Delisea elegans J.V.Lamour.

Scientific Description

Habit and structure. Thallus medium red to dark red-brown, fading to yellow-grey, 10–30 cm high, complanately and alternately much branched, branches slender, terete to compressed, 250–500 µm broad above, 0.5–1 mm broad and subterete below where mostly denuded of ramuli. Lesser branches with regularly spaced, alternately distichous, terete ramuli 1–1.5 mm long and 100–200 µm in diameter near their base. Holdfast discoid, becoming knobby, 1–3 mm across with a single stipe; epilithic or occasionally epiphytic. Structure uniaxial, with a small apical cell, the subapical cell(s) cutting off two pairs of lateral and transverse periaxial cells, the lateral of the first pair producing the more strongly developed filament forming the alternate ramuli, with the lateral periaxial cell of the second pair remaining ovoid and not forming a distinct filament of elongate cells; the latter and the transverse periaxial cells contribute to the cortex near the compressed apices. Main branches 12–20 cells thick, the axial filament 20–50 µm in diameter, with a sheath of smaller cells; inner cortical cells ovoid, 30–100 µm in diameter, with a few intermixed small cells, outer cortical cells angular, 6–12 µm across, with occasional scattered gland cells. Rhodoplasts discoid, numerous per cell, becoming ribbon like in inner cells.

Reproduction. Gametangial thalli monoecious. Carpogonial branches unknown. Carposporophyte associated with the less well developed lateral periaxial filament, probably arising from the basal cell, thus lying between two ramuli, with a basal fusion cell adjacent to a group of darker-staining (nutritive?) cortical cells, and a short tuft of slender, branched, gonimoblast filaments with terminal elongate-ovoid carposporangia 20–60 µm in diameter. Cystocarps lying on the flat surface between ramuli near branch ends, sessile, 400–600 µm across with a thick pericarp (with inward growing branched filaments) and an ostiole. Spermatangial sori in scattered patches or covering the ramuli, with elongate spermatangia cut off from outer cortical cells, 2–3 µm in diameter. Tetrasporangia uncertain, possibly formed on small crusts.

Distribution.W. Aust., to Gabo I., Vic., and around Tas., New Zealand (Wellington south).

[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 339–340 (1996)]