Notodiaptomus is a genus of copepods in the family Diaptomidae. It is the most widely distributed, most abundant and most species-rich genus of freshwater calanoid copepods in the Neotropics. The genus was erected in 1936 by Friedrich Kiefer for eleven species formerly placed in a wider Diaptomus. was chosen to be the type species by Raúl Adolfo Ringuelet in 1958.