2013 年 78 巻 4 号 p. 411-415
The diploid chromosome number and male meiosis in Ectomocoris atrox, E. tibialis, E. melanopterus, and Peirates bicolor (Heteroptera: Reduviidae: Peiratinae) have been described. Three species of Ectomocoris have 2n=23=20A+X1X2Y, while Peirates bicolor has 2n=23=20A+X1X2Y. One pair of autosomes is distinctly large in all the species of Ectomocoris, while Peirates bicolor possesses three pairs of large bivalents suggesting autosomal fusion. In Peirates bicolor with XY mechanism, X is larger than the X components of E. atrox, E. tibialis, and E. melanopterus with X1X2Y mechanism, indicating fragmentation of X to be the mode of origin of X multiplicity. In the presently studied four species, the general course of meiosis is typical of Reduviidae. Sex chromosomes remain condensed and distantly placed during the diffuse stage. Single terminal chiasma per bivalent is seen in all except Ectomocoris atrox. At metaphase I, chromosomes arrange in a regular pattern in all the species, which is strikingly different from the typical random arrangement pattern previously reported in Reduviidae.