DNA CONTENT AND HETEROCHROMATIN VARIATION IN SPECIES OF BELOSTOMA (HETEROPTERA, BELOSTOMATIDAE)

The chromosome complement of Belostoma bifoveolatum, B. dentatum, B. elegans, and B. martini were analyzed by C-banding and DNA content. The four species share a similar karyotype with 26 + X1X2Y chromosomes (male) and an equilocal distribution of C-bands at telomeric regions. The relative amount of C-banded material varies between 24% in B. martini to approximately 59% in the other three species. The DNA content differs significantly among all of them, and no clear correlation is found between DNA content and C-positive heterochromatin. The karyotype variation detected in this study suggests that several chromosomal changes took place during the evolution of the Belostomatidae, involving C-positive heterochromatin as well as C-negative chromatin. It is also suggested that a telomeric pattern of heterochromatin distribution is a common feature of heteropteran chromosomes, and it is probably related to their holokinetic nature.