1. 2Seaweed Unit, Department of Agriculture, Forestry and Fisheries
DIVERSITY OF THE SOUTH AFRICAN LAURENCIA COMPLEX (RHODOPHYTA): MOLECULAR EVIDENCE FOR NEW SPECIES & GENERA RECORDS
Caitlynne Francis1, John J. Bolton1, Lydiane Mattio1 & Robert J. Anderson1,2
1Ma-Re Institute & Department of Biological Sciences, University of Cape Town
2Seaweed Unit, Department of Agriculture, Forestry and Fisheries
INTRODUCTION
MATERIALS & METHODS
Literature lists ten species in the Laurencia complex of red seaweeds from South Africa, all ascribed to the genus Laurencia Lamouroux (Laurencia sensu stricto)1,2. The genus is ecologically important on the coastlines of South Africa and the diversity of the complex in South Africa has not been reassessed following the numerous taxonomic changes in this group in the last two decades.
Using molecular methods allied with detailed morphological study, we investigate the relationships among South African Laurencia taxa & the recently described genera of this complex.
The taxonomy of this group in South Africa was examined using recent collections. Algal DNA was extracted using the Qiagen Plant MiniKit™ under manufacturer's instructions.
Methods include a molecular phylogenetic analysis of plastid rbcL gene sequences generated in this study (88 specimens) and downloaded from GenBank, using Bayesian Inference (Model: GTR + I + G) in MrBayes v3.2.2 on CIPRES3 (Figure 1), and morphological characters, including the number of corps en cerise if present (Figure 2: Images G & H).
RESULTS
Laurencia s.s.
Laurenciella
Yuzurua
Palisada
Chondrophycus
Osmundea A B C
1.5mm
1.5mm D E F
0.5mm G H
Figure 2: 5 new species in Laurencia s.s.: A) L. dehooopiensis, B) L. sodwaniensis, C) L. multiclavata, D) L. digitata, E) L. dichotoma.
F) L. stegengae – a new combination for South African Laurencia
G&H) Numbers of corps en cerise used to distinguish between the morphologically similar L. cf. elata & L. flexuosa, respectively.
DISCUSSION
The molecular analysis supported the monophyly of the six genera of the Laurencia complex with high posterior probabilities (PP=1.00). 17 morphotypes were identified: 13 in the genus Laurencia sensu stricto, among which Nine correspond to Laurencia species currently recognised from South Africa and one each correspond to species in the genera Palisada, Chondrophycus and Laurenciella.
The 5 remaining morphotypes in Laurencia sensu stricto did not match any descriptions in the genus Laurencia and represent new species: Laurencia dehoopiensis sp. nov., L. dichotoma sp. nov., L. digitata sp. nov., L. multiclavata sp. nov. & L. sodwaniensis sp. nov.
The diversity is likely greater, with six additional unidentified clades found in this molecular investigation.
Figure 1: Phylogeny of the Laurencia complex determined from a Bayesian inference of the plastid rbcL gene (model: GTR + I + G). PP≥0.90 shown.
PP = Posterior Probability
These findings place South Africa alongside Australia in having one of the most diverse floras of this group in the world.
Refences:
1.De Clerck, O., Bolton, J.J., Anderson, R.J. & Coppejans, E Guide to the seaweeds of KwaZulu-Natal. Scripta Botanica Belgica 33.
National Botanic Garden of Belgium, VLIZ: Flanders Marine Institute & Flemish Community, pp. 1 – 242
2. Stegenga, H., Bolton, J.J. & Anderson, R.J Seaweeds of the South African West Coast. Contributions from the Bolus Herbarium Number 18