The South American genera of the Cimbicidae are reviewed. Five genera and nine species are recognized. Redescriptions of all genera and an identification key to all species are provided. All species are illustrated, including both sexes and aberrant specimens when relevant. The South American Cimbicidae are grouped in the subfamily Pachylostictinae, but there is substantial morphological divergence at the genus level. This and the isolated geographic and phylogenetic position relative to the other subfamilies of Cimbicidae indicates that the Pachylostictinae have evolved in isolation for a substantial amount of time. Host plant records are known for only one species, Pseudopachylosticta subflavata, which is mainly found in the Chacoan subregion. The distribution of the remaining species falls almost exclusively within the range of the Parana subregion forest provinces, a biome that has been much reduced by human activity in the past half millennium. It is likely that these rarely collected wasps are threatened by habitat degradation.
‘Symphyta’, Tenthredinoidea, neotropics, identification, distribution.