with the karyotype described previously for the A. frenatus. Heterochromatic segments were
visualized in a centromeric and pericentromeric position in the three species (Fig. 2). Only
two NOR sites were detected in all three species and were located in the subterminal portion
on the short arm of the 2nd pair in A. saxatilis, in a telomeric position on the short arm in one
element of pair 9 and in another one of pair 16 in M. chrysurus and on the short arm of the
acrocentric 19th pair in A. frenatus (Fig. 3).