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Ceramium filicula Womersley

This name is not current. Find out more information on related names.

Reference
Austral.J.Mar.Freshwater Res. 238-240; Figs 4E, F, 15A-E (1978)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Not Current

Scientific Description

Habit and structure. Thallus medium to dark red, 0.3–1(–1.5) cm high, at first with a single erect base attached by rhizoids descending from the lower segments, and later with prostrate filaments. Branching essentially complanate, alternate and 3(–5) cells apart, forming flabellate groups of laterals, usually without proliferations. Attachment by relatively massive holdfasts formed of numerous, usually tightly clumped, rhizoids originating from all the cortical cells on the underside of a node, and with the ends of the peripheral rhizoids splayed out and becoming multicellular; epiphytic on cartilaginous brown (and occasionally red) algae. Structure. Branches terete, 100–300 µm in diameter below, with the laterals 80–150 µm in diameter near their bases, tapering to 50–70 µm shortly below the straight to slightly involute apices. Axial cells L/D about 1(–1.5) throughout the thallus, with internodal spaces 0.5–1(–2) times as long as nodal bands in mature parts, shorter near the apices. Periaxial cells 6, each cutting off usually 2 cells acropetally and 2(–3) cells basipetally; the basipetal cells usually cut off only 1 (rarely 2) more cell so that basipetal chains in older parts are only 2(–3) cells long; acropetally, the derivatives cut off (1–)2(–3) cells which divide similarly twice in mid parts of the thallus and up to 4 times in older parts, with some cells being cut off in the reverse direction; the node is thus 5–6 cells long (30–70 µm) in mid parts of the thallus, and may be up to 9 cells long (80–150 µm) in older parts; the nodes have relatively straight margins and the acropetal development is always greater than the basipetal. No real outer cortex is formed, but rhizoidal cortication of the axial cells occurs near the thallus base. Fine, slender hairs occur in actively growing plants. Rhodoplasts discoid in small cells, ribbon like in larger cells.

Reproduction. Gametophytes dioecious. Carposporophytes occur on upper branches, globular, 150–300 µm across, with 3–6 relatively robust, usually slightly curved, involucral branches; carposporangia ovoid-angular, 15–30 µm across. Spermatangia covering the nodal cortex of upper branches and often reaching the apices, surrounding the branchlet or sometimes mainly adaxial. Tetrasporangia in lateral branches, opposite in the plane of branching with the fertile branchlet ovoid in section, arising acropetally from the opposite periaxial cells (often with a later formed sporangium), largely involucrate within the cortical filaments (which may be 1–2 cells longer than in vegetative parts), subspherical to ovoid, 30–50 µm across, decussately divided.

Distribution. Houtman Abrolhos, W. Aust., to Coffs Harbour, N.S.W.

Habitat. Usually growing under moderate to strong water movement, epiphytic on large brown algae.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIC: 412–415 (1998)]