After Prothero & Schoch, 1989, Hulbert, 1989, Winans, 1989, Nowak, 1991, MacFadden, 1997, Alberdi, Ortiz-Jaureguizar & Prado, 1998 and Eisenmann & Baylac, 2000

<==o Equus Linnaeus, 1758 sensu lato [Synonyms] (horses; hevoset)
   |--o †(Amerhippus) Hoffstetter, 1950 (south american horses; eteläamerikanhevoset)
   |  |-- †E. (A.) insulatus Ameghino, C., in Ameghino, F., 1904
   |  |-- †E. (A.) andium Wagner-Branco, 1883
   |  |-- †E. (A.) lasalli Daniel, 1948
   |  |-- †E. (A.) santae-elenae Spillman, 1938
   |  |-- †E. (A.) martini spillman, 1938
   |  |-- †E. (A.) curvidens Owen, 1844
   |  `-- †E. (A.) neogeus Lund, 1840 emend. MacFadden & Azzaroli, 1987
   |--o (Equus) Linnaeus, 1758 (true horses; aitohevoset) [Note: some taxonomist separate horse subspecies to independent species]
   |  |-- E. (E.) caballus Linnaeus, 1758 (domestic horse; kesyhevonen)
   |  |-- E. (E.) przewalskii (Przewalski's horse, mongolian wild horse; przewalskinhevonen)
   |  `--o †E. ferus Boddaert, 1785 (wild horse, tarpan; hevonen, tarpaani, villihevonen)
   |     |-- †E. (E.) f. gmelini (plain tarpan; arotarpaani)
   |     |-- †E. (E.) f. silvatica (forest tarpan; metsätarpaani)
   |     `-- †E. (E.) f. remagensis
   `--+--o (Hemionus) (asian donkeys; aasianvilliaasit)
      |  |?-o †E. francisci -species-group [are members of subgenus Equus? (Eisenmann & Baylac, 2000)]
      |  |  |-- †E. (H.) francisci Hay, 1915
      |  |  |-- †E. (H.) altidens Quinn, 1957
      |  |  |-- †E. (H.) arellanoi Mooser, 1958
      |  |  |-- †E. (H.) quinni Slaughter et al., 1962
      |  |  `-- †E. (H.) zoytalis Mooser, 1958
      |  |--o E. (H.) hemionus (aasianvilliaasi)
      |  |  |-- E. (H.) h. hemionus (kulaani)
      |  |  |-- E. (H.) h. kulan (kulaani)
      |  |  `-- †E. (H.) h. hemippus (syyrianvilliaasi)
      |  |--o E. (H.) onager (onageri)
      |  |  |-- E. (H.) o. onager (onageri)
      |  |  `-- E. (H.) o. khur (intianvilliaasi)
      |  `--  E. (H.) kiang (kiangi)
      |--o (Asinus) Frisch, 1775) (african donkeys; afrikanvilliaasit)
      |  |-- †E. (A.) calobatus Troxell, 1915
      |  `--o E. (A.) africanus Heauglin & Fitzinger, 1866 (ass, donkey; aasi, kesyaasi)
      |     |-- E. (A.) a. asinus Linnaeus, 1758 (domestic ass, donkey; kesyaasi)
      |     |-- E. (A.) a. africanus Heauglin & Fitzinger, 1866 (afrikanvilliaasi, nuubianvilliaasi)
      |     |-- E. (A.) a. atlanticus ()?
      |     `-- E. (A.) a. somalicus (somalinvilliaasi)
      `--+--o (Dolichohippus) Heller, 1912
         |  |-- †E. (D.) numidicus Pomel, 1897
         |  |-- †E. (D.) oldowayensis Hopwood, 1937
         |  |-- †E. (D.) koobiforensis
         |  `-- E. (D.) grevyi Oustalet, 1882 (Grevy's zebra; grevynseepra)
         |--o (Hippotigris) Smith, H., 1841 (mountain zebras; vuoriseeprat)
         |  `--o E. (H.) zebra Linnaeus, 1758 (vuoriseepra)
         |     |-- E. (H.) z. zebra (kapmaanvuoriseepra)
         |     `-- E. (H.) z. hartmannae (hartmanninvuoriseepra)
         `--o (Quagga) (plain zebras, quaggas; aroseeeprat)
            |?- †E. ?(Q.) capensis Broom, 1909 [is a member of subgenus Equus? (Eisenmann & Baylac, 2000)]
            |?- †E. ?(Q.) mauritanicus [is a member of subgenus Equus? (Eisenmann & Baylac, 2000)]
            |-- †E. (Q.) quagga Gmelin, 1788 (quagga; kvagga) [ssp.=>E. burchellii??] [extinct since 1880]
            `--o E. (Q.) burchellii (Gray, 1824) (plain zebra; aroseepra)
               |-- E. (Q.) b. antiquorum (damaranseepra)
               |-- E. (Q.) b. boehmi (böhminseepra)
               |-- E. (Q.) b. chapmanni (chapmanninseepra)
               |-- E. (Q.) b. foai (foanseepra)
               |-- E. (Q.) b. granti (grantinseepra)
               |-- E. (Q.) b. wahlbergi (wahlberginseepra)
               `-- E. (Q.) b. burchellii (burchellinseepra)


Equus incertae sedis:
[I have no idea where these animals belong within Equus!?]

    †E. fromaniusE. idahoensisE. alaskae -species-group
        †E. pacificus Leidy
        †E. alaskae (Hay, 1913) [E. niobrarensis alaskae Hay, 1913]
        †E. conversidens Owen, 1869
            †E. c. leoni Stock, 1950
        †E. lambei Hay, 1917
    †E. scotti -species-group [are members of subgenus Equus? (Eisenmann & Baylac, 2000)]
        †E. scotti Gidley, 1900
        †E .sp. cf. E. scotti Gidley, 1900
        †E. niobrarensis Hay, 1913
        †E. hatcheri Hay, 1915
    †E. complicatusE. cumminsiiE. enormisE. fraternusE. giganteusE. leidyiE. occidentalis Leidy [is a member of subgenus Equus? (Eisenmann & Baylac, 2000)]
    †E. pacificusE. pectinatusE. verae
    †(Hesperohippus) [=? E. laurenticus -species-group]
        †E. (H.) laurenticus Hay, 1913
        †E. (H.) mexicanus Hibbard, 1955
        †E. (H.) midlandensis Quinn, 1957
        “European stenonoid horses” [Alberdi, Ortiz-Jaureguizar & Prado, 1998] [are members of sub-genus Dolichohippus?]
            †E. (H.) major Depéret, in Delafond & Depéret, 1893, ex Boule
            †E. (H.) stenonis Cocchi, 1867
            †E. (H.) livenzovensis Bajgusheva, 1978
            †E. (H.) senezensis Prat, 1964
            †E. (H.) altidens von Reichenau, 1915
            †E. (H.) sussenbornensis Wüts, 1901
    “East Asian stenonoid horses” [Eisenmann & Baylac, 2000]
        †E. nalaikhaensis [is a member of subgenus Dolichohippus? (Eisenmann & Baylac, 2000)]
        †E. sanmeniensisE. sp. cf. E. sanmeniensisE. qingyangensisE. yunnanensisE. exelsusE. euilus [Ethiopia]
    †(Plesippus) Matthews, 1924 sensu stricto? [Allohippus Kretzoi, 1938]
        †E. (D.) simplicidens Cope, 1892
        †E. (D.) pons Quinn, 1958
        †E. (D.) shoshonensis Gidley, 1930 [ssp. => E. simplicidens??]

Reference(s):