Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
   Subclass Neornithes Gadow, 1893 see Clade Neornithes Gadow, 1893
     Infraclass Neoaves Sibley et al., 1988 see Subcohort Neoaves Sibley et al., 1988
       Parvclass Passerae see Superorder Passerimorphae Sibley et al., 1988
         Superorder Apodimorphae see Order Apodiformes Peters, 1940
           Order Trochiliformes Wagler - hummingbirds see Suborder Apodi Peters, 1940
             Family Trochilidae Vigors, 1825 - hummingbirds
               Subfamily Trochilinae Jardine, 1833 - typical hummingbirds
                 Genus Popelairia Reichenbach, 1854 see Genus Discosura Bonaparte, 1849
                   1 Popelairia popelairii (Du Bus de Gisignies, 1846) - wire-crested thorntail see Discosura popelairii (Du Bus, 1846)
                   2 Popelairia langsdorffi (Temminck, 1821) - black-bellied thorntail see Discosura langsdorffi (Temminck, 1821)
                   3 Popelairia letitiae (Bourcier & Mulsant, 1852) - coppery thorntail see Discosura letitiae (Bourcier & Mulsant, 1852)
                   4 Popelairia conversii (Bourcier & Mulsant, 1846) - green thorntail see Discosura conversii (Bourcier & Mulsant, 1846)