Median-joining network of 154 individuals of Chondrostoma nasus of the River Rhine basin including reference haplotypes of Chondrostoma angorense (Hap_12) and Parachondrostoma toxostoma (Hap_13). The size of the circles is proportional to the frequency of fish carrying the respective haplotype. Colours refer to the origin-sampling site. Mutational steps are represented by intermediated dashes. Black dots represent missing haplotypes.