Classical and molecular cytogenetics of Ponerinae ants reveal evolutionary and taxonomic insights

Eleven species of Ponerinae ants belonging to six distinct genera from the Amazon and Atlantic rainforests were characterized by karyotype, distribution of ribosomal genes, microsatellites (GA)_n, and telomeric sequences (TTAGG)_n. This is the first study mapping microsatellites in Ponerinae ants. The karyotypes ranged from 2n = 12 to 2n = 94. Colonies of Neoponera verenae from the Amazon (n = 31) and Atlantic (2n = 40) rainforests reinforce the hypothesis of a species complex within this taxon. Neoponera globularia workers had a 2n = 21 karyotype, including an unpaired, large metacentric chromosome. Neoponera unidentata workers had 2n = 12 chromosomes, all metacentric, or 2n = 13 chromosomes, with two acrocentric and one unpaired metacentric chromosome. The rearrangements involved are discussed using telomeric (TTAGG)_n data. All the analyzed species had a single pair of rDNA clusters mostly located in the pericentromeric region. The distribution of (GA)_n microsatellites contrasted with that of AT-rich chromatin and supported the occurrence of chromosome fissions and the subsequent expansion of constitutive heterochromatin in Ponerinae, in addition to inversions in some species. The chromosomal rearrangements discussed herein contribute to our understanding of the mechanisms underlying the karyotypic evolution of Ponerinae. This study underscores the importance of cytogenetics in unraveling the taxonomic characteristics of complex groups.