Imperium naturæ C. Linnaeus, 1758 - nature
   Mundus Plinius - physical world
     naturalia - natural bodies
       Regnum Animale C. Linnaeus, 1758 - animal kingdom see Kingdom Animalia Linnaeus, 1758
         Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
           Order Picae Linnaeus, 1758 see Parvclass Picae (C. Linnaeus, 1758)
             Genus Picus Linnaeus, 1758
               01 Picus martius Linnaeus, 1758 see Dryocopus martius (C. Linnaeus, 1758)
               02 Picus principalis Linnaeus, 1758 see Campephilus principalis (C. Linnaeus, 1758)
               03 Picus pileatus Linnaeus, 1758 see Dryocopus pileatus (C. Linnaeus, 1758)
               04 Picus hirundinaceus Linnaeus, 1758
               05 Picus erythrocephalus Linnaeus, 1758 see Melanerpes erythrocephalus (C. Linnaeus, 1758)
               06 Picus carolinus Linnaeus, 1758 see Melanerpes carolinus (C. Linnaeus, 1758)
               07 Picus viridis Linnaeus, 1758 - Eurasian green woodpecker
               08 Picus benghalensis Linnaeus, 1758 see Dinopium benghalense (C. Linnaeus, 1758)
               09 Picus semirostris Linnaeus, 1758
               10 Picus major Linnaeus, 1758 see Dendrocopos major (C. Linnaeus, 1758)
               11 Picus medius Linnaeus, 1758 see Dendrocopos medius (C. Linnaeus, 1758)
               12 Picus minor Linnaeus, 1758 see Dendrocopos minor (C. Linnaeus, 1758)
               13 Picus tridactylus Linnaeus, 1758 see Picoides tridactylus (C. Linnaeus, 1758)