Pegivirus is the approved name for a genus of single positive stranded RNA viruses in the family Flaviviridae. The name is a derived one: 'Pe' stands for 'persistent' and 'g' is a reference to Hepatitis G, a former name of the C species. There are eleven named species within the genus Pegivirus. Isolates belonging to the species Pegivirus C are monophyletic and show < 50% nucleotide (55% amino acid) sequence divergence between aligned sequences from the polyprotein from each other. However all differ by >50% nucleotide (>55% amino acid) divergence from other members of this genus. Pegiviruses assigned to this species (Pegivirus A) originate from primate host species (humans, chimpanzees and several New World monkey species). The sequence U22303 has been assigned as the type member of the species as this was the first pegivirus to be described for this species. Terminology to describe viruses with different hosts has not been approved by the International Committee on Taxonomy of Viruses (ICTV); however, Pegivirus A viruses have been called HPgV for human pegivirus, SPgV for new world simian pegiviruses, and SPgVcpz for chimpanzee simian virus. This remains an area requiring further clarification. A second species within the pegiviruses is termed Pegivirus B. Only one virus was included in the naming proposal, which was a complete genome of a virus found in the bat species Pteropus giganteus. This sequence differs by >50% nucleotide (>55% amino acid) divergence from all proposed members of the primate-derived Pegivirus C species that originate from primate host species (humans, chimpanzees and several New World monkey species). The sequence GU566734 has been assigned as the type member of the species as this was the first pegivirus to be described for this species. The use of deep sequencing technologies has identified additional viruses that differ from Pegivirus B species by >50% nucleotide (>55% amino acid) and Pegivirus C in rodents, horses, and in different bat species, and old world monkeys and the number of Pegivirus species has been expanded to eleven. The species known in 2016 have been classified into 11 species—Pegivirus A–K.