DNA barcoding in the red algal order Gelidiales: comparison of COI with rbc La nd verification of the "barcoding gap"

M itochondria-encoded COI and plastid-encoded rbc Ls equences were used to assist with the identification or "barcoding" of av ariety of red algal species. The rbc Ll ocus has been extensively analyzed within the Gelidiales and general levels of intraspecific and interspecific sequence divergences are established. Complementary COI and rbc Ld ata sets were compared to explore the utility of COI for Gelidiales species identification and verify the presence of ab arcoding gap between closely related species. There was no difference between the two loci in the clustering of specimens into species, but the COI sequences were more variable than rbc La nd exhibited al arger barcoding gap between closely related sister species. These results indicate that COI barcoding is au seful tool for the molecular assisted identification of Gelidiales species, especially in cases of closely related species where the more conserved rbc Lm ay be uninformative. The presence of cryptic species within the widely distributed taxon, Pterocladiella caerulescens was also revealed, and taxonomic changes are proposed including the description of Pterocladiella australafricanensis sp. nov. COI /D NA barcoding /G elidiales / Gelidium / Pterocladiella / Pterocladiella austral- africanensis / rbcL