Over more than a decade ago, COI region have been widely studied with the purpose to develop a “barcode” for species (e.g., Arnason et al., 2004; Amaral et al., 2007). However, as occurs with any new genetic tool, the barcode method still presents some limitations, such as the low availability of intraspecific variation analyses in some species (e.g., Frézal & Leblois, 2008; Mitchell, 2008). In this study, we have contributed to the knowledge of the genetic diversity of. M. novaeangliae with two novel COI sequences, extending the number of described sequences from one to three for the southern distribution range of the species,and from nine to eleven for its entire geographical distribution.The lack of a phylogeographic pattern, suggested by the network results, may be due to the low number of sequences previously described for the species and analyzed in this study. In order to develop a robust genetic tool, more analyses of COI sequences are urgently needed.