- Reference
- Mar.Benth.Fl.S.Australia 276 (1998)
- Conservation Code
- Not threatened
- Naturalised Status
- Native to Western Australia
- Name Status
- Current
Scientific Description
Habit and structure. Thallus erect, spreading, medium to dark red-brown, 5–15 cm high with 1–3 corticate main axes and prominent spreading, corticate lateral branches 1–5 cm long, with dense, overlapping lateral branchlets. Holdfast 2–8 mm across, rhizoidal; epilithic or epiphytic. Structure. Branching at apices alternate and distichous, apical cells dividing slightly to distinctly obliquely, increasing from 10–25 µm in diameter and L/D 1–2 to 200–500 µm in diameter and L/D 1–1.5(–2) in axial cells in lower parts. Indeterminate lateral branches developing from determinate branchlets and usually more-or-less distichously arranged, but determinate branchlets not clearly distichous due to crowding and curving of pinnules; branchlets dense and overlapping, with unbranched ends 40–100 µm and 3–8 cells long, pinnules curved and unbranched with median cells (20–)30–50 µm in diameter and L/D (1–)1.5–4, growing ends of axes and branchlets emergent or often overtopped by laterals from below. Rhizoidal cortication commencing on mid to upper axes, with lower axes becoming 1–2 mm in diameter, rhizoids loosely to densely entwined. Cells multinucleate; rhodoplasts elongate, ribbon like in larger cells and orientated lengthwise.
Reproduction. Gametophytes dioecious. Procarps borne on short 3–7-celled branchlets, with the fertile central cell bearing two periaxial cells, one (the supporting cell) cutting off a terminal sterile cell and a 4-celled carpogonial branch, the other periaxial cell forming a short sterile branchlet of 2–4 cells. The auxiliary cell cuts off 3–4 successive gonimolobe initials giving rounded groups 100–200 µm across of ovoid carposporangia 10–15 µm across; basal carposporophyte cells fuse and enlarge, with broader pit-connections. Curved branchlets from cells below the carposporophyte form an involucre. Spermatangial heads are borne adaxially on lower cells of branchlets, ovoid, 12–22 µm in diameter and L/D 2–3. Tetrasporangia adaxial on pinnules of branchlets, pedicellate, subspherical, 25–45 µm in diameter, tetrahedrally divided.
Distribution. King George Sound, W. Aust., to Port Phillip Heads, Vic.
Habitat. Subtidal, generally on hard substrata.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIC: 276–278 (2003)]