The genus Downeshelea was described by Wirth and Grogan based on the diagnostic characters of the Monohelea multilineata species group. The first descriptions of species were based on body coloration, which resulted in confusion and misunderstanding of their identification. The aim of this study was to provide an updated diagnosis and description of Downeshelea, describe 18 new species, and redescribe 10 previously poorly described species. New records of species, a key for identification of all New World species, and a table with important morphometric data to distinguish both males and females of the various species are provided along with distribution maps of the 46 known New World species.