The genus Cruzia was proposed by Travassos, 1917 for Ascaris tentaculata Rudolphi, 1819, from Didelphys spp. In the same year, he also erected a new family Cruziidae for the reception of this genus. In 1926, another species C. mexicana Khalil, 1926, was added to this genus, from an undetermined species of lizard. Khalil did not recognise the family Cruziidae, or even the subfamily Cruziinae, proposed by Ortlepp, 1924. Baylis and Daubney, 1926, placed the genus Cruzia in the family Kathlaniidae. Canavan, 1929, recorded some specimens from Didelphys marsupialis virginiana which were named Cruzia americana by Maplestone, 1931. This was later synonymised with the type species C. tentaculata by Wolfgang, 1951. In 1931 the following species were added: C. orientalis Maplestone, from domestic pig from India; C. fulleborni Khalil and Vogelsang, from Tupinambis teguixin. The latter authors also described C. mazza from Tato novecindus and C. travassosi from Tolypeutes conurus in 1932. In the same year, Sprehn recorded C. boliviana from Tolypeutes conurus and C. testudinis was described by Hanvood from Terrapene carolina trianguis. Pearse, 1936, described C. morleyi from Bufo marinus. Ruiz, 1947, revised the genus Cruzia and described a new species C. rudolphii from Erythrolamprus aesculapii and more recently, Wolfgang, 1951, added C. cameroni to it, from Didelphys marsupialis.