Class Mammalia Linnaeus, 1758 - mammals
   Subclass Theria Parker & Haswell, 1897
     Order Primates Linnaeus, 1758 - primates
       Suborder Haplorrhini Pocock, 1918 see Suborder Haplorhini Pocock, 1918
         Infraorder Simiiformes Haeckel, 1866
           Parvorder Catarrhini Geoffroy Saint-Hilaire, 1812
             Superfamily Cercopithecoidea Gray, 1821
               Family Cercopithecidae Gray, 1821 - Old World monkeys
                 Subfamily Colobinae Jerdon, 1867
                   Genus Pygathrix Geoffroy Saint-Hilaire, 1812 - douc langurs
                     1 Pygathrix cinerea Nadler, 1997
                     2 Pygathrix nemaeus (C. Linnaeus, 1771) - douc langur
                     3 Pygathrix nigripes (Milne-Edwards, 1871) - douc langur