Ptilophora wilsonii Huisman, G.H.Boo & S.M.Boo

Scientific Description

Habit and structure. Thallus erect, to 25 cm tall, red to purple-red, arising from a fibrous holdfast from which ligulate proliferous branches to 2 cm long also develop. Erect axes percurrent, distichous, pinnately branched to 3 orders, the final order often remaining determinate, occasionally with proliferous branches from the surface; all branches flattened, although the primary axes becoming slightly thickened centrally in older parts, to 250–800 µm thick; primary axes to 4 mm wide; determinate branches 3–6 mm long, 1.0–1.5 mm wide, 100–150 µm thick, mostly with rounded apices and a prominent hemispherical apical cell, generally of uniform width but slightly narrower at the base of the branch; branch axils rounded. Medulla of elongate thick-walled cells and rhizines; inner cortex of larger isodiametric cells; a layer of rhizines transected by files of cortical cells, and an outer cortex of small pigmented cells that are rounded-oblong in surface view and 4–7 µm wide.

Reproduction. Tetrasporangia borne in the cortex of flattened proliferous branches arising from distal parts of determinate branches, the entire branch surface bearing sporangia, ellipsoidal, to 50 (–70) µm long and 30–35 µm diam., decussately divided. Other reproductive structures not observed.

Distribution. Known from several collections from deep water off Ningaloo, Western Australia.

Habitat. Epilithic in deep water.

[After J.M. Huisman, G.H. Boo & S.M. Boo in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 251–253 (2018)]