We wish to bring attention to the following correction to Ramirez et al. (2012). Fig. 2 contains two mislabelled population clusters. As such, there are two clusters labelled seven and two clusters labelled six. In fact, the pale green cluster with red border should read cluster three, not six. The pale blue cluster should read cluster four, not seven. This error was typographical and does not influence any of the results or conclusions of our work. A corrected version of Fig. 2 is shown here.