Deep phylogeographic divergence and cytonuclear discordance in the grasshopper Oedaleus decorus

► Mitochondrial DNA revealed a surprisingly deep genetic split in Oedaleus decorus. ► Population genetic analyses of microsatellites and mtDNA support high divergence. ► Colonization of Europe and contact between lineages in the Alps is post-glacial. ► Combined molecular data showed cytonuclear discordance in Northern Italy.