Haloplegma duperreyi Mont.

Scientific Description

Habit and structure. Thallus red-brown to grey-red, flat and complanately branched, 1–10 cm high, flabellate to lobed, becoming divided or lacerate, lobes expanding upwards to (1–)2–4 cm broad, mostly 400–600 µm thick, margins smooth to slightly ruffled. Stipe 2–5 mm long, 1–2 mm in diameter, holdfast 2–8 mm across, rhizoidal; epilithic or on shells (one specimen on old axes of Doxodasya bulbochaete). Structure. Marginal apices regularly fringing the blades, with primary apices and filaments separated by numerous secondary apices from lateral filaments. Apices with alternate laterals from 3–6 cells below the apical cells, walls more-or-less transverse, apical cells 10–18 µm in diameter and L/D 1–1.5. Laterals of apical filaments uniting with next adjacent filaments to form a rectangular network, with other irregular filaments, the outer cells developing short branch clusters. Cells of internal filaments 25–45 µm in diameter and L/D 3–7, outer clusters 45–100 µm long with ovoid basal cells 15–30 µm in diameter, branched 1–3 times with terminal unbranched rows of 2–4 cells, 8–14 µm in diameter, isodiametric to slightly ovoid. Cells multinucleate; rhodoplasts discoid to elongate, ribbon like in larger cells.

Reproduction. Gametophytes not observed. Tetrasporangia terminal on cells of outer clusters, subspherical to slightly ovoid, 20–40 µm in diameter, tetrahedrally divided.

Distribution. NW Aust., Qld, and Lord Howe I. In southern Australia, known from Elliston, N Spencer Gulf, Kangaroo I., and Robe and Nora Creina, S. Aust.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIC: 282–284 (1998)]