Panthera is a genus of the family Felidae (cats), which contains four well-known living species: the tiger, the lion, the jaguar, and the leopard. The genus comprises about half of the Pantherinae subfamily, the big cats. The word panther, while technically referring to all members of the genus, is commonly used to specifically designate the black panther, a melanistic jaguar or leopard, and the Florida panther, a subspecies of cougar (Puma concolor coryi).
Only the four Panthera cat species have the anatomical structure that enables them to roar. The primary reason for this was formerly assumed to be the incomplete ossification of the hyoid bone. However, new studies show that the ability to roar is due to other morphological features, especially of the larynx. The snow leopard, Uncia uncia, which is sometimes included within Panthera, does not roar. Although it has an incomplete ossification of the hyoid bone, it lacks the special morphology of the larynx.
However, due to more recent genetic studies, the snow leopard is now becoming more generally considered as Panthera uncia and is presently classified as such by IUCN.
Read more about Panthera: Name, Evolution, Species, Subspecies, and Populations