Contribution of Cytogenetics to the Debate on the Paraphyly ofPachycondylaspp. (Hymenoptera, Formicidae, Ponerinae)

Abstract

We present evidence of the paraphyly of the ant genusPachycondylaresulting from our cytogenetic studies on 29 populations in 18 species from Brazil and French Guyana. It is likely that karyotypes with a large number of chromosomes and comprising mostly small acrocentric chromosomes in species within thePachycondyla stricto sensugroup resulted from a succession of centric fission events. On the other hand, karyotypes with a small chromosome number comprising mostly metacentric chromosomes are also interpreted as little derived and tend to undergo centric fission. The karyotypes of the groupNeoponeraare more heterogeneous and probably undergo successive cycles of rearrangements tending to increase the chromosome number by centric fission. Theapicalisandverenaecomplexes form two probable sister groups that evolved independently due to centric fissions (verenae) and pericentric inversions (apicalis). Our results reveal the karyotype diversity in the genus and reinforce the hypothesis on the paraphyly ofPachycondyla.