The data published below attempts to track the development of ICTV taxonomy from the publication of the First Report in 1971.
The early published reports consisted of brief summaries of the genera officially recognized by ICTV (and a small number of families) with lists of viruses that were considered members and possible members of these genera. One of the member viruses was identified as the type member. Plant viruses were presented in ‘groups’ until more data were available to determine whether these groups corresponded to genera or families. All such groups had disappeared by 1993. Virus species were systematically introduced for the Seventh Report (1999). In many cases, these species lists corresponded to the viruses listed earlier as genus members but in some genera closely related viruses were classified into a single species. This explains the apparent drop in total numbers of species recognized between 1998 and 1999. Possible or probable members of genera and families were then listed as ‘tentative species’.
For the purpose of these pages, the viruses listed as genus ‘members’ from 1971-1995 are treated as species. The ‘groups’ are usually treated as genera. No attempt has been made to list ‘possible members’ or ‘tentative species’. Where changes to taxonomy occurred, links are provided to proposal documents or other records (e.g. minutes recording the results of ICTV ballots) where available. Before about 1996, there were not usually specific proposals and ballots of ICTV members to establish new member viruses (or species) and the lists were revised (sometimes extensively) by the relevant Study Groups when each ICTV Report was published. Many changes can therefore only be traced to the publication of a particular Report.