Pseudo-penis

A pseudo-penis is a term used of any structure found on an animal that while superficially appearing to be a penis, is derived from a different developmental path.

Mammals

In mammals, all intact developmentally typical males have a penis, but the clitoris in the females of the following species is sufficiently enlarged that it is usually termed a pseudo-penis: spotted hyena,^[1] squirrel monkey, lemur, juvenile fossa^[2] and binturong.^[3] The enlarged clitoris in the fossa is supported by an os clitoridis, a bone similar to the os penis found in most mammals.^[2] However, the fossa's os clitoridis and pseudo-penis shrink as the juvenile female grows, unlike that of other pseudo-penis species.^[2] The labia of the spider monkey are elongated and may be similarly confused during display. Elongated labia are also observed in humans.

The mammalian pseudo-penis appears to be simply for display, although the hyena is an exception: the female hyena additionally uses her pseudo-penis for urination, copulation, and childbirth. In addition, this makes it difficult for males to mate without the full cooperation of females, which helps the female-dominated society of spotted hyenas to eliminate forced sex. ^[4]

Birds

A notable example of a bird with a pseudo-penis is the Red-billed Buffalo Weaver, which can still mate even if its pseudo-penis is disabled. ^[5] Only 3% of bird species have a phallus: the common urogenital arrangement for both males and females is the cloaca, through which all elimination and reproduction (via juxtaposed cloacas) occurs, but certain bird species, particularly ratites, screamers, waterfowl, and cracids (a family of arboreal galliformes) exhibit a phallus in the male, a structure derived from the internal cloacal wall which is generally associated with sperm competition. Popularised species include the Ruddy duck and the Argentine lake duck. The corkscrew-shaped phallus of the latter can approach 16 inches in length.^[6]

References

1. ^ ADW: Crocuta crocuta: Information
2. ^ ^{a b c} Goodman S (2009). "Family Eupleridae (Madagascar Carnivores)". In Wilson D & Mittermeier R. Handbook of the Mammals of the World. Volume 1: Carnivores. Barcelona: Lynx Edicions. ISBN 978-84-96553-49-1. http://www.lynxeds.com/hmw/species-accounts/hmw-1-species-accounts-red-panda-ailurus-fulgens. 
3. ^ http://www.conservatorscenter.org/speciesinfo/bint.pdf
4. ^ Hyenas Encourage Sex With Strangers to Prevent Incest
5. ^ Avian Reproduction
6. ^ Evolutionary Oddities: Duck Sex Organ, Lizard Tongue