Gracilaria coronopifolia J.Agardh

Scientific Description

Habit and structure. Thallus erect to partially decumbent, to 12 cm tall, red to purple (often with a patchy iridescence underwater), cartilaginous, subdichotomously branched; branches terete or slightly compressed, (2.0–) 3.5–4.5 (–5.0) mm diam., with blunt apices; structure apparently uniaxial, but central axis obscure, pseudoparenchymatous, with large medullary cells grading abruptly into a smaller-celled cortex.

Reproduction. Tetrasporangia scattered in the outer cortex, cruciately divided, 40–50 × 20–25 μm. Spermatangia in deep pits (“verrucosa-type”); conceptacles 40–50 μm wide. Cystocarps to 2 mm diam., deeply embedded in the thallus, surrounded by a well-defined ring of hyaline tissue.

Distribution. This Indo-Pacific alga is known from the Houtman Abrolhos Islands, Western Australia around northern Australia and possibly to Townsville, Queensland.

Habitat. Epilithic in the intertidal and subtidal.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 350–351 (2018)]