Habit and structure. Thallus (gametophyte) red, 5–10 cm high, subdichotomously branched every 3–10(–15) mm below, often 1–2(–3) cm apart above, not constricted, branches 1.5–2 mm in diameter, apices rounded. Holdfast discoid, 1–3 mm across; epilithic. Structure multiaxial, developing a central core of entwined filaments 2.5–10 µm in diameter, from which radiate medullary filaments 3–5 µm in diameter, with the cortex 2–3(–4) cells thick, of globose to pyriform rhodoplastic cells 5–12.5 µm long and 5–7.5 µm in diameter, outwardly smaller, and without any colourless utricles. Tetrasporophyte filamentous, cells 2–8 µm in diameter, L/D 5–8.
Reproduction. Outer cortical cells released as monosporangia 5–6 µm in diameter. Sexual thalli monoecious. Carpogonial branches 3-celled, developing on outer medullary cells, with the hypogynous cell forming three sterile branches, 1-celled, 2-celled and 3-celled (plus a further cell from its base) and the basal cell producing sterile filaments which form the involucre after fertilization. Fertilized carpogonium cutting off initials which form the gonimoblast with terminal chains of ovoid carposporangia 12–15 µm long and 7–10 µm in diameter; a basal fusion cell present. Cystocarps 110–225 µm in diameter, ostiolate, with a well developed involucre. Spermatangia cut off from outer cortical cells as a surface layer, ovoid, 3–4 µm in diameter. Tetrasporangia borne terminally or laterally, sessile or pedicellate, cruciately divided, 10–11 µm in diameter and 15–20 µm long.
Distribution. From Eucla, W. Aust., to Walkerville, Vic., and the N coast of Tas.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 107–108 (1994)]