FISH with 18S and 5S rDNA probes in meiotic cells from males. The probe, type of sex-chromosome system and name of species are indicated in each figure. Chromosomes with positive signals and sex chromosomes are indicated. Note the presence of pericentromeric sites for 18S rDNA on the X-chromosomes of Ch. chiquitensis and E. brevicerci and on the neo-X1 chromosomes of D. lilloanus and D. schrottkyi, as well as the 5S rDNA on the sex bivalent neo-XY chromosome of E. minor and in multiple sites on the neo-Y chromosome in D. lilloanus and D. schrottkyi. Bar = 5 μm.