Chondria curdieana (J.Agardh) Falkenb.

Scientific Description

Habit and structure. Thallus red-brown, fading to yellow-brown, (2–)5–12(–17) cm high, much branched irregularly radially for 3–4 orders, branches terete, often axillary in robust forms, lower branches 0.4–1 mm in diameter, ultimate branchlets 300–500(–900) µm in diameter, basally constricted. Holdfast discoid, attachment often by small haptera 0.3–1 mm across on prostrate branches; epilithic or epiphytic on Posidonia or larger algae. Structure. Apices rounded or usually slightly depressed, with an apical filament cutting off 5 pericentral cells and trichoblasts, the pericentral cells rapidly producing usually 3 series of quadrichotomous cortical cells, epidermal cells becoming (15–)20–25(–30) µm in diameter and L/D (2–)3–5(–7). Mature axes with large cortical cells and rhizoids outside the pericentral cells. Cell wall thickenings usually present in pericentral and inner cortical cells, on the inner walls or band-like around the cell and becoming hooked and lobed. Trichoblasts profuse at branch apices, 1–1.5 mm long. Cells multinucleate; rhodoplasts discoid to elongate, becoming chained in larger cells.

Reproduction. Gametophytes dioecious. Procarps on the suprabasal cell of trichoblasts, with a 4-celled carpogonial branch and lateral and basal multicellular sterile groups. Carposporophyte with a branched basal fusion cell and short branched gonimoblast bearing lachrimiform to clavate terminal carposporangia 70–100 µm in diameter. Cystocarps ovoid, subsessile, 1–2 mm in diameter, without a spur; pericarp ostiolate, with 10–12 erect filaments, 3–4 cells thick with slight cortication. Spermatangial plates as a lower branch of a trichoblast, discoid, 400–600 µm across, margin smooth and 2(–3) cells broad. Tetrasporangia occur in lesser branches, borne adaxially near the distal end of 1(–2) pericentral cells per axial cell, 120–200 µm in diameter.

Distribution.Houtman Abrolhos, W. Aust., to Waratah Bay, Vic., and northern Tas.

Habitat. C. curdieana is common on rough-water coasts of south-eastern Australia, epiphytic on seagrasses and various algae, usually in shallow water; stouter plants occur under rougher water.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 441–443 (2003)]