Galaxaura marginata
Rhodophyta, Galaxauraceae
Authority: (Ellis et Solander) Lamouroux
Hawaiian name: la`au kanaka
Characteristic feature: Flattened calcified branches.
Description: Plants to 12 cm tall, distinctly compressed, wine red, more or less dichotomously branched, fronds often corymbose; axes and branches subcylindrical when young, axes sometimes retaining cylindrical form; mature plants with margins slightly raised and flat surfaces sometime channelled; axes 1.0-2.5 cm wide, jointed at dichotomies; only rarely bearing coloured hairs. Gametophytes and sporophytes dimorphic in anatomy, but both phases similar in habit. Sporophytes having outer and inner cortices; outer cortex consisting of rounded colourless parenchyma-like stalk cells bearing distally loosely arranged, coloured epidermal cells singly or in pairs, the cells ellipsoidal to sub-globose and sometime pointed, 25-40 µm broad by 30-60 µm long, these cells usually not touching; inner cortex consisting of two layers of globose or somewhat rectilinear cells 50-90 μm diam. Gametophytes dioecious; differing from sporophytes in having tightly compacted "epidermal" cells bearing spinelike protuberances of variable size, shape, and density; inner cortex like that of sporophytes; both with colourless periclinally oriented medullary filaments, 8-12 µm diam. Tetrasporangia borne laterally in groups of 2-3 on outer cortical cells.
Habitat: Low intertidal to subtidal, more common subtidally on open coasts.
Hawaiian distribution: Recorded from O`ahu, Maui and Hawai`i.
Other: Other Galaxura species have distinct hollow cylindrical branches.