South African Seaweeds

Order Bangiales

Family Bangiaceae

Genus Porphyra C. Agardh

Gametophyte thalli bladed, membranous and monostromatic. Blades lanceolate, rosette (umbilicate) or orbicular and ranging in size from a few mm to more than a metre (only to about 30 cm on the south coast). Gametophyte phase alternating with a conchocelis-phase: a shell-boring microscopic stage that germinates into filaments. Porphyra can be monoecious, dioecious or androdioecious (hermaphrodites) and is able to reproduce sexually or asexually (in both the bladed and conchocelis-phase), via various types of spore. Modes of reproduction may vary among species and may even differ within a single species found in different localities.

Porphyra is widely distributed in temperate regions worldwide and is one of 15 genera belonging to the order Bangiales. This genus previously contained species cultivated for the multibillion dollar (USD) nori industry, but these species have been reassigned to another genus following a molecular taxonomic revision of the Bangiales (Sutherland et al., 2011). In fact, a large majority of species that were originally assigned to the genus Porphyra are now assigned to new or resurrected genera.

Porphyra currently consists of a number of species that are based on morphological species concepts (Guiry MD, in Guiry & Guiry, 2017), most of which remain to be assessed using molecular data. P. capensis Kützing 1843 is one of the species of Porphyra that has been verified using morphological, life-history and molecular data. This morphologically variably and widespread spread was shown to comprise of multiple molecular species (Jones et al., 2004; Reddy et al., 2018). These molecular species can be regarded as two endemic cryptic species groups. The first is a species-rich and genetically diverse P. capensis complex comprising eight morphologically cryptic and largely sympatric species along the west coast of South Africa (Benguela Marine Province). The second is a pair of cryptic sibling species along the south coast of South Africa (Agulhas Marine Province) that are morphologically distinct from the P. capensis complex on the west coast. The more widely distributed and abundant of the cryptic species pair along the south coast of South Africa is in the process of being described as a new species (Reddy et al., in prep).

Although the two cryptic species groups are morphologically distinct from one another, species within each of the groups are not.

Key to south coast species

1a Blade thickness greater than 60 µm, 1-2 chloroplast(s) per cell, cells appear ovoid in cross section of the thallus, trichogynes absent	P. capensis complex (Cryptic species complex)
1b Blade thickness less than 60 µm, 1 chloroplast per cell, cells appear elliptical in cross section of the thallus, trichogynes present	P. species duo (Cryptic species pair)

Note: Species belonging to the P. capensis complex are commonly dioecious, thallus rosette or lanceolate, generally darker and larger than the cryptic species duo and commonly occur along the west coast of South Africa (Cape Agulhas to Port Nolloth). The cryptic species duo are monocieous (however, their life-histories require further study), thalli generally delicate and light in colour, dwarf rosette, deeply laciniate (star-shaped), poorly adherent to herbarium sheets and are restricted to the south coast of South Africa (Port Alfred to Mossel Bay).

References Porphyra

M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2017. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 21 November 2017.

Jones, W.A., Griffin, N.J., Nelson, W.T, Farr, T.J. & Broom, J.E. 2004. Phylogenetic diversity in South African Porphyra (Bangiales, Rhodophyta) determined by nuclear SSU sequence analyses. European Journal of Phycology 39: 197-211.

Reddy, M.M., De Clerck, O., Anderson, R.J., Leliaert, F. & Bolton, J.J. 2018. A rosette by any other name: Species diversity in the Bangiales (Rhodophyta) along the South African coast. European Journal of Phycology, https://doi.org/10.1080/09670262.2017.1376256.

Sutherland, J.E., Lindstrom, S.C., Nelson, W.A., Brodie, J., Lynch, M.D., Hwang, M.S., Choi, H.-G., Miyata, M., Kikuchi, N., Oliveira, M.C., Farr, T., Neefus, C., Mols-Mortensen, A. Milstein, D. & Müller, K.M. 2011. A new look at an ancient order: generic revision of the Bangiales (Rhodophyta). Journal of Phycology 47(5): 1131-1151.

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 18 November 2024.