Sebdenia polydactyla (Børgesen) M.P.Balakr.

Scientific Description

Habit and structure. Thallus erect, pale pink, flabellate, to 8–14 cm tall, arising from a discoid holdfast, dichotomously branched with rounded axils. Axes terete to slightly flattened, mostly soft but turgid, 2–4 mm diam. near the base and in some specimens cartilaginous, broadening to 8–12 mm wide, broadest just below dichotomies. Structure multiaxial, with a filamentous medulla of elongate cylindrical cells 15–20 µm diam. [L:B c. 10], grading to an outer medulla of stellate cells, 3 or 4 layers of large hyaline cells, then a small-celled cortex, the surface cells subspherical and 5–10 µm diam. Spherical to obovoid vesicular cells 25–35 µm diam., borne laterally on medullary filaments.

Reproduction. Reproductive structures not seen.

Distribution. Widely distributed in tropical and warm-temperate regions of the Indian Ocean.

Habitat. Epilithic, often on rocks in sandy regions of the subtidal.

[After J.M. Huisman & G.W. Saunders in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 302–303 (2018)]