Ceramium pseudoaffine Huisman

Scientific Description

Habit and structure. Thallus with indeterminate prostrate axes attached by pigmented multicellular holdfasts arising as extensions from periaxial cells, and simple to once- or twice-branched erect axes to 1.5 mm tall, with straight to slightly curved apices. Axial cells 20–30 µm diam. (including wall) [L:B 1–5 (shorter near apices)]; nodes to 36 µm diam. Periaxial cells 3, this number most obvious in lower nodes; in upper nodes 1 (–2) lateral pseudoperiaxial cells cut off from periaxial cells, the node then ringed by 4 (–5) cells. Periaxial cells undivided or obliquely cutting off an acropetal cell from one corner, rarely a second from the opposite corner. Basipetal development absent.

Reproduction. Tetrasporangia arising laterally on periaxial cells, 1 per node, although some nodes appearing to have a second tetrasporangial initial arising opposite the first (i.e. on the other lateral face of the periaxial cell), spherical to pyriform, tetrahedrally divided, naked, 40–50 µm diam., 50–60 µm long. Other reproductive structures not seen.

Distribution. Known only from Barrow Island and from the Dampier Archipelago, north-western Australia.

Habitat. Epiphytic in the intertidal and subtidal.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 401–403 (2018)]