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Order Ceramiales

Family Dasyaceae

Heterosiphonia arenaria Kylin 1938: 17, pl. 6: fig. 17

Plants partly prostrate, entangled with other algae; attached by rhizoids developing on modified pseudolaterals. Erect parts up to 5 cm tall, pinnate; segments of main axis uncorticated, with 8-10 pericentral cells surrounding central cell. Pseudolaterals alternate, arising at intervals of 3-4 segments, several times distichously branched at intervals of 2 or 3 segments; proximal segments of pseudoaterals polysiphonous, ultimate ramifications monosiphonous, apical ramuli ca. 10-15 cells long, more or less incurved. Tetrasporangial stichidia borne on polysiphonous part of the pseudolaterals; stichidia conical, up to 800 x 250 µm; segments with (in general) six pericentral cells and tetrasporangia; sporangia globose, ca. 70 µm in diameter, tetrahedrally divided, pericentral cells with two groups of two cover cells. Sexual reproductive structures not seen.

Collections, ecology and regional distribution

Recorded from Swartklip in False Bay to Cape Vidal area in KwaZulu-Natal (18-56). Found in algal turfs in the sublittoral fringe.

World distribution: South African endemic.

Type locality: Humewood Beach, Port Elizabeth (Silva et al. 1996).

Note: Stegenga et al. (1997) record the occurrence (De Hoop and the Eastern Cape) of a similar entity with “a thicker main axis with some development of cortication”. A De Hoop specimen is illustrated here (as Heterosiphonia sp. De Hoop D163).


Heterosiphonia arenaria, dissecting microscope photograph, scale bar ca. 500 µm.

Heterosiphonia arenaria, branch detail.

Heterosiphonia arenaria, tetrasporangial stichidium (stained slide).

Heterosiphonia arenaria. 1. Detail of main axis and pseudolaterals. 2. Immature tetrasporangial stichidium. 3. Pseudolaterals with tetrasporangial stichidia. Reproduced from Stegenga et al. (1997).

Heterosiphonia sp De Hoop (D 163), dissecting microscope photograph.

Heterosiphonia sp (De Hoop specimen D 163).

Heterosiphonia sp branch detail (De Hoop specimen D 163).

Heterosiphonia sp, transverse section of distal axis, showing axial cell and pericentral cells (De Hoop specimen).


References Heterosiphonia arenaria

Kylin, H. 1938. Verzeichnis einiger Rhodophyceen von Südafrika. Acta Universitatis Lundensis 34(8): 1-26, 10 figs, 8 plates.

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


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 24 May 2024.