The fossils were recovered in 1995 from outcrops of Turonian age[3][4] strata in the White Oaks Pit, Middlesex County, New Jersey by Paul Nascimbene and subsequently embedded in blocks of epoxy.

[1] The type specimens are currently preserved in the paleoentomology collections housed in the American Museum of Natural History, located in Manhattan, New York City, US.

The two specimens were examined by Alexandr P. Rasnitsyn, who identified them as belonging to the chrysidoid family Plumariidae.

Brothers 2011 type description of the family, genus, and species was published online and in print in the journal ZooKeys.

[1] Based on the phylogenetic analysis that were run by Brothers Plumalexius is a basal genus in the evolution of the family Plumariidae, however the genus does not display the apomorphies that are key for Plumariidae.