International Commission on Zoological Nomenclature
 INTERNATIONAL CODE OF ZOOLOGICAL NOMENCLATURE online

Article 2. Admissibility of certain names in zoological nomenclature.

2.1. Names of taxa later but not at first classified as animals. For the conditions under which such names enter zoological nomenclature, see Article 10.5.

2.2. Names of taxa at some time but not later classified as animals. Any available name of a taxon that has at any time been classified as animal continues to compete in homonymy in zoological nomenclature even though the taxon is later not classified as animal.