A new early Irvingtonian (latest Pliocene) rodent fauna is reported here from Inglis 1C, Citrus County, Florida. This sinkhole deposit near the west coast of the state contains 33 species of mammals, including 11 rodents, of which six are now extinct. A new species of Peromyscus, P. sarmocophinus, sp. nov., is described from this locality and the slightly older Inglis 1A. Inglis 1C contains the oldest records of three rodents (Peromyscus polionotus, Reithrodontomys humulis, and Atopomys texensis) and the youngest occurrences of two others (Reithrodontomys wetmorei and Ondatra idahoensis). Additionally, the paleogeographic range of two taxa, R. wetmorei and Baiomys sp., is extended east of the Mississippi River.

Deposition at Inglis 1C was nearly contemporaneous with, the better-known, early Irvingtonian Inglis 1A fauna. The two localities share Sciurus sp., Glaucomys sp., Orthogeomys propinetis, Sigmodon curtisi, P. sarmocophinus, sp. nov., R. wetmorei and O. idahoensis. A slightly younger age at Inglis 1C is implied by the presence of P. polionotus, R. humulis, and Atopomys texensis. This fauna serves as an older complement to Florida's other well studied Irvingtonian localities, Leisey Shell Pits, Hillsborough County, and Coleman 2A, Sumter County.