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Order Ceramiales

Family Rhodomelaceae

Placophora monocarpa (Montagne) Papenfuss 1956: 73-74

Prostrate thallus dark red to blackish, forming a foliose crust up to several cm in diameter on the host, Ecklonia maxima. Vegetative structure essentially the same as that of P. binderi. Fertile filaments numerous, giving the thallus a velvety appearance; free filaments up to 5 (-10) mm long, compressed. Tetrasporangia ca 60 µm in diameter, in long straight series distal to the third to twelfth segment. Spermatangial stichidia arising in radial series on a number of subapical segments, conical, ca. 200 x 50 µm. Cystocarps usually one per erect filament, urceolate, ca. 400 x 200 µm, with narrow ostiole.

Collections, ecology and regional distribution

A common epiphyte on Ecklonia maxima, and therefore found where E. maxima occurs (1-22). Although E. maxima has recently appeared at De Hoop (24), we do not know if P. monocarpa is present there. Pocock (1953) recorded it from drift in the Port Elizabeth area, but that merely confirms the great distances travelled by floating thalli of E. maxima.

Worldwide distribution: Also known from Namibia.

Type locality: Cape of Good Hope (Silva et al. 1996).

Notes: 1. This species was previously known as Placophora eckloniae Pocock.
2 Stegenga et al (1997) record a specimen of somewhat similar gross morphology, growing on Ecklonia radiata from the Three Sisters – Port Alfred area, but note that it showed a somewhat different branching pattern and could not be identified with certainty because it was infertile.


Placophora monocarpa: stained slide preparation of west coast material with tetrasporangial filaments.

Placophora monocarpa: stained slide preparation showing detail of tetrasporangial filament .

Placophora monocarpa. 1. Apex of prostrate thallus. 2. Detail of thallus, dorsal view. Reproduced from Stegenga et al. (1997).

Placophora monocarpa. 1. Tetrasporangia. 2. Antheridial heads. 3. Cystocarp. 4. Optical section of cystocarp, showing carposporophyte. Reproduced from Stegenga et al. (1997).


References Placophora monocarpa

Papenfuss G. F. 1956: Notes on South African marine algae IV. Journal of South African Botany 22: 65-77.

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.


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.