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Order Gigartinales

Family Phacelocarpaceae

Phacelocarpus oligacanthus Kützing 1868: 25, pl. 71, a,b

Thalli dark red, erect, up to 25 cm or longer, attached by discoid holdfasts. Axes terete, 2-4 mm in diameter (wider at base in old plants), bearing many short lateral branches that arise irregularly. Thallus serrate, with many short branchlets/spines arranged in regular radial pattern; cortication increasing with age of thallus or part of thallus, so that basal parts of thalli or older thalli may lack spines and have smooth but uneven texture; branch apices crowded with spines. Structure of branches uniaxial, in cross-section axial cell distinct and much larger than surrounding medullary cells; cortex of anticlinal rows of cells decreasing very noticeably in diameter towards periphery, outer cortical cells very small (2-3 µm diameter) and darkly pigmented. Dioecious; reproductive structures formed on spiny lateral branchlets. Tetrasporangia zonately divided, arranged around the sides of deep, open channels in the branchlets. Mature cystocarpic branchlets resemble swollen vegetative branchlets with well-developed teeth; carposporangia released though slits. Spermatangia borne in short, spiny, lateral branchlets.

Collections, ecology and regional distribution

Recorded from Cape Agulhas to near Umkomaas on the KwaZulu-Natal coast (22-50), in the lower eulittoral and sublitoral zones (De Clerck et al. 2005).

World distribution: South African endemic.

Type locality: “Cap Bona Spei” (Silva et al. 1996).

Note: For details of morphology and reproductive structure see Searles (1968).


Phacelocarpus oligacanthus, Mkambati (BOL).

Phacelocarpus oligacanthus, Mkambati , detail of spiny branchlets (herbarium specimen, BOL).


References Phacelocarpus oligacanthus

De Clerck, O., J.J. Bolton, R.J. Anderson and E. Coppejans, 2005. Guide to the Seaweeds of Kwazulu-Natal. National Botanic Garden of Belgium, Brussels (Scripta Botanica Belgica), 294 pp.

Kützing F.T.1868. Tabulae Phycologicae….Nordhausen. Vol 18 (1) + 35 pp., 100 pls.

Searles R.B. 1968. Morphological studies of red algae of the order Gigartinales. University of California Publications in Botany 43: 1-100. 

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.


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.