New Records of the Cleptobiotic Stingless Bee <i>Lestrimelitta Chacoana</i> from Paraguay and Northwestern Argentina (Hymenoptera: Apidae)

New records of the Chaco Region cleptobiotic stingless bee Lestrimelitta ( Lestrimelitta ) chacoana Roig-Alsina are provided from Paraguay and northwestern Argentina at the western and eastern extremes of the greater Chaco, the latter at the transition from the humid Chaco to the Atlantic Coastal Forest. Notes on character variation are provided along with images of the species, a key to species of Lestrimelitta Friese s. str ., and a key to subgenera of Lestrimelitta. The following new subgenera are established: Apiraptor subgen. n., Hyrolestris subgen. n.