Dictyopteris muelleri (Sond.) Reinbold

Scientific Description

Habit and structure. Thallus medium to dark brown, usually 20–40 cm long, with one to several complanate fronds arising from a matted rhizoidal holdfast 0.2–2.0 cm across and 0.2–1.0 cm long, epilithic. Growth from a row of 4–8 apical cells in a slightly depressed apex, with an entire margin below the apex. Fronds subdichotomously to alternately branched at intervals of 2–10 cm, without proliferations except following damage, blades linear or increasing in width above, often slightly narrowed at branchings, (0.5–)1–2(–3.5) cm broad, apices broadly rounded, with a central midrib which is slight above and prominent below with stupose hairs, without lateral veins, wing often denuded below. Structure of wing 4–7 cells thick at margin, 4–5 cells thick generally, and the midrib 8–15(–20) cells thick; cortical cells 25–50 µm across in surface view, L/B 1–2. Hair tufts dense, scattered, hairs arising from a compact group of cells, becoming sunk within the cortex, readily lost, 16–22 µm in diameter.

Reproduction. Sporangia densely scattered between midrib and margin (rarely on the midrib) with a very narrow sterile marginal zone, derived from cortical cells and remaining sunken within the cortex, with a laterally elongate stalk cell; sporangia subspherical to ovoid, 80–120 µm in diameter, irregularly tetrahedrally divided. Oogonial sori unknown. Antheridial sori small, scattered, angular and irregular in shape, derived from cortical cells and lying within the thallus, (l00–)200–500 µm across; antheridia 40–60 µmlong and 20–30 µm in diameter.

Distribution. From the Houtman Abrolhos Is., W. Aust., around southern Australia and Tas., to Port Jackson, N.S.W.

Habitat. D. muelleri is the commonest species of Dictyopteris on southern Australian coasts, being frequent in pools on rough-water coasts as well as to depths of 37 m.

[After Womersley, Mar. Benthic Fl. Southern Australia II: 227 (1987)]