Incendia undulata K.R.Dixon

Scientific Description

Habit and structure. Thallus deep red to orange-red, especially at the margins, with raised concentric bands. Plants ±expansive crusts with small often imbricate orbicular lobes that are largely free of the substratum. Hypothallus composed of regularly parallel filaments of elongate cells 23–39 µm long and 6–8 µm tall proximally but flaring to 8–12 µm distally; these giving rise to assurgent perithallial filaments above and multicellular rhizoids below from their enlarged distal ends. Lower perithallus consisting of filaments of long slender cells that arise at narrow angles (to 50°) from the distal upper surfaces of hypothallial cells, frequently bearing obliquely orientated projections that form secondary pit connections with adjacent cells. Upper perithallus of elongate cells (8–20 µm long and 3–6 µm diam.) below, decreasing in length towards the surface; assurgent filaments terminated by isodiametric cells c. 4 µm diam. with rounded ends. Bullet-shaped hairs present within the upper perithallus, to 30 µm long and 18 µm diam. Rhizoids long, slender, multicellular, c. 8 µm diam.

Reproduction. Reproduction not observed.

Distribution. North-western Australia; also in Vanuatu and the Philippines.

Habitat. Occurs in the shallow subtidal.

[After K.R. Dixon in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 215–216 (2018)]