Sphacelaria fusca (Huds.) Gray

Scientific Description

Habit and structure. Thallus medium to dark brown, 0.5–2(–3) cm long, forming loose to fairly dense tufts, usually epiphytic, sometimes epilithic, rising from small basal discs. Branching of well developed axes frequent, irregularly radial, with laterals either indeterminate or somewhat determinate, alternate or opposite, arising at narrow to broad angles and reaching varying heights; phaeophycean hairs usually frequent, 15–25 µm in diameter. Axes (45–)60–80(–90) µm in diameter with segments L/B (0.7–)0.8–1.2(–1.5) and showing 3–5 longitudinal walls; laterals (25–)40–65 µm in diameter with segments L/B 1.0–1.5 and showing 1–3 longitudinal walls, decreasing only slightly to apical cells; secondary transverse walls absent to rare.

Reproduction. Propagula mostly with three, occasionally 2 or 4, slender, cylindrical arms each 200–400 µm long and 20–30(–35) µm in diameter, borne on a pedicel 240–500 µm long, and with a small, lenticular apical cell which does not develop further. Plurilocular and unilocular zooidangia unknown.

Distribution. In southern Australia, known from W. Aust., to Westernport Bay, Vic.

[After Womersley, Mar. Benthic Fl. Southern Australia II: 168 (1987)]