Adelophycus corneus (J.Agardh) Kraft

Scientific Description

Habit and structure. Thallus dark red-brown, 8–16 cm high, cartilaginous with softer branch tips, much branched subdichotomously at intervals of (2–)5–10(–15) mm, branches linear or slightly constricted every 1–3 mm, slightly compressed, 1–2(–3) mm broad. Holdfast discoid-conical, 1–4 mm across, with a short terete stipe 1–3 mm in diameter; epilithic. Structure multiaxial, developing a moderately dense medulla of entangled filaments and a cortex of more-or-less anticlinal filaments in discrete branch systems, lax in the inner cortex and becoming compact in the outer cortex where the cells become isodiametric, in 3–5-celled rows, 3–4 µm in diameter; pyriform gland cells prominent in the mid to outer cortex, 12–18 µm in diameter; some inner cortical and outer medullary cells produce rhizoidal filaments. Rhodoplasts discoid, becoming elongate in inner cells.

Reproduction. Sexual thalli dioecious. Carpogonial branches borne on outer ends of inner cortical cells, 3–4 cells long, directed outwards, with a single post-fertilization connecting filament which branches. Auxiliary cells subterminal in long, unbranched rhizoidal filaments borne on outer medullary cells, terminating in the inner cortex. Gonimoblast initial arising from the connecting filament adjacent to the auxiliary cell, forming a single (often lobed) cluster of gonimoblast filaments directed mainly inwards, with all cells of the carposporophyte forming subspherical carposporangia 20–25 µm in diameter. Spermatangia cut off from outer cortical cells near branch tips, elongate, producing ovoid spermatia 2–3 µm in diameter. Tetrasporophytes unknown.

Distribution. Cockburn Sound, W. Aust., to Point Lonsdale, Vic.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 272–273 (1994)]