The Mexican pygmy mouse (''Baiomys musculus'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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

native to

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

Taxonomy

In 2021 it was determined that seven of the eight recognized

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

formerly considered part of ''Baiomys musculus'' should instead belong to ''Baiomys brunneus''. The

Trans-Mexican Volcanic Belt The Trans-Mexican Volcanic Belt (), also known as the Transvolcanic Belt and locally as the (''Snowy Mountain Range''), is an active volcanic belt that covers central-southern Mexico. Several of its highest peaks have snow all year long, and dur ...

and the

Balsas River The Balsas River (Spanish Río Balsas, also locally known as the Mezcala River, or Atoyac River) is a major river of south-central Mexico. The basin flows through the states of Guerrero, México, Morelos, and Puebla. Downstream of Ciudad Alt ...

, form a barrier between ''Baiomys musculus'' to the west and ''Baiomys brunneus'' to the east. This species, as well as ''B. musculus'', are likely more basal within ''Baiomys'' than the

northern pygmy mouse The northern pygmy mouse (''Baiomys taylori'') is a species of rodent in the family Cricetidae. It is known as ''ratón-pigmeo norteño'' in the Spanish-speaking areas of its range. It is found in Mexico and the United States. It is the smallest ...

, since they moreso resemble fossil species. This species has no accepted subspecies.

Description

The hair of this species tends to be olive-brown to dark brown on top and lighter whitish to grayish on the bottom. The body length of this species is , with a tail. It is larger on average than ''B. brunneus''. Uncharacteristically of other members in the family Cricetidae they have 14 cheek teeth instead of 12.

Ecology

Similar to ''Baiomys brunneus'', this species likely prefers to live in grasslands. They have been found in

owl pellet A pellet, in ornithology, is the mass of undigested parts of a bird's food that some bird species occasionally regurgitate. The contents of a bird's pellet depend on its diet, but can include the exoskeletons of insects, indigestible plant m ...

s, and are likely preyed upon by

birds of prey Birds of prey or predatory birds, also known as (although not the same as) raptors, are hypercarnivorous bird species that actively predation, hunt and feed on other vertebrates (mainly mammals, reptiles and smaller birds). In addition to speed ...

and small mammals. They are active in the afternoon and early evening. They feed on nuts, leaves, seeds, and fruits.

Range

This species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Mexico. It lives in the

states State most commonly refers to: * State (polity), a centralized political organization that regulates law and society within a territory **Sovereign state, a sovereign polity in international law, commonly referred to as a country **Nation state, a ...

Michoacán Michoacán, formally Michoacán de Ocampo, officially the Free and Sovereign State of Michoacán de Ocampo, is one of the 31 states which, together with Mexico City, compose the Political divisions of Mexico, Federal Entities of Mexico. The stat ...

Colima Colima, officially the Free and Sovereign State of Colima, is among the 31 states that make up the 32 Federal Entities of Mexico. It shares its name with its capital and main city, Colima. Colima is a small state of western Mexico on the cen ...

, southern and central

Jalisco Jalisco, officially the Free and Sovereign State of Jalisco, is one of the 31 states which, along with Mexico City, comprise the 32 Political divisions of Mexico, Federal Entities of Mexico. It is located in western Mexico and is bordered by s ...

, and southern

Nayarit Nayarit, officially the Free and Sovereign State of Nayarit, is one of the 31 states that, along with Mexico City, comprise the Political divisions of Mexico, Federal Entities of Mexico. It is divided in Municipalities of Nayarit, 20 municipalit ...

References

Mammals described in 1892 Taxa named by Clinton Hart Merriam Rodents of Mexico Endemic mammals of Mexico Baiomys {{Cricetidae-stub