Chamaebotrys boergesenii (Weber Bosse) Huisman

Scientific Description

Habit and structure. Thallus decumbent, with tangled axes attached to the substratum by short solid stipes. Axes dichotomously to trichotomously branched, irregularly moniliform, with spherical to oval segments 2–6 mm long and 2–5 mm wide, with moderately shallow constrictions between the segments and numerous adventitious branches that can form secondary holdfasts or fusions between adjacent segments. Septa between segments several cells thick. Structure with an outer cellular layer encasing a mucilage-filled cavity. Outer layer with a medulla of large hyaline cells (70–180 × 70–110 µm in surface view) subtending 2 or 3 layers of progressively smaller pigmented cortical cells 6–8 µm diam. Spherical vesicular cells 20–25 µm diam., solitary or paired and borne either on stellate cells arising from the inner surface of the medullary layer or directly on the medullary cells.

Reproduction. Spermatangia not seen. Mature cystocarps protuberant, with a well-developed pericarp. Tetrasporangia spherical to elliptical, cruciately divided, terminal, borne in nemathecial sori.

Distribution. Widespread in warmer waters.

Habitat. Generally found in protected positions on and under rock and coral ledges, it is occasionally found growing epizoically. Specimens have been collected from the upper sublittoral to depths of 40–50 m.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae:337–338 (2018)]