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Order Gelidiales

Family Gelidiaceae

Pterocladiella caespitosa (Kylin) Santelices 1998: 242

Plants bright purplish red, up to about 30 mm high, tufted, comprising a stoloniferous basal system bearing many soft flexuous upright axes. Prostrate axes cylindrical to subcylindrical, attached at intervals by tufts of rhizoids, up to 1 mm in diameter; upright axes sometimes unbranched, otherwise somewhat irregularly branched or with groups of branches arising near each other and giving an almost umbellate appearance, often with a series of small bladelets arising distichously in distal parts; branches flattened towards apices, blades up to about 1 mm wide and 200 µm thick. Branches often appear to regrow from grazed or damaged tips. Cortex of 3 pigmented layers, outer cell diameters 10-15 µm, increasing centripetally; medulla of 4-5 layers of larger colourless cells (to about 18 µm diameter), medulla in flattened blades up to 8 layers; rhizines present in medulla of thicker parts of blades but absent from some parts of prostrate axes and from upper (younger) regions of blades.

Tetrasporangia in sori covering all but margins of expanded ends of erect branches, tetrasporangia in young sori in chevron-shaped rows. Cystocarps single in distal bladelets, with gonimoblast attached to cystocarp floor and carposporangia in chains: single ostiole.

Collections, ecology and regional distribution

Recorded from Hluleka to northern Kwazulu-Natal (45-58). Known only from the lower eulittoral zone, forming tufts rather than extensive turfs.

World distribution: Also known from Mozambique, Kenya, Australia (Silva et al. 1996) and Seychelles (Santelices 1998).

Type locality: Isipingo Beach, near Durban (Silva et al. 1996).

Note: this species is described and illustrated in detail ( as Gelidium caespitosum Kylin) by Norris (1992). DNA analysis confirmed the identity of South African material (Tronchin 2003).


Pterocladiella caespitosa, specimens from Mabibi, KwaZulu-Natal (BOL).

Pterocladiella caespitosa, specimen from Mabibi, KwaZulu-Natal (BOL).

Pterocladiella caespitosa, cross section of thallus (re-drawn from Norris 1992, Fig 4F).


References Pterocladiella caespitosa

Norris RE 1992. The marine red algae of Natal, South Africa: Order Gelidiales (Rhodophyta). Memoirs of the Botanical Survey of South Africa 61: 43 pages.

Santelices, B. 1998. Taxonomic review of the species of Pterocladia (Gelidiales, Rhodophyta). Journal of Applied Phycology 10: 237-252.

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.

Tronchin, E.M. 2003. The systematics, biology and distribution of the Gelidiaceae (Rhodophyta) of South Africa and related taxa. Ph D thesis, Department of Botany, University of Cape Town, 214 + xv 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 19 April 2024.