Cephalic shield morphology as species diagnostic trait and individual natural mark in three-banded armadillos (Tolypeutes; Cingulata: Chlamyphoridae)

Previous studies have suggested species- and individual-specific morphologies of cephalic shields of three-banded armadillos (Tolypeutes spp.). Central cephalic scutes would form discrete lines; the first two posterior lines being composed of one scute (1-1) in Tolypeutes matacus and one followed by two scutes (1-2) in Tolypeutes tricinctus. However, conclusions were limited to a few specimens and the T. tricinctus pattern was later observed in T. matacus. Here, we assessed the potential use of the morphology of the cephalic shield as a species diagnostic trait and individual natural mark in three-banded armadillos by quantifying their patterns in museum (n = 71) and field (n = 82) specimens. In total, 93% of T. matacus and 88% of T. tricinctus specimens presented the respective species' character states. All specimens could be individualized based on a visual comparison of their cephalic shields. Our findings show that the morphology of cephalic shields is a species diagnostic trait and an individual natural mark in three-banded armadillos. Therefore, we add an accessible character for species diagnosis in Tolypeutes and provide an alternative to artificial marks that presents virtually no associated cost and damage to animal welfare and can be reliably applied in ecological and participatory science projects.