What does "turnus" mean?

Turnus: A common, large, handsome, American swallowtail butterfly, now regarded as one of the forms of Papilio, or Jasoniades, glaucus. The wings are yellow, margined and barred with black, and with an orange- red spot near the posterior angle of the hind wings. Called also tiger swallowtail. See Illust. under Swallowtail.