| Caatinga vesper mouse | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Cricetidae |
| Subfamily: | Sigmodontinae |
| Genus: | Calomys |
| Species: | C. expulsus |
| Binomial name | |
| Calomys expulsus (Lund, 1841) | |
The caatinga vesper mouse (Calomys expulsus) (also known as the caatinga laucha [2] or rejected vesper mouse [1] ) is a rodent species in the family Cricetidae from South America. [2] It is endemic to eastern Brazil, where it is found in open savanna (cerrado) and thorny scrub (caatinga) habitats. [1] Its karyotype has 2n = 66 and FN = 68. It was formerly synonymized with C. callosus , but the latter has 2n = 50 and FN = 66. [2] Karyologic analysis of C. expulsus has shown that the X chromosome is large and submetacentric while the Y chromosome is either acrocentric or submetacentric. [3] Predators include the barn owl . [4] Sexual dimorphism in shape and size occurs; the former is present mainly before the age of 20 days. Males are smaller before age 50 days and larger thereafter, which becomes less prominent after 200 days. [5]