This study investigated the systematics of the Nearctic shield-back katydids (“Tettigoniinae”), a paraphyletic group thought to include genera from a distinctive Gondwanan tribe, the Nedubini, among an otherwise Holarctic fauna. From exemplars of five genera of Nedubini and the majority of other genera of Nearctic “Tettigoniinae,” five gene regions were sequenced, aligned with publicly available sequence data that represent diverse subfamilies of Tettigoniidae, and subjected to phylogenetic analysis under Bayesian and likelihood criteria. Our results render the worldwide Nedubini polyphyletic, strongly support the Nearctic Nedubini as a basal clade that is sister to the remaining Tettigoniidae, and group the remaining Nearctic shield-back katydid genera into a Holarctic clade. Having shared a common ancestor with the remaining katydids 175 ± 24 million years ago, the Nearctic Nedubini joins a considerable assemblage of relict groups that are found in California and the Pacific Northwest of North America. The symmetrical development and ambidextrous overlap of the tegmina of male Nearctic nedubines is re-evaluated as a plesiomorphic character.