title: Achiasmate male meiosis in two Cymatia species (Hemiptera, Heteroptera, Corixidae).
abstract: 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 Cymatia rogenhoferi (Fieber) and Cymatia coleoptrata (Fabricius) (Corixidae, Cymatiainae). It is shown that the species have 2n = 33 (28A+2m+X1X2Y) and 2n = 24 (20A+2m+XY) respectively, post-reduction of sex chromosomes, and achiasmate meiosis of an alignment type in males. Cytogenetic and some morphological diagnostic characters separating Cymatia Flor from the rest of Corixidae are discussed.
authors.affiliation: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 1 Tsar Osvoboditel, Sofia 1000, Bulgaria.
authors.forename: Desislava
authors.initials: D
authors.lastname: Stoianova
authors.affiliation: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 1 Tsar Osvoboditel, Sofia 1000, Bulgaria.
authors.forename: Snejana
authors.initials: S
authors.lastname: Grozeva
authors.affiliation: National museum of Natural History, Bulgarian Academy of Sciences, 1 Tsar Osvoboditel, Sofia 1000, Bulgaria.
authors.forename: Nikolay
authors.initials: N
authors.lastname: Simov
authors.affiliation: Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, Russia.
authors.forename: Valentina
authors.initials: V
authors.lastname: Kuznetsova
keywords: Corixoidea; Karyotype; Nepomorpha; m-chromosomes; morphology; sex chromosome post-reduction; spermatocyte meiosis