Taxonomy History

Possible changes to ICTV Taxa

Definitions for the  possible actions describing changes to the ICTV taxonomy from one release to another are indicated below. Note that each action (other than ‘Assigned as Type Species’ which will no longer be used since type species will no longer be assigned after MSL #35, 2019) can, for the most part, happen at any taxon rank from Species to the top level of Realm. In addition, similar to the description of ‘Split’ below, some changes could be accomplished with a smaller set of actions. But the actions below are used to be sure that the complete history of changes to ICTV taxa are described and maintained from one release to another.

  • Abolished: The taxon is abolished (deleted) from the MSL. All constituent taxa need to be moved, otherwise they will also be deleted.
  • Merged: Two separate taxa will be merged into a single taxon. The single taxon may be one of the initial two, or it could be a newly created taxon. All constituent, lower rank members will be automatically moved into the merged taxon.
  • Moved: A lower rank taxon and its constituent members is moved from one higher rank taxon to another. (The move usually, but not necessarily, is to a taxon (existing or new) at the same rank as the original parent.)
  • New: Creation of a new taxon. New ranks higher than Species must contain new (or moved) lower-rank members.
  • Promoted: A lower rank taxon is moved to a higher rank (usually also requiring a rename). This does NOT necessarily imply that the constituent members of the promoted taxon are subject to any change.
  • Demoted: (This one is new for 2020.) A higher rank taxon is moved to a lower rank (potentially requiring a rename). This does NOT necessarily imply that the constituent members of the promoted taxon are subject to any change.
  • Renamed: A taxon is renamed. The new name must adhere to the naming rules of the ICTV Code of Virus Classification and Nomenclature.
  • Split: A taxon, along with its constituent members, are split into two or more taxa. The original taxon that was split may, or may not, be retained, and the resulting set of taxa into which the original was split, may consist of existing or new taxa. The change must be accompanied with an indication of where each of the constituent member taxa are to be moved. Theoretically, this action could be accomplished with a combination of changes involving Moved, Abolished, and New, but was created to maintain the history of all changes to the original taxon and its members.
  • Assigned as Type Species: Flag the species as the type species for its parent genus. Only one type species may exist for a single genus.