This research sheds light on the phylogenetic position of the recently described Caribbean species Duartettix montanus. Morphologically most similar to the Melanoplinae, especially the North American genus Melanoplus, it was assigned to that subfamily. The Orthoptera Species File, curiously, assigns Duartettix to the South American tribe Dichroplini. The present molecular phylogenetic analysis of portions of four mitochondrial genes, however, strongly rejects that allocation and instead supports an association with the northern melanoplines. Within the context of an “Out-of-South America” hypothesis proposed earlier for the subfamily's origin, it is speculated that the antecedents of Duartettix arose from ancestors on their northward movement, traversing a series of island arcs that intermittently connected the two Americas during the late Cretaceous. Of possible taxonomic interest, phylogenetic information is also provided for a number of South American melanoplines, notably members of the tribe Jivarini, which have not been previously analyzed using molecular methods.