Dasya elongata Sond.

Scientific Description

Habit and structure. Thallus red to brownish red, to 10 cm tall, with ocellate apices. Primary axes with polysiphonous lateral branches arising every 1–3 segments near apices, more sparse in lower portions; pseudolaterals produced on every segment in a radial pattern. Primary axes lightly corticated by basipetal filaments arising from periaxial cells, commencing 15–20 segments from the apex. Axes to 0.5 mm diam. [segment L:B c. 1], with 5 pericentral cells. Pseudolaterals 1.0–1.2 mm long, curved, proximally 5 or 6 times subdichotomously branched, including the basal cell, with 1 (–2) cells between dichotomies; ultimate branches 6–10 cells long. Basal cell of pseudolaterals 90–190 μm diam., equidimensional; suprabasal cells 85–100 μm diam., slightly rounded; subsequent cells narrowing rapidly and becoming elongate, with cells of the ultimate branches 7–10 μm diam. [L:B c. 20], hyaline. Adventitious polysiphonous branches rarely present.

Reproduction. Tetrasporangial stichidia arising on pseudolaterals as 1 branch of a lower dichotomy, lanceolate, 500–600 μm long, 150–240 μm diam., sessile or with a 1- or 2-celled pedicel, with 8–10 fertile segments and 5 or 6 tetrasporangia per segment, with 3 obloid cover cells per tetrasporangium, these forming a palisade and covering c. 50% of the tetrasporangium. Tetrasporangia spherical, 50–65 μm diam., tetrahedrally divided. Other reproductive structures not observed.

Distribution. Only reliably known from Australia.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 429–432 (2018)]