Nychogomphus was established as subgenus of
Onychogomphus by Carle (1986) with
N. geometricus as the type based on the shape of the male cerci and the secondary genitalia. Chao (1990), in his revision of Chinese gomphids elevated this taxon to genus level and transferred
Onychogomphus duaricus and
O. striatus to
Nychogomphus. ==Description and habitat==