Cystophora moniliformis (Esper) Womersley

Scientific Description

Habit and structure. Thallus dark brown (often medium brown near apices), 0.5–2(–4) m long, with robust axes and fastigiate laterals. Holdfast discoid-conical, 0.5–2(–3) cm across, with a single, terete to compressed stipe 0.5–2 cm long and 2–8 mm in diameter; epilithic. Primary axis strongly compressed, (0.3–)0.5–1.5(–2) cm broad and 2–3(–7) mm thick centrally, usually relatively straight, alternately distichously branched from the edges; secondary axes 2–20(–100) cm long, occasionally developing into long axes, similarly branched to the primary axes; smaller tertiary axes often present. Laterals fasciculate, much branched alternately, essentially in one plane but with the ramuli becoming displaced, with slender, terete, much branched ramuli 0.2–0.5 mm in diameter; laterals usually lost below, with stubby, rounded, branch residues. Vesicles absent.

Reproduction. Thalli monoecious. Receptacles simple or branched, 0.5–1.5(–4) cm long and 0.5–1 mm in diameter, moniliform-torulose when fresh, drying strongly moniliform. Conceptacles bisexual, adjacent, with ostioles scattered or tending to two rows; oogonia sessile, ovoid, 80–120 µm long and 60–80 µm in diameter; antheridia sessile or on branched paraphyses, elongate ovoid, 25–35 µm long and 10–16 µm in diameter.

Distribution. From Cape Naturaliste, W. Aust., around southern Australia and Tas., to Port Stephens, N.S.W. Lord Howe I.

Habitat. It is often common (1–4 m deep) with moderate to strong water movement; on rough-water coast it is confined to rock pools or areas with slight shelter, extending to 28 m deep.

[After Womersley, Mar. Benthic Fl. Southern Australia II: 370–372 (1987)]