Achiasmatic male meiosis in Heteroptera is a characteristic of the higher taxa in family level. The karyotype and male meiosis, with a particular focus on the presence or absence of chiasmata between the homologs, were studied in the water boatman species Micronecta (Dichaetonecta) scholtzi (Fieber, 1860), M. (Micronecta) poweri (Douglas et Scott, 1869) and M. (Micronecta)griseola Horvath, 1899, as well in Cymatia rogenhoferi (Fieber) and C. coleoptrata (Fabricius) (Corixoidae).

The male meiosis of Micronecta and Cymatia species studied is achiasmate and of an alignment type in males. It is suggested that achiasmatic male meiosis and lack of m-chromosomes are cytogenetic features sepa¬rating the family Micronectidae from the family Corixidae among the superfamily Corixoidea within the infraorder Nepomorpha. Cytogenetic and some morphological diagnostic characters separating Cymatia Flor from the rest of Corixidae are discussed. It seems plausible that achiasmatic male meiosis has emerged in Heteroptera more than once during their evolution and can be used for understanding the relationships in the superfamily Corixoidea and infraorder Nepomorpha as a whole.

This study was financially supported by the grant from the Russian Science Foundation no. 14-14-00541.