• Aegean islands;
  • Cicadoidea;
  • France;
  • Iberian Peninsula;
  • insects;
  • microsatellites;
  • North Africa;
  • null alleles;
  • population structure

Cicada barbara (Stål) and Cicada orni L. are two Mediterranean cicadas, very similar in morphology, that produce distinct acoustic mating signals and that have partially overlapping distribution ranges in the Iberian Peninsula, occurring in sympatry in several locations. In the present study, six microsatellite loci were analysed in C. barbara, four of which were also analysed in C. orni. Geographical and temporal genetic variation in these species was studied. No evidence of hybridization was found, enabling us to infer that the isolating barriers between these species are efficient. Partitioning of geographic variation in each species, revealed the following patterns: Iberian Peninsula and Northwestern African populations of C. barbara showed higher differentiation between than within each region, supporting C. barbara subspecific taxonomy (C. barbara lusitanica in the Iberian Peninsula and C. barbara barbara in Northwestern Africa) and highlighting isolation coincident with the presence of physical barriers to gene-flow; differentiation between populations of C. orni from both sides of the Pyrenees was very low, and this mountain range may not constitute a significant barrier for the dispersal of this species; Greek populations of C. orni were found to be highly differentiated from Western European populations; and no pattern of isolation-by-distance was found in either species within the Iberian Peninsula. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 249–265.