Hydrochoerinae is a subfamily of

Caviidae Caviidae, the cavy family, is composed of rodents native to South America and includes the domestic guinea pig, wild cavies, and the largest living rodent, the capybara. They are found across South America in open areas from moist savanna to tho ...

, consisting of two living genera, ''

Hydrochoerus The genus ''Hydrochoerus'' contains two living and two extinct species of rodents from South America, the Caribbean island of Grenada, California and Panama. Capybaras are the largest living rodents in the world. The genus name is derived from t ...

'', the capybaras, and ''

Kerodon The genus ''Kerodon'' (vernacular name Mocos; Rock Cavies) contains two species of South American rock cavies, related to capybaras and guinea pigs. They are found in semiarid regions of northeast Brazil known as the Caatinga. This area has a roc ...

'', the rock cavies. In addition, a number of extinct genera related to capybaras should also be placed in this subfamily. The taxonomy of Hydrochoerinae is confused because, until 2005, living capybaras and their extinct relatives were placed in their own family, Hydrochoeridae.McKenna, Malcolm C., and Bell, Susan K. 1997. ''Classification of Mammals Above the Species Level.'' Columbia University Press, New York, 631 pp. Recent molecular phylogenetic studies recognize a close relationship between ''Hydrochoerus'' and ''Kerodon'', supporting placement of both genera in a subfamily of

. Paleontological classifications have yet to incorporate this new taxonomy, and continue to use Hydrochoeridae for all capybaras, while using Hydrochoerinae for the living genus and its closest fossil relatives such as ''

Neochoerus ''Neochoerus'' ("new hog") is an extinct genus of rodent closely related to the living capybara. Fossil remains of ''Neochoerus'' have been found through North America (México and United States) and South America in Boyacá, Colombia C ...

''. The taxonomy of fossil hydrochoerines is also in a state of flux. In recent years, the diversity of fossil hydrochoerines has been substantially reduced. This is largely due to the recognition that capybara molar teeth show strong variation in shape over the life of an individual. In one instance, material once referred to four genera and seven species on the basis of differences in molar shape is now thought to represent differently aged individuals of a single species, ''Cardiatherium paranense''.

References

Cavies Mammal subfamilies Taxa named by John Edward Gray {{rodent-stub