Please cite this article as: Lawton, S.P., Lim, R.M., Dukes, J.P., Kett, S.M., Cook, R.T., Walker, A.J., Kirk, R.S., Unravelling the riddle of Radix: DNA barcoding for species identification of freshwater snail intermediate hosts of zoonotic digeneans and estimating their inter-population evolutionary relationships, Infection, Genetics and Evolution (2015), doi: http://dx.doi.org/10. 1016/j.meegid.2015.07.021 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. and ITS2 sequences, identified populations of Radix auricularia and R. balthica from specimens originally morphologically identified as R. peregra from the UK. Assessment of cox1 and ITS2 as species identification markers showed that, although both markers differentiated species, cox1 possessed greater molecular diversity and higher phylogenetic resolution. Cox1 also proved useful for gaining insights into the evolutionary relationships of Radix species populations. Phylogenetic analysis and haplotype networks of cox1 indicated that Radix auricularia appeared to have invaded the UK several times; some haplotypes forming a distinct UK specific clade, whilst others are more akin to those found on mainlandEurope. This was in contrast to relationships between R. balthica populations, which had low molecular diversity and no distinct UK specific haplotypes, suggesting recent and multiple invasions from mainland Europe. Molecular techniques therefore appear to be crucial for distinguishing Radix spp., particularly using cox1. This barcoding marker also enables the population biology of Radix spp. to be explored, and is invaluable for monitoring the epidemiology of fluke diseases especially in the light of emerging diseases and food security.