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Order Ceramiales

Family Rhodomelaceae

Herposiphonia secunda f. tenella (C.Agardh) M.J.Wynne 1984: 173, 175, figs. 11, 12

Plants prostrate with erect axes up to about 5 mm tall; branches produced from almost all segments of indeterminate axes. Prostrate axes attached by up to three rhizoids per segment; rhizoids may become digitate; apices of main axes curved upwards, often overtopped by apices of young determinate laterals that curl forward. Indeterminate branches alternate; determinate branches in dorsal row, arising from (almost) every segment in a series of three determinate/ one indeterminate lateral. Determinate branches comprising usually about 30 (but up to 50) segments, incurved when young, becoming straight when mature, usually narrower than prostrate branches, often with a few subapical or apical trichoblasts. Segments cylindrical, with (8-) 10-12 pericentral cells, up to 35-70 (-80) µm in diameter, 1-3 times as long as broad, basal cell with four pericentral cells. Tetrasporangia one per segment, in rectilinear series. Antheridial stands in adaxial series or arranged radially and subapically. Cystocarps one per branchlet, rarely seen, somewhat urn-shaped, ca. 350 (high) X 300 µm (wide), usually on 4th to 6th segment.

Collections ecology and regional distribution

Recorded from Cape Agulhas to Park Rynie in Kwazulu-Natal (22-50). A common component of short algal turfs on the south coast, also found in “limpet gardens” and growing on various larger algae and sessile animals such as Pyura and mussels.

World distribution: Widespread in warm temperate and tropical seas.

Note: Jaasund (1976) records 12-16 pericentral cells in H. secunda f. tenella from Tanzania.

 


Herposiphonia secunda forma tenella showing general structure (stained slide).


Herposiphonia secunda forma tenella showing general structure (stained slide).


Herposiphonia secunda forma tenella, trichoblasts on determinate laterals (stained slide).


Herposiphonia secunda forma tenella, antheridial stands (stained slide).


Herposiphonia secunda forma tenella. 1. Habit. 2. Apex of prostrate filament. 3. Mature erect filaments (note well developed trichoblasts). Reproduced from Stegenga et al. (1997).

 

References Herposiphonia secunda f. tenella

Jaasund, E. 1976. Seaweeds in Tanzania: A field guide. Tromsø: University of Tromsø. 166 pp.

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

Wynne, M.J. 1984. Notes on Herposiphonia (Rhodomelaceae, Rhodophyta) in South Africa, with a description of a new species. Cryptogamie, Algologie 5: 167-177, 12 figs.

 

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 20 September 2018.