| Nialaphodius nigrita (Fabricius, 1801) |
| Nobius Mulsant & Rey, 1870 |
| Nobius consentaneus (LeConte, 1850) |
| Odontopsammodius Gordon & Pittino, 1992 |
| Odontopsammodius formosus Cartwright, 1955 |
| Odontopsammodius integer Bates, 1887 |
| Oncerini LeConte, 1861 |
| Oncerus LeConte, 1856 |
| Oncerus convergens (Horn, 1894) |
| Oniticellina Kolbe, 1905 |
| Oniticellini Kolbe, 1905 |
| Oniticellus Audinet-Serville, 1825 |
| Oniticellus monstrosus Bates, 1887 |
| Oniticellus rhinocerulus Bates, 1887 |
| Ontherus Erichson, 1847 |
| Ontherus (Caelontherus) Génier, 1996 |
| Ontherus (Caelontherus) mexicanus Harold, 1868 |
| Ontherus (Ontherus) Erichson, 1847 |
| Ontherus (Ontherus) azteca Harold, 1869 |
| Onthophagini Burmeister, 1846 |