(a) Haplotype networks for the 6 nuclear genes: transcriptomal gene fusion protein (TigA, 33 isolates), heat shock protein 90 (HSP90, 36 isolates), enolase (36 isolates), tryptophan biosynthesis gene 1 (trp, 28 isolates), internal transcribed spacer (ITS, 37 isolates) and the beta tubulin gene (btub, 32 isolates). (b) Haplotype network of the mitochondrial gene cytochrome C oxidase subunit I (cox I, 33 isolates). Each circle represents a different haplotype, small grey circles represent unsampled, intermediate, haplotypes and colors represent the affiliation to a certain population. Color code: light green – Belgium, white – Czech Republic, purple – Finland, grey – France, green – Germany, turquois – Hungary, dark blue – Italy, orange – Netherlands, mauve – Slovenia, light blue – Serbia, red – Switzerland, pink – Turkey, and yellow – USA.