Sargassum carpophyllum J.Agardh

Scientific Description

Habit and structure. Thallus pale to medium brown, to 46 cm tall, with a discoid-conical holdfast c. 12 mm wide giving rise to 1 or 2 terete stipes to 15 mm long and 1–2 mm diam. covered in radial branch scars. Primary branches subdistichous, compressed to subterete, smooth to slightly striated, 0.5–1.0 mm diam. Lower laterals lanceolate, serrulate to serrate, 25–45 mm long, 4.5–6.0 mm wide; apices obtuse; midrib vanishing just below the apex. Secondary branches distichous, subterete to compressed, smooth to striated, 0.5–1.5 mm diam. Upper laterals lanceolate or ovate-lanceolate, serrate-dentate, 10–30 mm long, 1.5–5.0 mm wide; apices usually obtuse; midrib prominent, vanishing just below the apex; base cuneate, asymmetrical, with prominent scattered cryptostomata. Vesicles spherical to slightly elongate, smooth, mutic or with 1–4 short foliar appendages, 1–3 mm diam., with terete or winged stalks. Reproductive branches zygocarpic; vesicles and leaves arising directly from receptacles (Fig. 55B). Receptacles monoecious, simple or loosely branched, smooth, terete, with rounded to acute apices, 1–3 mm long, 0.25–0.50 mm diam. Conceptacles unisexual; oogonia oval or bean-shaped, 68–102 µm long, 45–60 µm wide; antheridia possibly sessile 9–15 µm long, 5.5–11.0 µm wide.

Distribution. Known from several localities in the Indian and western Pacific Oceans, including northern W.A. and Qld.

Habitat. Epilithic in the subtidal.

[After Dixon & Huisman, Algae of Australia: Mar. Benthic Algae of North-western Australia, 1. Green and Brown Algae 269 (2015)]