Background Oidaematophorus pseudotrachyphloeus Gielis, 2011 (Lepidoptera, Pterophoridae) is a little-known Neotropical plume moth previously recorded in Ecuador, Peru and Argentina. Its host plants and DNA barcodes are unknown. New information Oidaematophorus pseudotrachyphloeus is recorded for the first time from Chile, based on six specimens from the Azapa Valley (Arica Province) and two from Guayacan (Coquimbo Province). Those from the Azapa Valley were reared from folivorous larvae collected on Ambrosia cumanensis Kunth (Asteraceae), representing the first host plant record for this plume moth. The first DNA barcode sequences of O. pseudotrachyphloeus are provided and used to explore relationships with congenerics.