COMPARATIVE A peer-reviewed open-access journal CompCytogen 9(3): 335–422General (2015) trends of chromosomal evolution in Aphidococca... 335 doi: 10.3897/CompCytogen.v9i3.4930 REVIEW ARTICLES Cytogenetics http://compcytogen.pensoft.net International Journal of Plant & Animal Cytogenetics, Karyosystematics, and Molecular Systematics General trends of chromosomal evolution in Aphidococca (Insecta, Homoptera, Aphidinea + Coccinea) Ilya A. Gavrilov-Zimin1, Andrey V. Stekolshchikov1, D.C. Gautam2 1 Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, Russia 2 Department of Bio-Sciences, Himachal Pradesh University, Shimla, India Corresponding author: Ilya A. Gavrilov-Zimin (
[email protected]) Academic editor: V. Kuznetsova | Received 20 March 2015 | Accepted 14 May 2015 | Published 9 July 2015 http://zoobank.org/A0F846CD-6AB3-4FC7-B52F-57B0697418A7 Citation: Gavrilov-Zimin IA, Stekolshchikov AV, Gautam DC (2015) General trends of chromosomal evolution in Aphidococca (Insecta, Homoptera, Aphidinea + Coccinea). Comparative Cytogenetics 9(3): 335–422. doi: 10.3897/ CompCytogen.v9i3.4930 Abstract Parallel trends of chromosomal evolution in Aphidococca are discussed, based on the catalogue of chro- mosomal numbers and genetic systems of scale insects by Gavrilov (2007) and the new catalogue for aphids provided in the present paper. To date chromosome numbers have been reported for 482 species of scale insects and for 1039 species of aphids, thus respectively comprising about 6% and 24% of the total number of species. Such characters as low modal numbers of chromosomes, heterochromatinization of part of chromosomes, production of only two sperm instead of four from each primary spermatocyte, physiological sex determination, "larval" meiosis, wide distribution of parthenogenesis and chromosomal races are considered as a result of homologous parallel changes of the initial genotype of Aphidococca ancestors.