Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Dicranemataceae
Thallus erect, subdichotomously branched, cartilaginous, branches compressed, apices rounded, base stoloniferous, epilithic. Structure multiaxial, with a narrow central medulla of elongate cells containing yellow refractive material, and a broad pseudoparenchymatous cortex of larger inner cells, linked by secondary pit-connections and also direct cell fusions, and a small-celled outer cortex.
Reproduction: Sexual thalli monoecious; non-procarpic. Carpogonial branches 3-celled, straight, borne on mid cortical cells with an adjacent cortical cell acting as the auxiliary cell; fusion cell small, linked to adjacent vegetative cells and producing gonimoblast filaments radially, forming a placenta from which surface-directed, parallel, slender filaments each cut off terminally 1–3 carposporangia. Cystocarps swollen, subterminal on one side of the branch which then ceases growth; pericarp thick, with a wide ostiole. Spermatangia in isolated sunken clusters among the outer cortical cells.
Tetrasporangia scattered in surface cortical layers near broader branch tips, zonately divided.
Life history triphasic with isomorphic gametophytes and tetrasporophytes.
Type species: P. australis J. Agardh 1892: 102.
Taxonomic notes: Peltasta (see Kraft 1977b, p. 235) is a monospecific southern Australian genus, differing from Dicranema in the compressed branches, stoloniferous base, central medullary layer of cells with refractive material, and in the orientation of the carposporophyte towards the branch surface.
AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.
KRAFT, G.T. (1977b). Studies of marine algae in the lesser-known families of the Gigartinales (Rhodophyta). H. The Dicranemaceae. Aust. J. Bot. 25, 219–267.
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