| Cactaceae | |
Echinocactus horizonthalonius subsp. australis
| M.A. Baker | Diversity (Basel) 14(12, 1020): 11 | 2022 |
| Cactaceae | |
Echinocactus horizonthalonius fo. centrispinus
| (Engelm.) Schelle | Kakteen 186 | 1926 |
| Cactaceae | |
Echinocactus horizonthalonius var. centrispinus
| Engelm. | Proc. Amer. Acad. Arts 3: 276 | 1856 |
| Cactaceae | |
Echinocactus horizonthalonius fo. curvispinus
| (Salm-Dyck) Schelle | Handb. Kakteenkult. 146 | 1907 |
| Cactaceae | |
Echinocactus horizonthalonius var. curvispinus
| Salm-Dyck | Cact. Hort. Dyck. (1849) 1849: 146 | 1850 |
| Cactaceae | |
Echinocactus horizonthalonius subsp. diabolicus
| Halda, L. Vacek & Vaško | Acta Mus. Richnov., Sect. Nat. 13(1): 1 | 2006 |
| Cactaceae | |
Echinocactus horizonthalonius var. equitans
| Schmoll | Catalog. | 1947 |
| Cactaceae | |
Echinocactus horizonthalonius subsp. horizonthalonius
| | | |
| Cactaceae | |
Echinocactus horizonthalonius var. horizonthalonius
| | | |
| Cactaceae | |
Echinocactus horizonthalonius subsp. jarmilae
| Halda & Horácek | | 2000 |
| Cactaceae | |
Echinocactus horizonthalonius var. laticostatus
| Schmoll | Catalog. | 1947 |
| Cactaceae | ! |
Echinocactus horizonthalonius subsp. nicholii
| (L.D. Benson) U. Guzmán | Cactaceae Syst. Init. 16: 17 | 2003 |
| Cactaceae | ** |
Echinocactus horizonthalonius subsp. nicholii
| (L.D. Benson) U. Guzmán | Cat. Cactáceas Mex. | 2003 |
| Cactaceae | |
Echinocactus horizonthalonius var. nicholii
| L.D. Benson | Cacti Arizona (ed. 3) 23, 175, f. 6.2–6.3 | 1969 |
| Cactaceae | |
Echinocactus horizonthalonius fo. obscurispinus
| (Rud. Mey.) Schelle | Kakteen 186 | 1926 |
| Cactaceae | |
Echinocactus horizonthalonius var. obscurispinus
| Rud. Mey. | Monatsschr. Kakteenk. 21: 181 | 1911 |
| Cactaceae | |
Echinocactus horizonthalonius var. subikii
| Stanik & Drab | | 1998 |