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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Rhodocallideae
Thallus erect, complanately much branched pinnately with irregular, alternate, indeterminate compressed branches bearing close set, alternate, short, distichous determinate branchlets. Apical cells dividing obliquely, producing 4 periaxial cells spirally and in alternating sequence, the first formed periaxial filaments becoming alternately distichous determinate branchlets from each axial cell, the second and third becoming caducous, and the fourth contributing only to the cortex. Indeterminate branches becoming heavily corticated, with an inner layer of dense rhizoidal filaments around the axial cells. Cells uninucleate.
Reproduction: Gametophytes dioecious. Procarps borne on the second and third periaxial filaments of dwarf indeterminate branches, the periaxial cell being the supporting cell, with a 4-celled carpogonial branch but without sterile cells. Auxiliary cell dividing to form a foot cell and gonimoblast initial giving 4–6 gonimolobes, with a rhizoidal involucre and an outer involucre of determinate branchlets. Spermatangia cut off from initials on the surface cortical cells.
Tetrasporangia derived directly from surface cortical cells of the determinate branchlets, tetrahedrally divided.
Type (and only) species: R. elegans Kützing 1847: 36.
Taxonomic notes: The structure and development of Rhodocallis was investigated in detail by Hommersand et al. (1998), who showed that the apical development of 4 alternately produced periaxial cells is unique in the Ceramiaceae, and the formation of spermatangia and tetrasporangia directly from cortical cells is distinctive.
References:
HOMMERSAND, M.H., WILSON, S.M. & KRAFT, G.T. (1998). Morphology and systematics of Rhodocallis elegans Kützing, Rhodocallideae, Trib. nov. (Ceramiaceae, Rhodophyta) from southeastern Australia. J. Phycol. 34, 865–879.
KÜTZING, F.T. (1847). Diagnosen and Bemerkungen zu neuen oder kritischen Algen. Bot. Zeit. 5, 1–5, 22–25, 33–38, 52–55, 164–167, 177–180, 193–198, 219–223.
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
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