Comparative karyotype analysis of grasshoppers in the genus Oxya (Orthoptera, Catantopidae) by differential staining techniques

The chromosomes of 4 species of grasshopper in the genus Oxya were analyzed by conventional and five differential-staining methods. All 4 species had a chromosome complement of 2n=22+XX(female)/XO(male), with very similar karyotypes. Both O. hyla intricata and O. japonica japonica had acrocentric chromosomes with minute short arms, while the chromosomes of O. chinensis formosana and O. yezoensis were almost all telocentric. In all 4 species, a secondary constriction (SC) was detected at a proximal site in chromosome 8, which had the same staining properties (positive for C- and CMA-banding; negative for G- and QM-banding) in all 4 species. Our C-banding analysis revealed that the short arms of O. hyla intricata and O. japonica japonica consisted of C-heterochromatin. The 4 species yielded species-specific patterns of C-bands, and there appeared to be a close relationship between O. chinensis formosana and O. yezoensis, as suggested by the polymorphism of the distal C-bands of chromosome 2. In all 4 species of Oxya, Ag-NORs were detected on the centromeric regions of all the chromosomes, but not detected on the SC of chromosome 8. The karyosystematic relationships among the 4 species are discussed on the basis of the results of differential staining.