Wikipedia
Parancistrocerus is a rather large genus of potter wasps whose distribution spans the Nearctic, Palearctic, Oriental and Neotropical regions. Their species are notable for having a smopth depression acting as an acarinarium at the base of the second metasomal tergum and hidden under the first metasomal tergum. This acarinarium serves as shelter for symbiotic deuteronymphs of mites in the family Winterschmitiidae. Most of the species bear a transverse carina on the first metasomal tergum and the whole body of many neotropical species have a faint submetallic luster. A pair of medial pits on the anterior face of the pronotum and the expansion of the tegulae put this genus close to the genus Stenodynerus and many species of both genera are somewhat difficult to assignate to their respective genus.