[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Platyelmia
         Branch Ciliata
           Class Planariæ
             Order Rhabdocœla Ehrenberg, 1831 see Infraclass Rhabdocoela Ehrenberg, 1831
               Genus Microstomum Schmidt, 1848