Lenormandia muelleri Sond.

Scientific Description

Habit and structure. Thallus dark brown-red, 20–50(–80) cm high, probably perennial, much branched with 3–4 orders of elongate-ovate blades all with distinct stipes 1–10 cm long, the lower axis denuded and secondarily thickened and usually several cm long, compressed to terete and 1–2 mm broad; blades simple, ovate to elongate, arising from the midrib of older blades, margins entire, smooth to undulating, 5–20 cm long and (1–)2–4(–8) cm broad, midrib distinct, becoming heavily thickened in the stipes. Holdfast discoid, becoming branched, 2–20 mm across; epilithic or epiphytic (on Osmundaria). Structure. Apices cleft, apical cell conical, 30–50 µm in diameter (including very thick wall), axial cells cutting off probably 5 pericentral cells but these soon indistinct in transverse section; medulla irregular, 2–3 cells broad, cortex 2–3 cells broad, cells in surface view irregular, angular, 8–15 µm across L/D 1–1.5, with clear rhombic areolation in young blades. Trichoblasts on midrib of young blades and associated with reproductive organs, 0.5–1 mm long, basal cell 40–60 µm in diameter, L/D 1–2. Cortical cells uninucleate, medullary cells probably multinucleate; rhodoplasts discoid, chained in larger cells.

Reproduction. Gametophytes dioecious. Procarps on reduced trichoblasts, becoming polysiphonous as short, branched, outgrowths scattered on the blade surface. Carposporophytes with a basal fusion cell and much branched gonimoblast with clavate terminal carposporangia 40–60 µm in diameter. Cystocarps usually single, stalked, ovoid, 1–1.5 mm in diameter; pericarp ostiolate, 7–12 cells thick. Spermatangial organs in dense clusters on branches of trichoblasts at the base of short, flat, proliferations on branch surfaces, 40–80 µm in diameter and L/D 1–2.5. Tetrasporangial stichidia clustered, scattered on blade surface, often mainly on one tetrasporangia in opposite pairs, 60–80 µm in diameter.

Distribution.Port Elliot, S. Aust., to Wilsons Promontory, Vic and Bruny I., Tas.

Habitat. L. muelleri is a deep-water species.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 383–386 (2003)]