Class [Mammalia] Linnaeus, 1758 - mammals
   Order Primates Linnaeus, 1758 - primates
     Family Cercopithecidae Gray, 1821 - Old World monkeys
       Subfamily Colobinae Jerdon, 1867
         Genus Pygathrix Geoffroy Saint-Hilaire, 1812 - douc langurs
           1 Pygathrix avunculus (Dollman, 1912) - Tonkin snub-nosed monkey see Rhinopithecus avunculus (Dollman, 1912)
           2 Pygathrix brelichi (Thomas, 1903) - Brelich's snub-nosed monkey see Rhinopithecus brelichi (Thomas, 1903)
           3 Pygathrix nemaeus (C. Linnaeus, 1771) - douc langur
           4 Pygathrix roxellana (Milne-Edwards, 1870) - Chinese snub-nosed monkey see Rhinopithecus roxellana (Milne-Edwards, 1870)