Craspedocarpus ramentaceus (C.Agardh) Min-Thein & Womersley

Scientific Description

Habit and structure. Thallus erect, light to medium red, fading to grey-red, 10–20 cm high, membranous, complanately and irregularly laterally branched, main branches flat, 0.5–2 cm broad and (100–)150–300 µm thick, tapering to 1–2 mm broad with an irregular fringe of (usually) prominent marginal proliferations usually 2–5 mm long and 0.3–1 mm broad, apices acute and often fimbriate. Holdfast discoid; epilithic or epiphytic. Structure uniaxial, forming an alternately pinnate vein system (visible when stained) with a rhizoidal sheath developing around the axial filament and a thin filamentous medulla, with a cortex 1–2 cells thick, inner cells ovoid and 50–100 µm in diameter, with well-developed rosettes becoming 2–3(–4) cells broad, cells 4–8 µm across. Rhodoplasts discoid in rosette cells, usually ribbon shaped and crowded in inner cells.

Reproduction. Sexual thalli dioecious; procarpic. Carpogonial branches 3-celled, borne on inner cortical cells near the edges of small, flat marginal proliferations, similar to those of C. blepharicarpus, with the carposporophyte having several central cells and radiating gonimoblast filaments with terminal chains of ovoid carposporangia 18–25 µm in diameter, together with some sterile filaments fusing with pericarp cells and with the inner nutritive tissue. Cystocarps protuberant, on the edge of the marginal proliferations (rarely on main branches), 500–1000 µm across, with a cortical pericarp, non-ostiolate. Spermatangia cut off from rosette cells via initials. Tetrasporangia scattered in the cortex of marginal proliferations, ovoid, 16–28 µm in diameter, zonately divided.

Distribution.Safety Bay, W. Aust., to Snowy R. mouth, Vic., and around Tas.

Habitat. C. ramentaceus is found in deep-water on open coasts or where there is strong current flow.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 425–427 (1994)]