Zethus (Zethusculus) paschoali, a new species from Piraquara, Paraná, Brazil, is described and pictures comparing it to similar species are presented.

Notes on Neotropical Eumeninae, with the description of a new species of Pachodynerus de Saussure (Hymenoptera, Vespidae). Taxonomic information on Neotropical Eumeninae is provided. A new species, Pachodynerus fessatus sp. nov. is described from southeastern São Paulo, Brazil. Additional material of Pachodynerus sericeus (Fox) was examined, representing the first further specimens after the original description and including the previously unknown male. The examination of new material of the genus Stenonartonia adds some new distribution records and shows some previously unrecorded individual variation for some species. The males of Stenonartonia guaraya Garcete-Barrett and Stenonartonia rejectoides Garcete-Barrett are described for the first time.

Agelaia Lepeletier, 1836 pertence ao grupo de vespas enxemeadoras de Polistinae, com espécies que se distribuem desde o México até o norte da Argentina. No Brasil, são encontradas 15 das 31 espécies descritas. Quatro espécies ocorrem no Rio Grande do Sul, duas das quais aqui registradas pela primeira vez para este Estado. Estas espécies são redescritas e uma chave para sua identificação é fornecida.

The genus Agelaia Lepeletier 1836 belongs to the swarming genera of the Polistinae, with species distributed from Mexico to northern Argentina. Fifteen of the 31 described species are found in Brazil. Four species occur in the State of Rio Grande do Sul, two of them recorded herein for the first time. Redescriptions and a key to these species are provided.