Comparative study of the chromosome karyotypes of two species of grasshoppers in Megaulacobothrus Caudell (Orthoptera: Acridoidea)

The chromosome karyotypes of Chorthippus (Megaulacobothrus) aethalinus (Zubovsky) and Ch. (M.) chinensis Tarbinsky were compared. Results show that the chromosome numbers of the two species fit 2n (♂) = 17 = 16 + XO, in which three pairs of autosomal and sex chromosomes were terminal chromosomes, and the other five pairs of autosomes were metacentric chromosomes. These are diagnosis characters for Chorthippus. However, these two species can be distinguished by the different chromosome formula (CF) and the relative length (RL). The CF in Ch. (M.) aethalinus is K (2n, ♂) = 6m + 11t = 6L + 6M + 4S + XO, whereas that of Ch. (M.) chinensis is K (2n, ♂) = 6m + 11t = 6L + 8M + 2S + XO. In addition, we also found that the relative lengths of sex chromosomes in the two species were different from each other. The sex-chromosome of Ch. (M.) aethalinus is located at the fifth position and its relative length is 8.33% whereas that of Ch. (M.) chinensis is at the eighth position and its relative length is 5.53%. These results show that significantly different genetic features exist for the two species of Chorthippus.