Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Nemaliales – Family Galaxauraceae
Thallus (gametophyte) erect, 3–7 cm high, subdichotomously branched, firm to brittle, surface smooth, with terete, often jointed, branches. Structure multiaxial, with an apical depression developing a medulla of branched, elongate, filaments and a cortex 3–4 cells thick, with inward large cells grading to smaller outer cortical cells. Calcification present within the cortex. Rhodoplasts campanulate.
Tetrasporophyte (in T. cylindrica) minute, filamentous, branched.
Reproduction: Gametophyte monoecious or dioecious. Carpogonial branches 3-celled, the hypogynous cell with 3–4 sterile branches and the basal cell producing a distinct involucre around the carposporophyte. Gonimoblast filaments arising directly from the fertilized carpogonium and growing towards the surface of the plant and laterally, partially or completely lining the involucre, producing terminal carposporangia. Cystocarp urceolate to subspherical, ostiolate, lying within the outer medulla. Spermatangia borne in conceptacles, terminal or lateral on inwardly directed filaments.
Tetrasporophytes with cruciately divided tetrasporangia borne terminally or laterally (Magruder 1984).
Life history triphasic with heteromorphic gametophyte and sporophyte.
Type species: T. cylindrica (Ellis & Solander) Huisman & Borowitzka 1990: 164.
Taxonomic notes: Tricleocarpa was recently segregated from Galaxaura on the basis of its well-developed sterile involucre arising from the basal cell of the carpogonial branch and its minute filamentous tetrasporophyte (Huisman & Borowitzka 1990, p. 164). The genus includes two species widely distributed in tropical and subtropical waters, with only T. cylindrica reaching as far south as Hamelin Bay on the coast of Western Australia.
HUISMAN, J.M. & BOROWITZKA, M.A. (1990). A revision of the Australian species of Galaxaura (Rhodophyta, Galaxauraceae), with a description of Tricleocarpa gen. nov. Phycologia 29, 150–172.
MAGRUDER, W.H. (1984). Reproduction and life history of the red alga Galaxaura oblongata (Nemaliales, Galaxauraceae). J. Phycol. 20, 402–409.
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.
State Herbarium of South Australia