Comparative cytogenetics of three Zoraptera species as a basis for understanding chromosomal evolution in Polyneoptera insects.

Zoraptera (also called "angel insects") is one of the most unexplored insect orders. However, it holds promise for understanding the evolution of insect karyotypes and genome organization given its status as an early branching group of Polyneoptera and Pterygota (winged insects) during the Paleozoic. Here, we provide karyotype descriptions of three Zorapteran species: (2n♂; ♀ = 42; 42), (2n♂; ♀ = 43; 44) and (2n♂; ♀ = 36; 36). These species represent two of the four recently recognized Zorapteran subfamilies. Contrary to an earlier suggestion that Zoraptera has holocentric chromosomes, we found karyotypes that were always monocentric. Interestingly, we detected both X0 () and XY (, ) sex chromosome systems. In addition to conventional karyotype descriptions, we applied fluorescent hybridization for the first time in Zoraptera to map karyotype distributions of 18S rDNA, histone H3 genes, telomeres and (CAG) and (GATA) microsatellites. This study provides a foundation for cytogenetic research in Zoraptera.