Genetic differentiation among ten populations of the genus Neoplecostomus (Teleostei: Loricariidae) from the upper Paraná River basin

► The analyses of the data allowed the identification of 10 loci and 23 alleles. ► The average proportion of polymorphic loci was 31% for all populations. ► The values of expected heterozygosity ranged from 0 to 0.242 among ten populations. ► Values of expected heterozygosity indicate an excess of homozygotes. ► Genetic identity values among ten populations indicate they belong to different species.