Delisea pulchra (Grev.) Mont.

Scientific Description

Habit and structure. Thallus medium to dark red-brown, fading to yellow-grey, 10–35 cm high, much branched complanately from the margins, branches compressed, axes 500–800 µm broad, with regular, alternate, evenly spaced, acute, compressed marginal spinous ramuli (0.5–)1–2(–3) mm long, basal width 250–400 µm, tapering evenly, axes becoming thickened and terete below, (1–)2–3 mm in diameter near the holdfast, often denuded below. Holdfast discoid, 2–8 mm across, usually with a single stipe; epilithic. Structure uniaxial, with a small apical cell, the subapical cell(s) each cutting off two pairs of lateral and transverse periaxial cells, the first pair forming the more strongly developed lateral periaxial filament on alternate sides and developing into the lateral spinous ramuli, with the opposite lateral filament passing towards the sinus between spines and the transverse periaxial cells contributing to the cortex. Spinous ramuli closely adjacent near apices, becoming separated below. Main branches becoming 8–15(–26) cells thick, the axial filament 50–140 µm in diameter with a surrounding sheath of small cells, the inner cortical cells ovoid, 25–50 µm in diameter and with intermixed small rhizoidal cells, outer cortical cells 4–6 µm in diameter, with scattered, larger, subsurface cells not covered by outer cells and appearing "gland like" in surface view with a rosette of outer cells. Rhodoplasts discoid, numerous per cell, often ribbon like in inner cells.

Reproduction. Gametangial thalli monoecious or dioecious. Carpogonial branches unknown. Carposporophyte with a basal fusion cell, a tuft of branched, slender, gonimoblast filaments, and terminal elongate-ovoid carposporangia 20–45 µm in diameter. Cystocarps on the flat surface near branch ends, sessile, 0.5–1 mm in diameter, with a thick pericarp and an ostiole directed forwards and outwards. Spermatangial sori on broadened branch ends, with the outer cortical cells each cutting off several elongate, tapering, spermatangia 2–3 µm in diameter. Tetrasporangial plants with prominent, raised, nemathecia 50–90 µm thick, near branch ends, tetrasporangia elongate-ovoid, 30–55 µm long and 10–15 µm in diameter, obliquely divided, among elongate-clavate unicellular (rarely 2-celled) paraphyses 50–65 µm long and 6–11 µm in diameter; paraphyses often cutting off several small cells apically.

Distribution.Dongara, W. Aust., around southern Australia and Tas., to Caloundra, Qld. New Zealand; Subantarctic Islands; Antarctic Peninsula.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 342–346 (1996)]