Repetitive DNA represents an important driver of sex chromosome differentiation. Yet repetitive sequences tend to be misrepresented or overlooked in genomic studies. We analysed repetitive landscape of sex chromosomes in several populations of a turquoise killifish Nothobranchius furzeri and its sister species N. kadleci (Teleostei: Nothobranchiidae), representatives of African annual killifishes with high rate of karyotype and sex chromosome evolution. We combined bioinformatic analyses of repeatome with molecular cytogenetic techniques such as comparative genomic hybridization,...