the root (no rank)
Viruses (domain)
retroid viruses (subkingdom)
Retroviridae (family)
Spumaretrovirinae (subfamily)
Spumavirus (genus)
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bovine foamy virus (species)
bovine syncytial virus (species)
equine foamy virus (species)
feline foamy virus (species)
feline spumavirus (species)
human foamy virus (species)
human spumaretrovirus (species)
macaque simian foamy virus (species)
simian foamy virus (species)