Mycobank (2025) include Rhizopogon hawkerae, Rhizopogon parksii and Rhizopogon subareolatus in Rhizopogon villosulus, while Species Fungorum (2025) treat them as distinct.
Index Fungorum and Species Fungorum. 2018. <i>In</i> Index Fungorum-Species Fungorum (<a href="https://indexfungorum.org" target="_blank">https://indexfungorum.org</a> and <a href="https://speciesfungorum.org" target="_blank">https://speciesfungorum.org</a>) database export on 16 June 2018. Royal Botanic Gardens, Kew.
Index Fungorum and Species Fungorum. 2025. <i>In</i> Index Fungorum-Species Fungorum (<a href="https://indexfungorum.org" target="_blank">https://indexfungorum.org</a> and <a href="https://speciesfungorum.org" target="_blank">https://speciesfungorum.org</a>) database export on 29 September 2025. Royal Botanic Gardens, Kew.
Kroeger, P. and S.M. Berch. 2017. Macrofungus species of British Columbia. Prov. B.C., Victoria, B.C. Tech. Rep. 108. Available online: <<a href="https://www.for.gov.bc.ca/hfd/pubs/Docs/Tr/TR108.htm">https://www.for.gov.bc.ca/hfd/pubs/Docs/Tr/TR108.htm</a>>.