The genus Plenoculus Fox was erected in Psyche, Vol. VI, 1893, p. 554, with one species P. davisi. Since that time, however, four additional species have been described, three by Fox and one by myself. I have now the pleasure of presenting descriptions of four new species and giving a table for distinguishing all of the species, The genus is unknown outside of boreal North America.
Ashmead, William H., "Four New Species Belonging to the Genus Plenoculus Fox" (1899). An. Paper 70.