Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Polyidaceae
Thallus much branched, with flat, ovate to elongate, intemodal calcified segments connected by uncalcified nodes, branching from the apex of internodes, attached by small discoid holdfasts. Structure multiaxial, with a densely filamentous medulla and a cortex of anticlinal rows of subspherical to elongate cells; calcification within the cortex.
Reproduction: All reproductive organs formed in uncalcified, superficial, nemathecia on the surface of segments. Sexual thalli dioecious; carpogonial branches 3–8 cells long, erect, straight, lying between paraphyses; auxiliary cell branches 3–12 cells long, similar but separate from carpogonial branches, with post-fertilization fusion of the carpogonium to a hypogynous cell and then by connecting filament to an auxiliary cell; gonimoblast filaments much branched, with the end cells, or most, forming carposporangia, the carposporophytes lying within the nemathecia. Spermatangia in lateral tufts from nemathecial filaments or cut off from outer cortical cells.
Tetrasporangia in shallow nemathecia, formed on outer cortical cells or on branched nemathecial filaments, irregularly zonately to cruciately divided.
Life history triphasic with isomorphic gametophytes and tetrasporophytes.
Type species: R. australis Harvey 1863: pl. 264.
Taxonomic notes: A genus of 5 species, the type from southern Australia and 4 other species from Japan (Nozawa 1963; 1970). Rhodopeltis australis was described by Harvey (1863, pl. 264) as a new genus and species, applied to the fertile nemathecia which Harvey considered a parasite on Amphiroa australis Sonder. Harvey cited "Cruoria? australis Harvey mss" in his description, apparently forgetting that he had described this in 1855a (p. 551). This earlier name (and Amphiroa australis Sonder) must give way to Harvey's use of australis as a new species in describing Rhodopeltis in 1863. Weber-van Bosse (1904, p. 104) established the genus Litharthron, based on sterile material of Amphiroa australis Sonder, and placed it in the Corallinaceae.
HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)
NOZAWA, Y. (1963). Systematic anatomy of the genus Rhodopeltis. Mem. Junshin Jun. Coll. 5, 1–48.
NOZAWA, Y. (1970). Systematic anatomy of the red algal genus Rhodopeltis. Pacif. Sci. 24, 99–133.
WEBER-VAN BOSSE, A. (1904). The Corallinaceae of the Siboga Expedition. Siboga-Expeditae, Monogr. LXI.
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