Galaxaura rugosa (J. Ellis et Solander) J. V. Lamouroux, 1816

    Thallus lightly calcified, 4-11 cm high, composed of short, entirely terete, intertwined, irregularly alternately branched axes 1-3 mm in diameter, evenly covered with reddish brown filaments. Assimilatory filaments stiff, both short (2-3 cells long, to 500 μm, with ovoid to spherical terminal cells to 35 μm in diameter) and long (to 1.6 mm, subtended by globose basal cells). Pseudoparenchymatous cortical layers absent. Medullary filaments colourless and loose, separated by a ring of calcification from the more compact, pigmented assimilatory filaments. Tetrasporangia cruciately divided, terminal on long assimilatory filaments.