Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           ?"viruses"
             Family Bicaudaviridae [monotypic]
               Genus Bicaudavirusᵀ [monotypic]
                 1 Acidianus two-tailed virusᵀ