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Order Gelidiales

Family Gelidiaceae

Gelidium abbottiorum R. Norris 1990: 41, figs 2,3,7,8.

Plants erect, to about 20 (-30) cm tall, stiff and wiry, purplish red to pale at the tips; holdfast fibrous and bearing several to many uprights; axes terete to subterete, up to 1 mm in diameter; branching alternate to irregular, sparse basally to more regular distally; branches at wide angles, straight or curved, often reflexed especially if unbranched, terminal branches narrower than axis (to 250 µm in diameter). Anatomy of darkly pigmented outer cortical cells up to 8 µm in diameter grading into larger ovate or angular inner cortical cells up to 25 µm in diameter and attached by long arms to medullary cells; medullary cells with thick walls with filamentous appearance due to long extensions; refractive rhizines concentrated in bundles in inner cortex and scattered in medulla. Fertile branches terminal, often geniculate; tetrasporangia in sori; cystocarps biloculate, usually near apex of branchlets, which may have short sterile apical protuberance; male branchlets similar to tetrasporangial branchlets with sori of dense, elongated spermatangial cells.

Collections, ecology and regional distribution

Found on wave-exposed shores in the mid to lower eulittoral zone, sublittoral fringe and tidal pools. Recorded from Cape Hangklip (130 km west of Agulhas) to Kosi Bay in northern Kwazulu-Natal. (22-58).

World distribution: South African endemic.

Type locality: Widenham, Kwazulu-Natal (Norris 1992).

Note: This species was previously known as Gelidium amansii. G. abbottiorum is distinguishable from G. pteridifolium by its scruffy appearance and irregular branching (branches in the latter species are regular, imparting a fern-like appearance).

 


G. abbottiorum, Double Mouth.


G. abbottiorum, branching detail.


G. abbottiorum, xs through cortex and part of medulla.


G. abbottiorum, thallus apex. Reproduced from Stegenga et al. (1997).

 

References Gelidium abbottiorum

Norris RE 1990. A critique on the taxonomy of an important agarophyte, Gelidium amansii. Japanese Journal of Phycology (Sôrui) 38: 35-42.

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.

Stegenga, H., Bolton, J.J. and 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, http://southafrseaweeds.uct.ac.za; Accessed on 25 September 2018.