Asteromenia poeciloderma Huisman & G.W.Saunders

Scientific Description

Habit and structure. Thallus peltate to ligulate, decumbent, deep red with a mottled iridescence in situ, irregularly dichotomously branched with an inconspicuous primary stipe and numerous secondary peg-like attachments to the substratum. Branches flattened, to 10 mm wide in lower portions, tapering to 3–4 mm wide near the apices, to 500–600 μm thick, with marginal spines throughout, often forming marginal anastomoses with adjacent branches. Medulla of 3–6 layers of large hyaline cells; cells centrally 200–300 μm diam., grading to an outer medulla of smaller cells, then a cortex of 5 or 6 layers of progressively smaller pigmented cells. Surface cells of upper cortex 2.5–4.0 μm diam., those of the lower cortex slightly larger, to 5 μm diam. Surface hairs common, of two types: longer hairs forming in clusters on both surfaces, 25–35 μm long, c. 3 μm diam., with a dark-staining slightly broader distal half; shorter hairs common on upper cortical cells, often covering the surface, less so on the lower cortex, 10–12 μm long, c. 1.5 μm diam. Cells of outer medulla/inner cortex commonly with irregularly shaped inclusions, these possibly causing iridescence.

Reproduction. Cystocarps on the upper surface; pericarp hemispherical with a slightly elongated neck, to 1200 μm diam. Tela arachnoidea absent. Gonimoblast subspherical to pyriform, composed entirely of carposporangia. Other reproductive structures not observed.

Distribution. Known only from Mermaid and Clerke Reefs, Rowley Shoals, north-western Australia.

Habitat. Epilithic in the subtidal.

[After J.M. Huisman & G.W. Saunders in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 324 (2018)]