Some include Placozoa , a phylum that consists of only one species , Trichoplax adhaerens , in the division , but they are also sometimes placed in the subkingdom Agnotozoa . Some authors include Placozoa , a phylum that consists of only one species , Trichoplax adhaerens , in the division , but they are also sometimes placed in the subkingdom Agnotozoa .