Equus caballus

Familia: Equidae
Subfamilia: Equinae
Tribus: Equini
Genus: Equus
Species: Equus caballus

Equus caballus Linnaeus, 1758

• Type locality: "Habitat in Europa" (= Sweden?); based on domestic horses.
• Original combination: Equus Caballus Linnaeus, 1758

• Equus ferus caballus Linnaeus, 1758 [if treated as subspecies of ferus, which name should have priority over the domestic form at species level per ICZN Opinion 2027; conversely, MSW 3 treated ferus as a subspecies of caballus, but see below]. Note, as at May 2023, the term Equus ferus caballus is still used in the scientific literature for the domestic horse (example: 3,120 hits on Google Scholar, date range 2010-2023), but less frequently than Equus caballus over the same period ("about 18,000 results").
• Equus caballus caballus Linnaeus, 1758: Wilson & Reeder, Mammal Species of the World (3rd edition), 1995 - online version at https://www.departments.bucknell.edu/biology/resources/msw3/browse.asp?id=14100016 [incorrect]. This treatment is equivalent to the above, i.e. domestic horse treated as a subspecies of a larger taxon covering both domestic and wild horses, except in MSW 3's view the correct specific name for the larger taxon was caballus, not ferus. In this view, the larger taxon is caballus and its included subspecies are then caballus (nominate subspecies), ferus (as E. c. ferus) and przewalskii (as E. c. przewalskii). However, the selection of caballus for the name of the larger, more inclusive taxon was later recognised to have been an error made at the time by the author of that section based on a mis-interpretation of ICZN Opinion 2027, but one that could not subsequently be corrected in the print version, for full details refer Groves & Grubb, 2011, p. 8.

Note that more recent authorities tend to treat both caballus and ferus as separate species, while generally (but not exclusively) retaining przewalskii at subspecies level, i.e. of ferus as per the Mammal Diversity Database; for an alternative view regarding the ranking of the latter taxon, refer Groves & Grubb, 2011.

• Linnaeus, C. 1758. Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Editio Decima, Reformata. Tomus I. Holmiæ (Stockholm): impensis direct. Laurentii Salvii. 824 pp. DOI: 10.5962/bhl.title.542 BHL p. 73 BHL Reference page. 

• Groves, C.; Grubb, P. (2011). Ungulate Taxonomy. Baltimore, USA: Johns Hopkins University Press. p. 179. ISBN 978-1-4214-0093-8.
• ICZN 2003. OPINION 2027 (Case 3010). Usage of 17 specific names based on wild species which are pre-dated by or contemporary with those based on domestic animals (Lepidoptera, Osteichthyes, Mammalia): conserved. Bulletin of Zoological Nomenclature 60(1): 81–85. BHL Reference page. 

• Equus caballus in Mammal Species of the World.
  Wilson, Don E. & Reeder, DeeAnn M. (Editors) 2005. Mammal Species of the World – A Taxonomic and Geographic Reference. Third edition. ISBN 0-8018-8221-4. [as caballus caballus within an enlarged caballus [error for ferus], the latter also including ferus and przewalskii as other subspecies - not followed here]
• Equus caballus – Taxon details on Integrated Taxonomic Information System (ITIS).
• Equus caballus in ASM Mammal Diversity Database.

For more multimedia, look at Equus caballus on Wikimedia Commons.