| Cavia | |
|---|---|
 | |
| Cavia aperea, or Brazilian guinea pig | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Caviidae |
| Subfamily: | Caviinae |
| Genus: | Cavia Pallas, 1766[1] |
| Type species | |
| Cavia cobaya[1] | |
| Species | |
Cavia is agenus in the subfamilyCaviinae that contains therodents commonly known as theguinea pigs orcavies.[1] The best-knownspecies in this genus is the domestic guinea pig,Cavia porcellus, a meat animal inSouth America and a common household pet outside that continent.
The true guinea pigs are medium-sized rodents. They reach a head-body length of 20 to 35 centimeters (8 to 14 inches) and a weight of 500 to a maximum of 1,000 grams. The largest species of the genus is thegreater guinea pig (Cavia magna). The species are very similar in habit and appearance, the long and relatively rough fur is usually grayish or brown to reddish-brown in color. The coloring can be variable, especially in species with a large distribution area and several subspecies.
The head is relatively large in relation to the body, the eyes are large and the ears are small. The legs are short and strong, the front feet have four toes and the hind feet have three, all of which end in sharp claws, the middle one being the longest.[2][3] All species of the genus are also tailless.[4]
Guinea pigs have a typical rodent dentition withincisors (incisivi) and a gap between the teeth (diastema). In both the upper and lower jaws, there is onepremolar and threemolars in each half. Overall, they have a set of 20 teeth, like all guinea pigs.[5] The teeth arehypsodont like all species of guinea pigs and converge towards the front.[4] The crowns are prismatic and the teeth grow throughout life.[5] In contrast to theyellow-toothed cavies (Galea), the teeth are white in colour.[5]
The jaws of all guinea pigs arehystricomorphous ("porcupine-like"): the angular process growing from the rear end of the lower jaw is not in line with the rest of the jaw, as is the case with other rodents with asciuromorphous ("squirrel-like") jaw structure, but is angled sideways. Themasseter muscle, a jaw muscle, runs partially through theinfraorbital foramen, which is correspondingly enlarged; moreover, like all representatives of theHystricognathi, they lack the infraorbital plate.[5] The species of true guinea pigs can be regarded as comparatively primitive in terms of skull structure. They have only a slight interorbital constriction of the skull, pan elongated paroccipital process of theoccipital bone, a relatively shorthard palate and enlargedtympanic cavity.[5] The skulls of themountain cavies correspond to those of the true guinea pigs, but are significantly more compact and rounded.[5]
Cavia is classified in order Rodentia, although there was once a minority belief in the scientific community that evidence frommitochondrial DNA and proteins suggested theHystricognathi might belong to a differentevolutionary offshoot, and therefore a different order.[6] If this had been so, it would have been an example ofconvergent evolution. However, this uncertainty is largely of historical interest, as abundant molecular genetic evidence now conclusively supports classification ofCavia as rodents.[7][8] This evidence includes draft genome sequences ofCavia porcellus and several other rodents.[9]
Historically, there has been little consensus in regard to the number ofCavia forms and their taxonomic affiliations. Morphological characters differentiating betweenCavia species are limited and levels of inter- and intraspecific morphologic variation have not been well documented, thus, interpretations have varied and resulted in very different taxonomic conclusions. Three scientists disagreed on the number of species, Tate (1935) recognized 11 species, while Cabrera (1961) recognized seven, and Huckinghaus (1961) recognized only three. Recent scientific compilations have generally followed either Cabrera or Huckinghaus.[10]
At least five wild species of guinea pig are recognised, in addition to the domestic form:
Some authors also recognise the following additional species:
In addition, four fossil species have been identified:[12]
{{cite web}}: CS1 maint: archived copy as title (link) (and references therein)
