Lomentaria monochlamydea (J.Agardh) Kylin

Scientific Description

Habit and structure. Thallus dark red-brown, forming entangled clumps 2–5 cm high and across, with basal stolons producing erect, mostly simple, compressed blades 0.5–2 cm high and 0.5–2 mm broad, basally constricted and tapering to a rounded apex. Stolons branched, often curved, with erect blades 1–3(–5) mm apart, terete and 300–800 µm in diameter, attached by small haptera to the substrate or other branches; epilithic or on solid substrates. Structure multiaxial, with apical cells producing an interconnected network of medullary filaments 4–6 µm in diameter and bearing ovoid secretory cells 5–8 µm in diameter. Cortex 3–4 cells thick, the inner cortex of 2–3 cells with an outer layer of ovoid or isodiametric cells 10–22 µm across, a mid layer of slightly larger cells and an inner layer of elongate cells connected to the medullary filaments and also bearing occasional secretory cells, and a sparse outer cortex of small cells, scarcely forming rosettes. Older parts and stolons hollow but cortex 4–6 cells thick. Branch constrictions solid, pseudoparenchymatous. Rhodoplasts discoid, often in chains.

Reproduction. Gametangial thalli unknown. Tetrasporangia in irregular, depressed, sori 200–500 µm across, cut off inwardly from small cells lining the depression, subspherical to pyriform, 30–50 µm in diameter, tetrahedrally divided.

Distribution.Port Stanvac, S. Aust., to Port Phillip Heads, Vic., and Coffs Harbour, N.S.W.

Habitat. L. monochlamydea is usually epiphytic on Posidonia and Amphibolis.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 140–142 (1996)]