Wrangelia dampierensis Huisman

Scientific Description

Habit and structure. Thallus to 10 cm tall, tufted, richly branched, light red, but the central axes accumulating debris and appearing slightly yellow-brown. Structure with 4 unequal whorl branches per axial cell, the composition variable, but generally with 1 long branch, 2 intermediate and 1 or 2 remaining reduced and producing branched nodal cortical filaments that encircle the axial cell but do not form a dense cortical layer. Nodal cortical filaments also arising from basal cells of other determinate lateral branches. Indeterminate branches 1 per axial cell, on primary axes in a radial or subdistichous pattern, not forming a pyramidal outline, on lateral branches mostly secund (particularly near branch apices), with the tips of the bearing branch curved towards the side with indeterminate branches. Cells of primary axes 50–60 µm diam. near apices [L:B 1.5–2.5], broadening gradually to 250–300 µm diam. near the base [L:B c. 2]. Cortical filaments arising from the basal cells of whorl branches, markedly narrower than bearing cells. Elongate attachment rhizoids produced from basal cells of whorl branches. Whorl branches 3 or 4 times dichotomously divided, divaricate, with ultimate branches 2–4 cells long and terminating in a short mucronate cell; basal cells 25–40 µm diam. [L:B c. 1.5]; median cells 20–30 µm diam. [L:B 8–10]; mucronate cells 7–12 µm diam. at the cell base [L:B c. 2].

Reproduction. Tetrasporangia arising on compound fertile whorl branches, with numerous sporangia at various stages of maturity, to 70 µm diam., with 1–3 simple 2- or 3-celled involucral filaments arising from the subtending cell. Other reproductive structures not observed.

Distribution. This species is known only from Malus Island, Dampier Archipelago, Western Australia.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 613–616 (2018)]