Gelidiella acerosa (Forsskål) J. Feldmann & G. Hamel 1934

    Thalli brownish-black to yellowish green with well-developed stoloniferous holdfast, 3–8 cm long and 0.5-1mm broad. Stolons form tufts or clumps of tough and wiry, flexible axes, attached by peg-like haptera or terminating in multicellular rhizoids. Erect axes cylindrical in basal parts; most often pinnately and distichously branched, more rarely radial or unilaterally branched. Main axes frequently curved, arcuate; pinnae short, 2–7 mm long, perpendicularly placed on the axis and gradually shorter towards the branch apices; branches sometimes anatomizing, predominant in prostrate parts; apices acute, hairs often present.

    Internal structure consisting of a cortex of small, ovoid, darkly-pigmented cells up to 10 layers, 8-18 μm long and 3-11 μm broad; centrally grading into larger, obovoid to irregularly shaped, thin walled medullary cells; rhizines consistently absent.