A synopsis of the genus Ethmia Hübner in Costa Rica: biology, distribution, and description of 22 new species (Lepidoptera, Gelechioidea, Depressariidae, Ethmiinae), with emphasis on the 42 species known from Área de Conservación Guanacaste

We discuss 45 Costa Rican species of Ethmia Hubner, 1819, including 23 previously described: Ethmia delliella (Fernald), Ethmia bittenella (Busck), Ethmia festiva Busck, Ethmia scythropa Walsingham, Ethmia perpulchra Walsingham, Ethmia terpnota Walsingham, Ethmia elutella Busck, Ethmia janzeni Powell, Ethmia ungulatella Busck, Ethmia exornata (Zeller), Ethmia phylacis Walsingham, Ethmia mnesicosma Meyrick, Ethmia chemsaki Powell, Ethmia baliostola Walsingham, Ethmia duckworthi Powell, Ethmia sandra Powell, Ethmia nigritaenia Powell, Ethmia catapeltica Meyrick, Ethmia lichyi Powell, Ethmia transversella Busck, Ethmia similatella Busck, Ethmia hammella Busck, Ethmia linda Busck, and 22 new species: Ethmia blaineorum, Ethmia millerorum, Ethmia dianemillerae, Ethmia adrianforsythi, Ethmia stephenrumseyi, Ethmia berndkerni, Ethmia dimauraorum, Ethmia billalleni, Ethmia ehakernae, Ethmia helenmillerae, Ethmia johnpringlei, Ethmia laphamorum, Ethmia petersterlingi, Ethmia lesliesaulae, Ethmia turnerorum, Ethmia normgershenzi, Ethmia nicholsonorum, Ethmia hendersonorum, Ethmia randyjonesi, Ethmia randycurtisi, Ethmia miriamschulmanae and Ethmia tilneyorum. We illustrate all species and their male and female genitalia, along with distribution maps of Costa Rican localities. Immature stages are illustrated for 11 species, and food plants are listed when known. Gesneriaceae is added as a new food plant family record for Ethmia. CO1 nucleotide sequences (“DNA barcodes”) were obtained for 41 of the species.