Pterocladiella caerulescens (Kütz.) Santel. & Hommers.

Scientific Description

Habit and structure. Thallus tufted, to 3 cm tall, red to reddish green, with terete prostrate axes 360–500 µm diam., attached by peg-like rhizoidal holdfasts, bearing erect axes that are terete below and 360–400 µm diam., ligulate above and to 3 mm wide. Lateral branches marginal, irregularly alternate to opposite, to 20 mm long, basally constricted and compressed to strongly flattened. Apical cell prominent; medulla of longitudinally elongate cylindrical cells 10–15 µm diam., with few to numerous rhizines; cortex of progressively smaller pigmented cells, the outermost layer of ellipsoidal cells c. 5 µm diam., these orientated obliquely distally and irregularly aligned in surface view.

Reproduction. Tetrasporangia forming in circular to oval subapical sori on both branch faces, ellipsoidal, 34–39 µm long, 25–30 µm diam., cruciately divided. Other reproductive structures not seen.

Distribution. Widespread in tropical to subtropical seas.

Habitat. Typically epilithic, from shallow water down to 20 m.

[After J.M. Huisman, G.H. Boo & S.M. Boo in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 264 (2018)]