of the tropical Indo-Pacific, including French Polynesia, Fiji, Ryukyu Islands (Japan), and Taiwan. Two species are delicate and leafy but are distinguishable on morphological grounds. Mastophora rosea plants are taeniform, dichotomously branched, and weakly calcified and have rolled margins. Their thalli show very little secondary growth, with only occasional small round patches at the surface. Tetrasporangial and carposporangial conceptacles are very high (330–640 mm) and dome-shaped to almost spherical. Mastophora rosea plants collected during this study stand out in the water because of their bluish-purple colour. Mastophora pacifica has more strongly calcified thalli that are irregularly branched, with abundant secondary growth and the development of loosely attached, crispy layers. Tetrasporangial and carposporangial conceptacles are conical (280–550 mm high). Thallus colour in M. pacifica varies substantially depending on where it is growing, ranging from violet brown to dark red to greyish ruby, but are mostly pale-pink to reddish-purple in their submerged living state. Mastophora multistrata sp. nov. plants are hard and robust. Their thalli are made up of tightly packed layers that are evident only in section. Tetrasporangial conceptacles are generally low (315–490 mm high) and dome-shaped. In their living state, M. multistrata plants are usually deep-purple plum coloured.