In many ant species, newly mated queens can associate themselves with other queens to establish new colonies independent of parenthood (Hagen et al., 1988; Sasaki et al., 1996). In some cases, workers become reproductive and es-Abstract In ant taxonomy, biological studies are especially important to complete the information aiming to identify species belonging to unresolved or confused taxa. Such observations allow the inclusion of biological data with other characteristics of the determined group, something that preserved specimens in collections do not reveal, such as nesting site, foraging time, nuptial flight and especially the relationship between castes, in support of taxonomic analysis and descriptions. Here, nests of three species of the complex P. foetida were observed and collected in three Brazilian localities. Pleometrosis, secondary monogyny and cannibalism were observed for the ant P. inversa. In many ant species, newly mated queens associate with other queens to establish new colonies, independent of parenthood. In the ant genus Pachycondyla, the reproductive structure varies broadly and aggressiveness seems to be an important factor in structuring the organization and reproductive division in the colony. The occurrence of males in nests of P. inversa and P. curvinodis also allowed the description of males. The nuptial flight period was estimated to be August for P. inversa, October for P. villosa and November for P. curvinodis.