Sargassopsis decurrens (Turner) Trevis.

Scientific Description

Habit and structure. Thallus pale to medium brown, to 80 cm tall, with a discoid-conical holdfast 5–15 mm wide, usually giving rise to a single primary axis that is simple or branched, slightly compressed, verrucose, with branch residues, to 12 cm long and 2–4 mm wide. Primary branches distichous, with a prominent midrib and lateral wings, 5–15 mm wide. Primary laterals complanate with primary branches, alternate, simple or divided, with or without a basal constriction, 2–5 cm long and up to 10 mm wide, tapering evenly toward the apex. Secondary branches arising in axils, alternate, distichous, with simple or divided laterals to 2 cm long and 3–4 mm wide. Cryptostomata irregularly arranged or in vague straight lines (on smaller laterals). Vesicles borne in axils, spherical, with a short stalk, to 6 mm diam., mutic or with a slender mucro 2–10 mm long. Receptacles on upper ramuli, stalked, simple or once-divided, terete, smooth, linear-lanceolate, 3–8 mm long, 0.5–1.0 mm diam.

Distribution. Known from Bahrain, Iran, Kuwait, Qatar, Saudi Arabia, the United Arab Emirates, Pakistan and east to New Caledonia. In Australia it occurs from Cape Naturaliste, W.A., around northern Australia to Keppel Bay, Qld. Also in the upper Spencer Gulf, S.A.

Habitat. Epilithic in the subtidal, usually forming beds.

[After Dixon & Huisman, Algae of Australia: Mar. Benthic Algae of North-western Australia, 1. Green and Brown Algae 250-251 (2015)]