Hesperomys was introduced by George Robert Waterhouse in 1839 for the American rodents with cusps arranged in two series.

He considered it possible that species of Hesperomys would be found in the Old World, but did not doubt that the Americas were their chief abode.

[3] In following years, authors like Johann Andreas Wagner and Spencer Fullerton Baird expanded the genus to include additional American species, such as those placed now in Scapteromys, Oxymycterus, Abrothrix, and Peromyscus.

He did not use Calomys (introduced by Waterhouse in 1837 for Mus bimaculatus), because he thought it to be preoccupied by an earlier name Callomys d'Orbigny and Geoffroy, 1830.

[5] In 1962, Philip Hershkovitz noted that the International Code of Zoological Nomenclature mandates that a name cannot be considered preoccupied even when it differs by only one letter from another, so Callomys cannot invalidate Calomys.