- Reference
- Analecta Algol. 41 (1892)
- Conservation Code
- Not threatened
- Naturalised Status
- Native to Western Australia
- Name Status
- Current
Scientific Description
Habit and structure. Thallus erect, medium red-brown, 3–15 cm high, irregularly alternately branched, usually with a main axis and well-developed laterals, corticated with rhizoids on mid and lower parts, ecorticate above. Holdfast rhizoidal, 2–8(–12) mm across, epiphytic on Posidonia, Amphibolis or larger algae, or epilithic. Structure. Axial cells 27–55 µm in diameter near apices and L/D 1.5–2, 200–700 µm in diameter and L/D 2–4 below, bearing spirally arranged ecorticate branched branchlets tapering from 25–55(–100) µm in diameter, cells L/D 2–3, to 12–20(–27) µm in diameter, cells L/D 1.5–3(–4), near their apices, upper parts usually curved; cortical rhizoids 10–20 µm in diameter, cells L/D 3–8(–12). Cells multinucleate; rhodoplasts discoid to elongate.
Reproduction. Gametophytes dioecious. Carpogonial branches borne on the subterminal cell of fertile axes 4 to several cells long, the subterminal cell bearing the 4-celled carpogonial branch and the third cell bearing 2 opposite, sterile, periaxial cells, with the terminal and 2 sterile periaxial cells enlarging and becoming rounded. Post-fertilization the supporting cell cuts off an auxiliary cell and the carpogonium cuts off two connecting cells, with the carpogonial branch cells partly fusing. The auxiliary cell cuts off an apical gonimoblast initial which produces a first gonimolobe, then successively 3 or 4 more, each 180–540 µm across, with subspherical carposporangia 10–27 µm in diameter; the supporting cell and sterile cells of the procarp fuse to form a darkly-staining triangular mass with 3 projecting cells. The fourth cell of the fertile axis and lower axial cells produce curved involucral filaments around the carposporophyte. Spermatangial heads are elongate, 35–50 µm in diameter and L/D 2–4, sessile on lower cells of the branchlets, with 5–8 axial cells and outer spermatangia 2–3 µm in diameter. Tetrasporangia are borne on lower cells of the branchlets, sessile or on 1–2-celled pedicels (which may produce a further tetrasporangium or a small fascicle), subspherical, 25–50 µm in diameter, tetrahedrally divided (rarely octosporangia).
Distribution. North Beach, Perth, W. Aust., to Flinders, Vic., and SE Tas.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIC: 292–293 (1998)]