Cytogenetic Studies in the Genera Pheidole and Tetramorium (Hymenoptera, Formicidae, Myrmicinae)

SUMMARY

In this paper we report Pheidole pallidula with a chromosome number n=10 (6Sm + 4M) and Tetramorium hispanicum, Tetramorium semilaeve, Tetramorium caespitum, all with a chromosome number n = 14 although with some karyotypic divergences that we think are due to one pericentric inversion and tandem growth of constitutive heterochromatin. We apply the C-banding and the nucleolar organizing regions (NORs) location techniques. Generally, these species present almost one heterochromatic band with paracentromeric location. We detected a differential activity between the existing NORs sites, so we distinguish «primary NORs» and «secondary NORs».