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Order Corallinales

Family Corallinaceae

Sub-family Corallinoideae

Amphiroa J.V. Lamouroux

Thalli with a crustose base and dichotomously branched cylindrical or compressed upright axes. Conceptacles distributed over most of the surface of the intergenicula, often several to many per segment. Intergenicula with wings in some species. There are 49 species currently recognized worldwide, and the genus is common in tropical and subtropical regions (Guiry & Guiry 2014). Six species are recorded from the South African south coast. Four of these were included in a recent DNA barcoding study of South African geniculate corallines (Kogame et al. 2017).

Key to south coast Amphiroa

1 a. Genicula very distinct, blackish-purple, 1-2 mm long in older parts of thallus

A. ephedraea

1 b. Genicula less than 1 mm long in older parts of thallus, indistinct or invisible


2 a. Axes flattened, genicula bearing distinct, pinkish, calcified nodules

A. bowerbankii

2 b. Axes cylindrical or flattened, no calcified nodules on genicula


3 a. Genicula hidden by aprons at upper and lower ends of intergenicula, axes cylindrical

A. capensis

3 b. Genicula not hidden by aprons, axes cylindrical or flattened


4 a. Axes flattened, intergenicula 3-10 (-15) mm long, 0.5-3 (-4) mm wide

A. anceps

4 b. Axes cylindrical to slightly compressed, intergenicula no longer than 5 mm


5 a. Axes cylindrical to slightly compressed, intergenicula 0.5-1 mm wide, genicula visible but inconspicuous

A. beauvoisii

5 b. Axes cylindrical, plants fine, intergenicula less than about 0.5 mm diameter, genicula barely visible or invisible

A. rigida

References Amphiroa

Guiry, M.D. & Guiry, G.M. 2014. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched May 2014.

Kogame, K., Uwai, S., Anderson, RJ., Choi, H-G. & J.J. Bolton. 2017. DNA barcoding of South African geniculate coralline red algae (Corallinales, Rhodophyta). South African Journal of Botany 108: 337-341.


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 02 March 2024.