the root (no rank)
Eukaryota (domain)
Metazoa (kingdom)
Chordata (phylum)
Craniata (subphylum)
Vertebrata (no rank)
Gnathostomata (superclass)
Sarcopterygii (class)
Tetrapoda (no rank)
Amniota (no rank)
Sauropsida (no rank)
Sauria (no rank)
Lepidosauria (superorder)
Squamata (order)
Serpentes (suborder)
Colubroidea (superfamily)
Viperidae (family)
Crotalinae (subfamily)
Agkistrodon (genus)
Agkistrodon halys (species)
halys viper (primary common name)
[hide inferior taxa]
Agkistrodon halys brevicaudus (subspecies)
Agkistrodon halys pallas (subspecies)