In a recent study by Ware et al. (2017) there is strong evidence from molecular phylogenetics that the genus Onychogomphus is not monophyletic. Indeed, the pale Asian species (e.g. O. lefebvrii, O. assimilis, O. flexuosus, O. macrodon) and the mediterranean O. costae deviate quite significantly from typical Onychogomphus and likely belong really in other genera. Ware et al. (2017) suggest that only the taxa forcipatus and uncatus truly belong to Onychogomphus and the other species require significant revision. I agree with this notion; at any rate, the unresolved relationships of onychogomphid taxa does not affect the valid names of the two German species, because one is the type species of Onychogomphus (forcipatus) and the other (uncatus) is its sister species and therefore undoubtedly con-generic.

Additional English name: Green-eyed Hooktail.