The extinct clupeomorph genus Armigatus has been included in a number of phylogenetic analyses, with disagreement about its placement and relationships among the fishes of the extinct clupeomorph order Ellimmichthyiformes. There are currently four species known, all from the Late Cretaceous Tethys Sea. Here we describe a fifth species of Armigatus from Campanian deposits of Dalmatia and present a phylogenetic analysis of the genus. The new species is found to be sister group to A. oligodentatus from Morocco, and the two together form the sister group to the species from Lebanon, A. namourensis plus A. brevissimus (A. alticorpus was excluded because of lack of data). The genus Armigatus is found to be monophyletic, as are the included members of its sister group, Diplomystus, and the analysis supports the grouping of these two genera in the family Armigatidae. The relationships among the species of Armigatus indicate that these fishes arose in the eastern part of the central Tethys, then from there reached more northern (Dalmatian) and western (Morocco) areas.