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Order Ectocarpales

Family Scytosiphonaceae

Petalonia Derbès & Solier

Thalli erect, simple blades with small holdfast and short stipe, a few to about 20 cm tall. Cortex of 1-2 layers of small, pigmented cells underlain by outer medulla of large colourless cells and inner medulla either of large colourless cells or loose hyphae (species specific); pheaophycean hair tufts present. Plurilocular sporangia in continuous sori on large areas of blades, unilocular sporangia unknown in our material, reported in some species to be borne on alternating crustose phase. Five species are currently recognized worldwide (Guiry & Guiry 2014). South African members of the genus include the entity previously known as Endarachne binghamiae (e.g. see Stegenga et al. 1997), now considered to be a species of Petalonia (Boo 2010). Two species of Petalonia are recorded on the south coast, but some records must be treated with caution because of the superficial similarity between the species.


Key to species

1a. Blades 200-300 µm thick at centre, central medulla of loose network of hyphae

P. binghamiae

1b. Blades to 120  µm thick at centre, central medulla of compact parenchymatous cells

P. fascia


References Petalonia

Boo, S.-M. 2010. Scytosiphonaceae, Petrospongiaceae. In: Algal flora of Korea. Volume 2, Number 1. Heterokontophyta: Phaeophyceae: Ectocarpales. Marine brown algae I. (Kim, H.-S. & Boo, S.-M. Eds), pp. [155]-185. Incheon: National Institute of Biological Resources.

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


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.