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Order Ceramiales

Family Rhodomelaceae

Colacopsis velutina (M.T.Martin & M.A.Pocock) R.E.Norris 1988: 233

Plants parasitic on Rhodomelopsis africana, with an endophytic portion comprising monosiphonous filaments penetrating the host tissue and an external portion comprising a pustule of pseudoparenchymatous tissue with radiating polysiphonous filaments bearing reproductive structures. Tetrasporiferous filaments up to 500 µm long, with short monosiphonous base and polysiphonous segments bearing tetrasporangia; tetrasporangial segments with 5 pericentral cells of which 3 remain sterile and 2 become fertile, each producing a tetrasporangium and 2 cover cells. Sporangia tetrahedrally divided, about 20 µm in diameter, approximately opposite in segment, generally in vertical rows but sometimes decussate. Cystocarps globose with a narrow lateral ostiole and multilayered pericarp.

Collections, ecology and regional distribution

Recorded from Brandfontein, just west of Agulhas, to East London (22-41). Known only as a parasite of Rhodomelopsis africana.

World distribution: Probably a South African endemic: the record of this species from Kerguelen Island is questioned by Norris (1988).

Type locality: Three Sisters, Eastern Cape (Norris 1988).

Note: see Martin and Pocock (1953) for) detailed illustrations and descriptions of this species (as Melanocolax velutina). These authors distinguish the pustules of Colacopsis from the white “galls” that can be found on Rhodomelopsis: The pustules are reported to be softer than the galls, to have a velvety surface, and usually to be lower down on the host plants.


Colacopsis velutina on Rhodomelopsis (Bol 148948 rehydrated specimen).

Colacopsis velutina on Rhodomelopsis - detail (Bol 148948 rehydrated specimen).

Colacopsis velutina. 1. Cross section of tetrasporophyte on the host Rhodomelopsis africana. 2. Tetrasporiferous filaments (note monosiphonous base). Reproduced from Stegenga et al. (1997).


References Colacopsis

Martin, M.T. & Pocock, M.A. 1953. South African parasitic Florideae and their hosts. 2. Some South African parasitic Florideae. Journal of the Linnean Society of London, Botany 55: 48-64, 7 figs, pls 10-12.

Norris, R.E. 1988. A review of Colacopsis and Melanocolax, red algal parasites on South African Rhodomelaceae (Rhodophyta). British Phycological Journal 23: 229-237, 12 figs, 1 table.

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 26 February 2024.