Heterochromatic markers obtained by C-banding on metaphase plates of A. lacustris (a, d, g), A. fasciatus (b), A. schubarti (e), H. anisitsi (h) and hybrids A. lacustris × A. fasciatus (c), A. lacustris x A. schubarti (f) and A. lacustris × H. anisitsi (i) after C-banding. The arrows indicate heterochromatic blocks. The chromosomes number of A. lacustris and H. anisitsi hybrid is 2N = 51, the metaphase plate of A. lacustris and H. anisitsi hybrid (i) contains a heterochromatic chromosome (arrowhead). Scale bar: 5µm.