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Order Ceramiales

Family Callithamniaceae

Callithamnion Lyngbye

Plants filamentous, alternately branched, with one lateral per segment; thalli polystichous or more or less complanate; filaments ecorticate or in older parts of the plant with a rhizoidal cortex. Tetrasporangia sessile on uiltimate and penultimate branchlets, tetrahedrally divided. Spermatangial heads pyramidal or hemiglobose, one to four heads sessile on cells of ultimate branch systems. Female reproductive structures developing on a subterminal intercalary cell, involving a supporting cell with a carpogonial filament, and a second fertile pericentral cell; carposporohyte developing from two auxiliary cells and forming typical twin gonimolobes, without involucral filaments.

Note: According to Guiry & Guiry (2015), “Feldmann-Mazoyer (1941) erected the genus Aglaothamnion for species with uninucleate cells, zig-zag carpogonial branches and lobed groups of carposporangia, and recircumscribed Callithamnion. Aglaothamnion is now sometimes regarded as a synonym of Callithamnion with insufficient evidence for separate evolutionary lines of development”. We follow Stegenga et al. (1997) and Stegenga (1988) in ascribing our taxa to Callithamnion.

Key to the species

1a. Asexual plants with polysporangia

Callithamnion collabens

1b. Asexual plants with tetrasporangia, occasionally bisporangia


2a. Plants spongy, the apices frequently with short spines; plants with a greenish sheen

Callithamnion stuposum

2b. Plants of more open construction, not bearing truly spinous ramuli; colour red


3a. Plants mainly branched in one plane


3b. Plants polystichously branched, or distichously in terminal branches


4a. Cells throughout the thallus 1-2 times as long as broad

Callithamnion tripinnatum

4b. Cells up to more than four times as long as broad. Species only found in estuaries with fresh water influence

C. sp. 2

5a. Apical cells of the ramuli extremely short, much smaller than the subapical cells

Callithamnion granulatum

5b. Apical cells of the ramuli not much smaller than the subapical cells


6a. Terminal branch systems often complanate

Callithamnion hookeri

6b. Terminal branch systems polystichous


7a. Cells of the main axis up to twice as long as broad

Callithamnion cordatum

7b. Cells of the main axes relatively longer

C. sp. 1

References Callithamnion

Feldmann-Mazoyer, G. 1941 '1940'. Recherches sur les Céramiacées de la Méditerranée occidentale. pp. 1-510, 191 figs, pls I-IV. Alger: Imprimerie Minerva.

M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 25 September 2015.

Stegenga H. 1988. Notes on Ceramiaceae (Rhodophyta) from the eastern Cape Province, South Africa I. New records and remarks on morphology. Blumea 33: 371-393.

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 19 April 2024.