In our samples, the most intense DNA amplification, leading to large C-positive regions besides the large regions enriched by rDNA or rDNA and telomeric repeats, appears to have taken place during the chromosomal evolution of P. schultei. Large C-bands are present in the pericentric regions of all chromosomes apart from a pair of large metacentric autosomes and the X chromosome. Some of them form whole chromosome arms in biarmed chromosomes; in other biarmed chromosomes, they are even present in both arms, whereas in acrocentrics, C-bands were only observed in pericentric regions. In P. schultei, the chromosome morphology after C-banding makes the identification of centromeres difficult for many chromosomes. However, in DNA amplification forming C-bands, a few copies of rDNA genes or fragments homologous to them were involved and visualized by FISH (Figure 6b).