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Order Ceramiales

Family Ceramiaceae

Antithamnionella Lyle

Plants filamentous, uncorticated, usually partly prostrate, partly erect: thalli differentiated into long indeterminate axes and short determinate whorl-branches. Whorl-branches occurring in numbers from 1 to 6 per segment, the number usually variable within the species. Gland cells more or less abundant, found on unmodified cells of the whorl-branches. Tetrasporangia formed on proximal cells of the whorl-branches, sessile or pedicellate, tetrahedrally divided. Spermatangial heads small, shortly cylindrical, developing on proximal cells of whorl-branches. Procarp formed on the basal cell of a reduced, two-celled whorl-branch, closely below the apex of erect indeterminate axes; main axes discontinuing growth with the production of a carposporophyte. Carposporophytes with a varying number of gonimolobes, without an involucre. Of the 25 currently recognised species (Guiry & Guiry 2015), five are recorded on the south coast.

Key to the species

1a. Plants with two (more rarely three) laterals per cell

Antithamnionella spirographidis

1b. Plants regularly with three or more laterals per cell


2a. Determinate laterals within one whorl strongly dissimilar

Antithamnionella tormentosa

2b. Determinate laterals in a whorl of about similar development.


3a. Determinate laterals usually unbranched, or with one (to three) laterals


3b. Determinate laterals usually with alternating laterals

Antithamnionella sp.

4a. Determinate laterals usually with prominent, almost globose gland cells on the second cell

Antithamnionella verticillata

4b. Determinate laterals with flattened gland cells higher up

Antithamnionella ternifolia

References Antithamnionella

Guiry, M.D. & Guiry, G.M. 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 16 September 2015.

Stegenga, H., Bolton, J.J. & 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,; Accessed on 26 February 2024.