Platyclinia ramosa Womersley

Scientific Description

Habit and structure. Thallus light to medium red to yellow-red, 4–10 cm high, much branched marginally, main axes 5–15 mm broad, laterals 3–6 mm broad, tapering to 1–2 mm broad, margins crisped to convolute, apices rounded; veins absent. Base of main axes tapering to a short, slender stipe. Holdfast discoid; epiphytic. Structure. Growth marginal with numerous very small apical cells, segmenting to irregularly arranged cells with frequent intercalary divisions, mature cells angular, isodiametric to slightly elongate, 20–35 µm across; blades monostromatic near margins, becoming tristromatic and 30–90 µm thick, cortical cells equivalent, polystromatic near the base. Cells multinucleate; rhodoplasts discoid.

Reproduction. Gametophytes dioecious. Procarps scattered, details not observed. Carposporophytes with a central fusion cell and a weft of gonimoblast filaments over the cystocarp floor, producing numerous erect chains of 2–4 ovoid carposporangia 20–40 µm in diameter. Cystocarps scattered, 1–1.5 mm across, hemispherical and with a collar; pericarp ostiolate, 3–5 cells thick, thicker at the collar. Spermatangial sori scattered, relatively small and irregular in shape, some becoming confluent, with cortical initials producing elongate spermatangia in blocks corresponding to the primary cells. Tetrasporangial sori scattered, ovate, with tetrasporangia cut off from primary cells and lying largely in one layer of mixed ages, with outer cover cells; tetrasporangia subspherical, 40–70 µm in diameter.

Distribution.Only known from Point Peron, W. Aust., Elliston, and Point Avoid, Yorke Pen., S. Aust.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 105–107 (2003)]