Nizymenia conferta (Harv.) Chiovitti, G.W.Saunders & Kraft

Scientific Description

Habit and structure. Thallus erect, medium red to dark red-brown, 5–15(–20) cm high, much branched from the margins, branches compressed, linear, (0.7–)1–2 mm broad, basally constricted and with rounded apices. Holdfast discoid, 2–6 mm across, with several terete to slightly compressed stipes 2–10 mm long and 0.5–2 mm in diameter; epilithic. Structure uniaxial, with four periaxial cells, the lateral two more strongly developed, and a prominent axial filament 60–100 µm in diameter throughout the thallus, densely surrounded by thick-walled rhizoids 5–9 µm in diameter. Cortex pseudoparenchymatous with angular, closely packed cells, inner ones 15–30 µm in diameter, outermost 2–3(–5) µm in diameter and L/D 1–1.5. Rhodoplasts discoid to elongate, few to numerous per cell.

Reproduction. Sexual thalli dioecious. Procarps formed in tufts of filaments on the branch margins, associated with extension of a lateral vegetative filament, and with the outer filaments of a tuft cutting off cells laterally from the upper 4–5 cells. Auxiliary cell intercalary, with one to three 3-celled carpogonial branches, post-fertilization connecting filament single and uniting with the auxiliary cell which produces a single gonimoblast initial and later a large fusion cell with radiating gonimoblast filaments bearing rows of 2–4 subspherical to ovoid carposporangia 6–9 µm in diameter. Cystocarps subspherical on the branch margins, basally constricted, 400–700 µm in diameter, with a thick pericarp and prominent depressed ostiole. Spermatangia on branched upper laterals of uniseriate filaments 6–9 µm in diameter, cells L/D 1.5–2, in tufts on the flat surface of branches. Tetrasporangia unknown.

Distribution. Geraldton, W. Aust., to Port Phillip Heads, Vic., and NW Tas.

Habitat. N. conferta is essentially confined to deep water on rough-water coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 405–407 (1994) added as Stenocladia australis]