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Order Gigartinales

Family Gigartinaceae

Gigartina pistillata (S.G. Gmelin) Stackhouse 1809: 74

Thalli usually dark- to blackish-red but sometimes green or greenish-purple, terete basally to slightly flattened distally, irregularly dichotomously branched, up to 20 cm tall. Holdfast a small disc or compound disc giving rise to many uprights; axes 2-3 mm diameter, tough, branched more frequently and sometimes very densely towards distal end. Structure multiaxial; medulla of thick-walled filaments surrounded by narrow layer of cortical filaments in a mucilaginous matrix. Female thalli with fairly numerous small lateral branches that come off mainly in two opposite rows running down opposite sides of the flattened distal axes. Lateral branches bearing one to more than 5 globose cystocarps (2-3 mm diameter), each with a distinct ostiole. Tetrasporangial sori immersed in inner cortex along margins of distal axes, forming dark longitudinal swellings; tetrasporangia cruciately divided, 25-40 µm long and 10-25 µm wide.

Distribution and ecology

Found from False Bay eastwards to the Port Alfred area (17-39), in the sublittoral fringe and shallow sublittoral.

World distribution: Found on the warm temperate coasts of Europe and at the Canary Islands.

Type locality: Unknown, for information on type see Dixon and Irvine 1977: 239.

Note: This species was retained in the genus Gigartina by Hommersand et al. (1993, 1994).

 


Gigartina pistillata, green form from Three Sisters, near Port Alfred.


Gigartina pistillata, habit. Reproduced from Stegenga et al. (1997).

 

References Gigartina pistillata

Dixon, P. S. and L. M. Irvine. 1977. Seaweeds of the British Isles. I. Rhodophyta 1. Introduction, Nemaliales, Gigartinales. London: British Museum (Natural History), 252 pp.

Hommersand, M. H., Fredericq, S. & D. W. Freshwater. 1994. Phylogenetic systematics and biogeography of the Gigartinaceae (Gigartinales, Rhodophyta) based on the sequence analysis of rbcL. Botanica Marina 37: 193-203.

Hommersand, M. H., Guiry, M. D., Fredericq, S. & G. L. Leister. 1993. New perspectives in the taxonomy of the Gigartinaceae (Gigartinales, Rhodophyta). Hydrobiologia 260/261: 105-120.

Stegenga, H., Bolton, J.J. & R. J. Anderson. 1997. Seaweeds of the South African west coast. Contributions from the Bolus Herbarium 18: 655 pp.

Stackhouse, J. 1809. Tentamen Marino-Cryptogamicum. Mémoires de la Société Impériale des Naturalistes de Moscou, 2: 50-97.

 

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, http://southafrseaweeds.uct.ac.za; Accessed on 18 December 2018.