African freshwater eel species (Anguilla spp.) identification through DNA barcoding

Freshwater eels (Anguilla spp.) have a long and complex catadromous life cycle. This unique feature, coupled with difficulty in separating species based on morphology, makes them complex targets for conservation. In this study we evaluated the utility of DNA barcoding using cytochrome oxidase I (COI) to delimit the four species of African eels found in the western Indian Ocean region. We collected 76 individual fin clips from the four eel species (A. mossambica, n = 51; A. marmorata, n = 17; A. bengalensis, n = 6; A. bicolor, n = 2) in the rivers of KwaZulu-Natal, South Africa, in 2016-18. Phylogenetic analysis of the COI sequences recovered all four species as monophyletic. Barcoding gap analyses were performed and there was no found overlap in inter- and intraspecific genetic distances. Consequently, the use of COI barcoding as an identification tool was found to be reliable for identifying African eels to the species level, which suggests that this marker should be included in future environmental DNA or metabarcoding studies.