The white-ankled mouse (''Peromyscus pectoralis'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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 ...

in the family

Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At almost 608 species, it is the second-largest family of mammals, and has m ...

. It is found in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

and in

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

and

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. The white-ankled mouse is commonly found in coexistence with the

brush mouse The brush mouse (''Peromyscus boylii'') is a species of rodent in the family Cricetidae. It is found in mountainous areas of Mexico and the western United States at altitudes over . Description The brush mouse is medium-sized, with small ears a ...

and

Texas mouse The Texas mouse (''Peromyscus attwateri'') is a species of rodent in the family Cricetidae. It is found in Arkansas, Kansas, Missouri, Oklahoma, and Texas in the United States. This species is named in honor of Henry Philemon Attwater. Descrip ...

(''P. boylii'' and ''P. attaweri'', respectively). Often, the sympatric overlap in characteristics between these species makes it difficult to identify a specific species. The most distinguishing feature of the white-ankled mouse, and the one most used to identify the species, is the

baculum The baculum (also penis bone, penile bone, or ''os penis'', ''os genitale'' or ''os priapi'') is a bone found in the penis of many placental mammals. It is absent from the human penis, but present in the penises of some primates, such as the ...

of males (Hooper 1958). The tip of the white-ankled mouse's baculum is long and cartilaginous, whereas the tips of brush and Texas mice are short and rounded (Clark 1952 and Hooper 1958).

Description

White-ankled mice have three distinct

pelage Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily #Guard hair, guard hair on top and thick #Down hair, underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as ...

s in their

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis, ...

s: juvenile, subadult, and adult. Two molt phases (post-juvenile and post-subadult) are necessary for the distinct pelages in each phase of their lives (Hoffmeister 1951). In Texas, the white-ankled mouse differs from the Texas mouse by having shorter hind feet, white ankles, paler color, and a more defined bicolor tail. The white-ankled mouse differs from the Brush mouse by having smaller

molar teeth The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

, white ankles, and shorter hair on the end of the tail (Clark 1953 and Hooper 1958).

Distribution and habitat

Because of the physical similarities between the white-ankled mouse and other mice species, the white-ankled mouse is often misidentified. In New Mexico, for example, many of the distribution ranges of the white-ankled mouse were based on misidentified museum specimens. Upon both further review of these specimens and an experiment involving live traps, the actual distribution of the white-ankled mouse in New Mexico was expanded by 225 km north-northwest (Geluso 2004). When studying the

microhabitats In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

of these coexisting mice, it was discovered that the Texas mouse utilizes trees and the white-ankled mouse does not (Etheredge 1989). In an experiment that removed the Texas mice from these cohabitated microhabitats, the white-ankled mice still did not use the trees. These findings suggest the microhabitats on the white-ankled mouse are inherently selected rather than a result of

interspecific competition Interspecific competition, in ecology, is a form of competition in which individuals of ''different'' species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with mutualism, a type of symbiosis. ...

(Mullican 1990). The white-ankled mouse is partial to rocky and bushy terrains within a variety of habitats: deserts, grasslands and woodlands(Kilpatrick 1971 ).

Diet

White-ankled mice have been known to feed on a variety of seeds, including hackberries, acorns, juniper berries, and cactus fruit (Davis 1966 and Alvarex 1963).

References

* Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 ''in'' Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore. * Alavrez, T. 1963. Mammals of Tamaulipas, Mexico. Univ. Kansas Publ., Mus. Nat. Hist. 14:363-473. * Clark, W. K. 1952. Isolating mechanisms, competition, and geographic variation of the Peromyscus boylei group in Oklahoma and Texas. Unpublished Ph.D. dissertation, Univ. Texas, 102 pp. * Davis, W.B. 1966. The mammals of Texas. Bull. Texas Game and Fish Comm. 41:5-267 * Etheredge, D.R., M.D. Engstrom, and R. C. Stone. 1989. Habitat discrimination between sympatric populations of Peromyscus attwateri and Peromyscus pectoralis in west-central Texas. Journal of Mammalogy, 70:300-307. * Geluso, Keith.
Distribution of the white-ankled mouse (Peromyscus pectoralis) in New Mexico
" The Southwestern Naturalist 49.2 (2004): 283–288. * Hoffmeister, D. F. 1951. A taxonomic and evolutionary study of the pinon mouse Peromyscus truei. Illinois Biol. Monogr. 21:1-104. * Hooper, E.T. 1958
The male phallus in mice of the genus Peromyscus
Misc. Publ. Mus. Zool., Univ. Michigan 105:1-24 * Kilpatrick, C. W. 1971, Distribution of the brush mouse. Permomyscus boylii, and the encinal mouse, Permoyscus pectoralis, in north-central Texas. Southwestern Nat. 16: 209-220 * Mullican, Tim R., and John T. Baccus. "Horizontal and vertical movements of the white-ankled mouse (Peromyscus pectoralis) in central Texas." Journal of mammalogy (1990): 378–381. {{Taxonbar, from=Q947078 Peromyscus Rodents of Mexico Rodents of the United States Mammals described in 1904 Taxonomy articles created by Polbot