Wrangelia montebellensis Huisman

Scientific Description

Habit and structure. Thallus small, mostly creeping, epiphytic, spreading to 5 mm, 1–2 mm in height, pale red. Axial cells with 4 whorl branches, 2 markedly smaller and with cells about half the diameter of the others. Long whorl branches borne beside each other on axial cells, one essentially on the concave surface, the other on the convex surface. Reduced whorl branches borne in similar positions but opposite the long branches, the pairs of long and reduced branches alternating along the primary axis. Nodal cortication formed by smaller whorl branches that wrap around the primary axes. Long whorl branches 3 or 4 times dichotomously branched; terminal branches 1–3 cells long, with a terminal conical cell often of markedly smaller diameter than the subapical cell. Axial cells near apex 35–45 µm diam. [L:B c. 2], to 120 µm diam. at maturity [L:B 2–3]. Basal cells of long whorl branches 30–45 µm diam. [L:B c. 2]; median cells 25–35 µm diam. [L:B 7–8], near apices c. 25 µm diam. [L:B c. 2]. Terminal mucronate cells 8–10 µm diam. at the base [L:B 1–2]. Cells of reduced whorl branches 10–20 µm diam. [L:B 3–7].

Reproduction. Spermatangial heads spherical, 55–60 µm diam., with an involucre of 2 or 3 simple filaments. Procarps arising at apices of indeterminate lateral branches, with each fertile axial cell bearing a lateral supporting cell from which a 4-celled carpogonial branch arises. Sterile cells on supporting cell absent. Post-fertilisation development not observed. Tetrasporangia spherical, 55–65 µm diam., tetrahedrally divided, borne on much-reduced whorl branches, with 2 or 3 simple involucral filaments, each 1–2 (–3)-celled.

Distribution. Known only from the type locality and collection, Montebello Island, Western Australia.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 618 (2018)]