The purpose of this application, under Article 75.5 of the Code, is to designate a neotype for Belostoma ellipticum Latreille, 1833. This species has been accepted by heteropterists since 1962, but it is actually a nomen dubium, since Latreille designated neither types nor a type locality and provided little descriptive information. Subsequent to Latreille, in the absence of a useful diagnosis, authors referred specimens of several other taxonomically valid taxa to B. ellipticum. Belostoma ellipticum sensu Lauck, 1962, however, is readily defined by the presence of a pair of conspicuous notches along the lateral margins of the ventral diverticulum of the phallus in ventral view, and it is this concept of the species that has gained general acceptance. Fixation of a neotype displaying this feature, which cannot be confirmed in any potentially syntypic Latreille specimen of the subspinosum group in Carreno's collection at the Museo Nacional de Ciencias Naturales, Madrid, will facilitate retention of B. ellipticum as a valid species name.