Abstract Despite being mostly solitary and nesting in cavities, Zethus is more widely known by its few representatives that build external aerial nests. Here, nests of Zethus nodosus collected in the first decades of the twentieth century in surrounding areas of the Museu de Zoologia da Universidade de São Paulo are described and ponderations about the absence of more recent material are made. cavities Here made

Abstract Zethus is the most speciose genus among vespid wasps and has become even larger after the inclusion of closely related taxa as subgenera after a morphological phylogenetic analysis. Despite being taxonomically reviewed in the past, the Neotropical diversity of the group demonstrates potential for even further growth. A new species of Zethus (Zethoides) Fox, 1899 is herein described, being the fifth one to be described in this subgenus after the great taxonomic revision of the genus in the New World.

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