Table S1 Values of the first three discrimination measures of variables used in the multiple correspondence analysis.

Table S2 Morphological divergence between populations of G. balcanicus. Lower diagonal: results of the Kruskal–Wallis nonparametric anova post hoc multiple comparisons of multiple correspondence analysis object scores. D1, D2, D3 indicates dimensions which differentiated populations at p < 0.05. Upper diagonal: morphological distances between centroids of each population.

Table S3 P-values for between-population comparisons of the level of within-population morphological variance in G. balcanicus (anova, F12,229 = 12.13, p < 0.001; unequal N HSD Tukey test for independent samples). Shaded boxes indicate p < 0.05.

Table S4 Mean molecular distances (below diagonal) and standard errors (above diagonal) between populations of G. balcanicus. a: p-distance, b: Kimura 2-parameter distance.

Table S5 Mean distance (below diagonal) and standard errors (above diagonal) between population of G. balcanicus from locus typicus (BAL) and other morphologically well-defined Gammarus species. BOS: G. bosniacus, PLJ: G. pljakici, SAL: G. salemaai, SKE: G. cf. sketi, MAC: G. macedonicus, PUL: G. pulex, FOS: G. cf. fossarum, LAC: G. lacustris, VAR: G. varsoviensis, LEO: G. leopoliensis, ROE: G. roeselii, STO: G. stojicevici. a: p-distance, b: Kimura 2-parameter distance.

Please note: Wiley Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.