''Galea'' is a genus of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

s of the family

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 th ...

. Five extant species are known, found in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

and

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. They are: * Southern highland yellow-toothed cavy ('' G. comes'') *

Brazilian yellow-toothed cavy The Brazilian yellow-toothed cavy (''Galea flavidens'') is a cavy species from South America. It is found in Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South ...

(''G. flavidens'') * Lowland yellow-toothed cavy ('' G. leucoblephara'') *

Common yellow-toothed cavy The common yellow-toothed cavy (''Galea musteloides'') is a species of rodent in the family Caviidae, closely related to the domesticated guinea pig. It is found in Argentina, Bolivia, Chile, and Peru , image_flag = Flag of Pe ...

(''G. musteloides'') **

Muenster yellow-toothed cavy The Muenster yellow-toothed cavy (''Galea monasteriensis'') is a species of rodent in the family Caviidae. It is known only from one location in Valle Hermoso in the Bolivian Andes, at an elevation of 2557 m. Specimens from this location were ...

(''G. m. monasteriensis'') * Spix's yellow-toothed cavy (''G. spixii'') ''Galea'' has until recently been considered to have only three species; the Muenster yellow-toothed cavy was only described in 2004. ''G. flavidens'' is monotypic and ''G. musteloides'' and ''G. spixii'' are polytypic. ''Galea'' is in the family

and its members are described as cavies; they have sometimes also been called "guinea pigs". Cavies are widespread throughout South America. The high diversity of habitats of different species is paralleled by a high diversity of social organizations. Species differences between habitats and reproduction may shed light on evolutionary history. ''Galea'' breeds at multiple times of year that are not strongly constrained by food availability or climate. The gestation period is 48 days and litter size is 2 to 4, both less than those of the

guinea pig The guinea pig or domestic guinea pig (''Cavia porcellus''), also known as the cavy or domestic cavy (), is a species of rodent belonging to the genus ''Cavia'' in the family Caviidae. Breeders tend to use the word ''cavy'' to describe the ani ...

. Placental development in ''Galea'' is very similar to that of the guinea pig. ''Galea'' species usually have smaller body size but the relative sizes of their

testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...

and

epididymis The epididymis (; plural: epididymides or ) is a tube that connects a testicle to a vas deferens in the male reproductive system. It is a single, narrow, tightly-coiled tube in adult humans, in length. It serves as an interconnection between the ...

are twice those of ''

Cavia ''Cavia'' is a genus in the subfamily Caviinae that contains the rodents commonly known as guinea pigs or cavies. The best-known species in this genus is the domestic guinea pig, ''Cavia porcellus'', a meat animal in South America and a common ...

'' species. In the majority of cases, the

acrosome The acrosome is an organelle that develops over the anterior (front) half of the head in the spermatozoa (sperm cells) of many animals including humans. It is a cap-like structure derived from the Golgi apparatus. In placental mammals the acrosome ...

s of ''Galea'' sperm are smooth in outline, and only occasionally are degenerate forms present or are the acrosomes absent. In ''Galea'', the

spermatozoa A spermatozoon (; also spelled spermatozoön; ; ) is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromosomes, ...

of the epididymis are always single-cell whereas those of ''Cavia'' are agglutinated in the form of

rouleaux Rouleaux (singular is rouleau) are stacks or aggregations of red blood cells (RBCs) that form because of the unique discoid shape of the cells in vertebrates. The flat surface of the discoid RBCs gives them a large surface area to make contact wi ...

. ''Galea'' spermatozoa swim more slowly than those of ''Cavia''. While some ''Galea'' species are

promiscuous Promiscuity is the practice of engaging in sexual activity frequently with different Sexual partner, partners or being indiscriminate in the choice of sexual partners. The term can carry a moral judgment. A common example of behavior viewed as pro ...

—for example ''G. musteloides''—''Cavia'' exhibits

polygynous Polygyny (; from Neoclassical Greek πολυγυνία (); ) is the most common and accepted form of polygamy around the world, entailing the marriage of a man with several women. Incidence Polygyny is more widespread in Africa than in any ...

behavior, which means that males are selected for aggression so that multiple matings will be prohibited.

References

Cavies Rodent genera Taxa named by Franz Meyen {{rodent-stub