Peyssonnelia clathrata K.R.Dixon

Scientific Description

Habit and structure. Thallus red to brownish red, especially in older parts of the plant, with faint radial striae and concentric bands, composed of crisp but flexible moderately calcified thin prostrate blades that form a closely appressed but not tightly adherent crust. Sections of the mature perithallus resistant to staining with aniline blue; hypothallus readily staining. Hypothallus composed of mostly unbranched parallel filaments; cells rhomboidal in radial vertical section, 17–38 µm long and 17–25 µm tall, their corners angular near the thallus margin but rounded proximally. Perithallus composed of assurgent filaments, the large broadly attached basal perithallial coxal cells giving rise to 2 much narrower assurgent filaments that generally remain unbranched. Perithallial filaments usually short, to 3 or 4 cells long, although thicker parts of the thallus occasionally develop where the filaments become up to 8 cells long. Hypothallial and lower perithallial cells vacuolate towards the margin. Mature cells densely packed with small discoid starch grains. Hairs absent. Rhizoids unicellular, to 170 µm long and 10 µm diam., cut off the lower distal corners of hypothallial cells.

Reproduction. Reproduction not observed.

Distribution. Known only from the Kimberley coast, north-western Australia.

[After K.R. Dixon in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 217 (2018)]