The purpose of this application, under Article 23.9.5 of the ICZN Code, is to conserve the specific name Gyrinus glaucus Aubé, 1838 (currently Macrogyrus (Andogyrus) glaucus; Gyrinidae, Gyrininae, Dineutini). The name is threatened by the senior primary homonym Gyrinus glaucus Klug, 1834 (currently Orectogyrus (Orectogyrus) glaucus; Gyrinidae, Gyrininae, Dineutini). Although the two names were transferred out of the genus Gyrinus Geoffroy, 1762 and have never been treated as congeneric, they are nevertheless primary homonyms. Both names have been treated as valid since they were proposed. Klug's name was classified by Aubé with the generic name Orectochilus and since its transfer to Orectogyrus by Régimbart in 1884, it has always been given with this generic name. Aubé's name was combined with the generic name Macrogyrus by Régimbart, with the generic name Andogyrus since Ochs in 1924, and with Macrogyrus (Andogyrus) since Gustafson and Miller in 2017. It is proposed that Gyrinus glaucus Aubé, 1838 be conserved by ruling that it is not invalid by reason of being a junior homonym of Gyrinus glaucus Klug, 1834.