Griffithsia inversa Huisman

Scientific Description

Habit and structure. Thallus erect from limited prostrate axes, to 15 mm tall, pink to red. Prostrate axes mainly dichotomously branched, occasionally trichotomous, attached by multicellular filaments terminating in digitate pads, with large cylindrical cells 200–300 µm diam. [L:B 3–5]. Erect axes dichotomously branched every 1–4 cells, with cylindrical cells to 300–500 µm diam. [L:B 2.5–3.5] tapering distally, the upper cells 70–150 µm diam. [L:B 6–8].

Reproduction. Tetrasporangia spherical to pyriform, tetrahedrally divided, 50–60 µm diam., pedicellate, with 2 or 3 sporangia per pedicel, arising in dense clusters initially distal but eventually covering modified subapical cells. Fertile axial cells narrower and shorter [L:B c. 1] than the subtending cell which becomes broader distally. Apical cell of tetrasporangial branches bearing 5 or 6 single-celled medial involucral branches, these curving proximally and forming a cap over the sporangia, the entire structure (apical cell and involucre) eventually becoming hyaline, the sporangia therefore appearing apical and non-involucrate.

Distribution. Known only from South Scott Reef, Western Australia.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 606 (2018)]