Intra-varietal variability and genetic relationships among the homonymic East Adriatic olive ( Olea europaea L.) varieties

•Clonal diversity and genetic relationships among olive varieties from Slovenia, Croatia and Montenegro.•Significant differences in level of intra-varietal diversity of olives grown along East Adriatic coast.•Confirmation of international synonymy and homonymy.•New knowledge on olive spreading, selection and propagation process in the East Adriatic region in the past.