This bird was first described and illustrated in 1801 by the French naturalist François Le Vaillant for his "Histoire Naturelle Des Perroquets" under the name "le grand Ara militaire", using a skin deposited at the Muséum national d'histoire naturelle in Paris. Le Vaillant states that it is not certain if the bird is truly a distinct species of parrot, or, as he thinks more likely, it is specific varietal race of the military macaw, but nonetheless, he must mention that its existence merits notice. The bird was subsequently named "Psittacus ambiguus" by the Thuringian Johann Matthäus Bechstein in the first tome of the fourth volume, published in 1811, of the series "Johann Latham's Allgemeine Uebersicht der Vögel", the greatly expanded German translation of the Englishman John Latham's "A General Synopsis of Birds". Bechstein mentions le Vaillant's reluctance to consider it as an independent species, but explains that having examined a living bird, he considers it a valid species, mentioning the size difference and enumerating numerous other characteristics he deems distinctive.