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Order Ceramiales

Family Callithamniaceae

Callithamnion sp 1 (= Callithamnion sp. in Stegenga et al. 1997, p. 402).

Plants erect, usually epiphytic, up to 1.5 cm tall on the south coast (up to 5 cm on the west coast). With a distinct main axis and numerous (often one per cell of the main axis) indeterminate laterals repeating the branching scheme of the main axis but usually much shorter. Apex hidden by young laterals. Main axis in the basal part covered with a filamentous medulla, reaching a diameter of ca. 250 µm; cells of the main axis varying in length from 1 to 4 times the diameter. Laterals of all orders polystichously arranged, the determinate branches subdichotomously ramified up to 4 times from the first cell onward. Apical cells rounded, ca. 12-17 µm in diameter, cells in non-growing portions more tapered. Tetrasporangia one or two per cell of (sub) terminal branch systems, measuring ca. 60 x 50 um, tetrahedrally divided. Spermatangial heads up to three per cell, together forming a flattened structure ca. 85 µm long and 25 µm tall. Carposporophytes with round twin gonimolobes of ca. 150 µm in diameter, the synchronously formed carposporangia up to 30 µm in diameter.

Collections, ecology and regional distribution

Recorded from the Cape Peninsula to Haga Haga (17-42).

Note: This species has been compared to C. cordatum (Stegenga et al. 1997). Both species cover almost the same stretch of the south coast; differences include the on-average longer cells in the main axis and the round gonimolobes in Callithamnion sp. 1.


Callithamnion sp.1, tetrasporangial, Morgan Bay.

Callithamnion sp.1, young carposporophyte, Morgan Bay (stained slide).

Callithamnion sp.1, view of thallus of young carposporophyte, Morgan Bay (stained slide).

Callithamnion sp.1, tetrasporangial, Morgan Bay, detail.


References Callithamnion sp.1

Stegenga, H., Bolton, J.J. & 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 02 March 2024.