The genetic distances (Dxy) between groups of the genus Simocephalus based on the COI gene.

1–20 indicate groups of Simocephalus: 1, Simocephalus cf. vetulus from China and Taiwan; 2, S. vetulus from Europe; 3, Simocephalus cf. vetulus from Europe; 4, S. vetuloides from China; 5, S. beianensis from China; 6, S. sp. from North America; 7, S. cf. punctatus from North America; 8, S. cf. mixtus from North America; 9, S. himalayensis from China; 10, S. cf. congener from Europe; 11, S. congener from Europe; 12, S. himalayensis microdus from China; 13, S. exspinosus from Europe; 14, S. cf. exspinosus from Europe; 15, S. sibiricus from China; 16, S.sp = S. serrulatus form Taiwan in Young et al. 2012; 17, S. heilongjiangensis from China and Taiwan; 18, S. serrulatus from North America, China and Europe; 19, Daphnia cf. similoides from China (outgroup); 20, Diaphanosoma dubium from Taiwan (outgroup).Intra-group and inter-group genetic distances of the 20 groups involved 132 nucleotide sequences. The standard deviations (SD) are shown in the upper diagonal of the matrix and the right column. Analyses were conducted using the Kimura 2-parameter model.The genetic distances (Dxy) between groups of the genus Simocephalus based on the COI gene.