Cladophora coelothrix Kütz.

Scientific Description

Habit and structure. Thallus medium to dark green, drying brownish, forming dense turfs or cushions to several cm across and to 4 cm high, composed of a basal tangle of branched, often curved, stolon-like filaments giving rise to ascending, more-or-less erect, branch-systems. Growth largely by divisions of conspicuous apical cells, but intercalary cells may divide into shorter cells; feebly to distinctly acropetal at the apices, densely and irregularly branched with many cells (especially lower ones but often also those near the apices) producing a descending rhizoid from their basal poles, and which attach to the substrate or other filaments with a terminal coralloid holdfast; lateral branches mostly wide-angled (45° or more) arising singly (occasionally two) at or just below a cross wall, with the new wall remaining steeply inclined to the parent cell. Apical cells 60–140 µm in diameter, L/B 3–16, cylindrical with rounded ends; mid and lower thallus cells 70–220 µm in diameter, L/B 2–11; ratio of lower cell to apical cell diameters (0.6–)1–1.5(–2.5); cell walls thin in younger cells (2–4 µm), mostly 4–8 µm thick below and up to 20 µm thick in old cells.

Reproduction. By zooids developing in normal vegetative cells at or near apices of outer filaments of the cushions.

Distribution. Warm temperate to tropical Atlantic coasts of Europe, Africa and America; probably widespread in tropical and warm temperate waters. In southern Australia, from Fremantle, W. Aust., around southern Australia (not Tas.) to Moreton Bay, Qld.

Habitat. Common in shaded areas or pools near low tide level on rough-water coasts but extending into sheltered areas.

[After van den Hoek & Womersley in Womersley, Mar. Benthic Fl. Southern Australia I: 190–192 (1984)]