| Rheomys thomasi Dickey, 1928 |
| Rheomys thomasi subsp. chiapensis Hooper, 1947 |
| Scotinomys Thomas, 1913 |
| Scotinomys teguina (Alston, 1877) |
| Scotinomys teguina subsp. subnubilus Goldman, 1935 |
| Scotinomys teguina subsp. teguina (Alston, 1877) |
| Sigmodon Say & Ord, 1825 |
| Sigmodon alleni Bailey, 1902 |
| Sigmodon alleni subsp. alleni Bailey, 1902 |
| Sigmodon alleni subsp. planifrons E. W. Nelson & Goldman, 1933 |
| Sigmodon alleni subsp. vulcani J. A. Allen, 1906 |
| Sigmodon alticola Bailey, 1902 |
| Sigmodon alticola subsp. alticola Bailey, 1902 |
| Sigmodon alticola subsp. amoles Bailey, 1902 |
| Sigmodon arizonae Mearns, 1890 |
| Sigmodon arizonae subsp. cienegae Howell, 1919 |
| Sigmodon arizonae subsp. major Bailey, 1902 |
| Sigmodon baileyi J. A. Allen, 1903 |
| Sigmodon berlandieri Baird, 1855 |
| Sigmodon colimae J. A. Allen, 1897 |