Amphiroa foliacea J.V.Lamour.

Scientific Description

Habit and structure. Thallus to 14 cm tall, calcified, highly variable in habit; branching predominantly or exclusively dichotomous and multiplanar. Intergenicula generally compressed to flattened, 7–20 mm long and 2–6 mm wide, occasionally with a central midrib, but also terete (commonly at branch tips) and 5–16 mm long and 0.75–2.00 mm diam. Genicula composed both of core region and peripheral region cells, the former containing 5–9 arching tiers of cells with 2–8 tiers of longer cells followed by a tier of shorter cells, genicula absent from 25–50% of the branching points. Calcified collars absent.

Reproduction. Tetrasporangial conceptacles uniporate, scattered over intergenicula and protruding above the surrounding surface. Conceptacle pore canals flanked by filaments projecting laterally towards the pore canal; rings of large block-shaped cells absent. Mature conceptacle chambers 205–350 μm diam. and 95–160 μm tall; tetrasporangia 20–30 μm diam. and 55–80 μm long. Gametangial and carposporangial thalli not recorded from Australia.

Distribution. Worldwide distribution.

Habitat. epilithic in the intertidal down to 26 m.

[After A.S. Harvey, W.J. Woelkerling & J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 101–104 (2018)]