The adult stage of Rhectosemia azapaensis new species (Lepidoptera: Pyraloidea: Crambidae: Spilomelinae: Lineodini) from the transverse valleys of the Atacama Desert of northern Chile is described and illustrated. The morphology of the male and female genitalia resembles that of R. antofagastalis , the only representative of the genus previously known from the Atacama Desert. However, the two species can be accurately separated based on wing pattern and the morphology of the juxta and fibula. Similarity between DNA barcode sequences of the two species was 93.86%. Larvae of R. azapaensis feed within fruits of the native Solanum peruvianum L. (Solanaceae) and exit the fruit for pupation. This discovery represents the first host plant record for Rhectosemia Lederer and agrees with the more widespread host plant family used by species of Lineodini.