Abstract
Thallus upright, bright green, siphonous, to 7–10 cm in height, with several terete, primary axes growing from a rhizoidal plexus. Primary axes 0.8–1 mm diam, tapering slightly to apices, simple or generally dichotomously or subdichotomously branched every 7–20 mm, with constrictions at base of branches, densely radially covered by lateral ramuli to near the base. Branches (primary axes plus ramuli) 5–8 mm diam. Ramuli straight or inwardly curved, simple, terete, 4–5 mm long, constricted at base, inflated and rounded, to 70–85 µm diam., tapering to 55–60 µm diam., then 50 µm diam. mid ramulus and 35 µm diam. at the rounded apices. Plastids subspherical to ellipsoidal. 2–4 µm diam., without an obvious pyrenoid. Mature gametangia borne 1 or 2 per ramulus, close to base, initially with an open connection to the ramulus but this eventually occluded. Spent gametangia often present as empty walls, in addition to mature gametangia. Gametangia 100–120 µm long, 65–85 µm diam., ellipsoidal or obovoid, with an apical papilla. (Figure 1)
