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Order Ceramiales

Family Rhodomelaceae


Herposiphonia didymosporangia Stegenga and Kemperman 1987: 133

Plants prostrate. Indeterminate axes attached by unicellular rhizoids that may become digitate, up to five rhizoids per segment. Determinate laterals stout, blunt, cylindrical, up to 200 µm wide and 1500 µm long, comprising about 18 segments, each about one third as long as broad. Six pericentral cells in basal segment, increasing up to 18 in mid region of axes. Tetrasporangia 70-80 µm in diameter, two per segment, in two rectilinear series in all except the basal and most distal segments of determinate laterals. Sexual reproduction unknown.

Collections, ecology and regional distribution

Collected from St James (False Bay), Brandfontein (just west of Cape Agulhas), De Hoop and Tsitsikamma (17-32). Epilithic and on articulated corallines in the lower eulittoral.

World distribution: also recorded from Luderitz, Namibia (Stegenga et al. 1997).

Type locality: St James, False Bay, South Africa (Silva et al. 1996).

Note: see also Stegenga et al. (1997).


Herposiphonia didymosporangia, structure of thallus (stained slide, isotype material, BOL).

Herposiphonia didymosporangia, apex of male thallus with antheridial stands (stained slide, isotype material, BOL).

Herposiphonia didymosporangia, detail of part of determinate lateral (stained slide, isotype material, BOL).

Herposiphonia didymosporangia, detail of tetrasporangia (stained slide, isotype material, BOL).

Herposiphonia didymosporangia. 1. Detail of main axis with determinate and indeterminate laterals. 2. Apex of tetrasporiferous branchlet (after Stegenga and Kemperman 1987). Reproduced from Stegenga et al. (1997).


References Herposiphonia didymosporangia

Silva, P.C., Basson, P.W. & Moe, R.L. 1996. Catalogue of the benthic marine algae of the Indian Ocean. University of California Publications in Botany 79: 1-1259.

Stegenga, H., Bolton, J.J. & R. J. Anderson. 1997. Seaweeds of the South African west coast. Contributions from the Bolus Herbarium 18: 655 pp.

Stegenga, H. & Kemperman, T.C.M. 1987. A new species of Herposiphonia (Rhodomelaceae, Rhodophyta) from South Africa. Acta Botanica Neerlandica 36: 133-137, 7 figs.


Cite this record as:

Anderson RJ, Stegenga H, Bolton JJ. 2016. Seaweeds of the South African South Coast.
World Wide Web electronic publication, University of Cape Town,; Accessed on 26 February 2024.