Brazilian shrew mouse Temporal range: Pleistocene – Recent | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Cricetidae |
Subfamily: | Sigmodontinae |
Tribe: | Akodontini |
Genus: | Blarinomys Thomas, 1896 |
Species: | B. breviceps |
Binomial name | |
Blarinomys breviceps (Winge, 1888) | |
The Brazilian shrew mouse (Blarinomys breviceps), [2] also known as the blarinine akodont, [3] is a rodent in the tribe Akodontini from the Atlantic Forest of eastern and southeastern Brazil. [1] It is the only species in the genus Blarinomys. [3] Phylogenetic analysis suggest that there are two clear geographical clades, a northeastern and southeastern. [4]
The appearance of the Brazilian shrew mouse is often compared to that of small insectivorous shrews or moles with small, reduced eyes, short ears and tail, and short, soft fur. [5] Its mole-like appearance contributes to its ability to be differentiated from other rodents in its Neotropical habitat. [6] Overall, its specialized body structure lends itself to the animal's subterranean life, with broad forefeet and large claws for digging. [7] It has a long snout that is used to find insects in the ground and highly developed jaw muscles that help to close the mouth quickly, as to avoid swallowing dirt. [5] The species has demonstrated sexual dimorphism in that females are usually slightly larger than males. [6]
The average lifespan of the Brazilian shrew mouse is unknown, as they are difficult to find. Captive specimens tend to refuse food and die shortly after capture. [6] It is generally assumed that the species' lifespan is similar to other Sigmodontinae rodents, which is typically less than one year. [8] [ page needed ]
Very little is known about the diet of B. breviceps, however it is assumed to be primarily insectivorous. When studied in captivity, many specimens refuse food and die within a few days. However, some captive organisms have been shown to eat a variety of insects including crickets, moths and butterflies, and roaches. Overall, they tend to refuse other food sources such as fruits or seeds. [6]
According to the International Union for Conservation of Nature's Red List of Endangered Species, the Brazilian shrew mouse is considered of least concern. [1] However, some experts suggest that since the species is so difficult to find, data is insufficient to confidently label their conservation status. [9]
Akodontini is the second most speciose rodent tribe of the subfamily Sigmodontinae. It includes at least 106 living species in 19 genera and is distributed mainly in the southern half of South America, with only two genera extending into Guyana (Podoxymys) and Venezuela (Necromys). It also includes genera previously placed in tribe Scapteromyini. The following genera are now generally recognized:
The New World rats and mice are a group of related rodents found in North and South America. They are extremely diverse in appearance and ecology, ranging from the tiny Baiomys to the large Kunsia. They represent one of the few examples of muroid rodents in North America, and the only example of muroid rodents to have made it into South America.
Bibimys is a genus of new world rats. Commonly known as the crimson-nosed rats, there are three species:
The cursor grass mouse, or cursorial akodont, is a sigmodontine rodent from South America.
Oligoryzomys nigripes, also known as the black-footed colilargo or the black-footed pygmy rice rat, is a rodent in the genus Oligoryzomys of family Cricetidae. Oligoryzomys nigripes is a species that has been further divided into different sister taxa throughout history. It is found in different countries in South America. It is a large species with long ears, dark yellow to dark brown upperparts, sharply delimited from the whitish underparts, and often a pink girdle on the chest. This species of rat spends much of its life among the trees. The karyotype is 2n = 62, FNa = 78–82.
The lesser Wilfred's mouse is a species of South American rodents of the family Cricetidae. It was first described by Wilfred H. Osgood under the name Thomasomys pictipes, then into the genus Wilfredomys, and now known as Juliomys pictipes. The lesser Wilfred's mouse is endemic to northeastern Argentina and southeastern Brazil. Its physical appearance ranges from dark brown to light orange coloration and the typical size is small to medium. This species is arboreal, spending most of its time trees and living in the local forests at altitudes from sea level to 2000 m. Currently, this species is listed as Least Concern by the IUCN, but, threats include livestock farming, ranching, and wood harvesting.
Lundomys molitor, also known as Lund's amphibious rat or the greater marsh rat, is a semiaquatic rat species from southeastern South America.
Pseudoryzomys simplex, also known as the Brazilian false rice rat or false oryzomys, is a species of rodent in the family Cricetidae from south-central South America. It is found in lowland palm savanna and thorn scrub habitats. It is a medium-sized species, weighing about 50 grams (1.8 oz), with gray–brown fur, long and narrow hindfeet, and a tail that is about as long as the head and body. The IUCN has assessed its conservation status as being of least concern, although almost nothing is known about its diet or reproduction.
Rhipidomys is a genus of rodents in the family Cricetidae, The following 25 species of climbing mouse species are currently recognised:
Abrothrix longipilis, also known as the long-haired grass mouse or long-haired akodont, is a species of rodent in the family Cricetidae. It is endemic to central Argentina and Chile. Until 2014 it was thought that the species extended into southern Chile and Argentine Patagonia but these populations are now proposed to belong to closely related species named Abrothrix hirta.
Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of the family Cricetidae. It includes about 120 species in about thirty genera, distributed from the eastern United States to the southernmost parts of South America, including many offshore islands. It is part of the clade Oryzomyalia, which includes most of the South American Sigmodontinae.
Cerradomys is a genus of oryzomyine rodents from eastern Bolivia, Paraguay, and central Brazil found in cerrado, Caatinga and Gran Chaco habitats.
Oligoryzomys rupestris is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is known only from eastern Brazil, where it has been found in several localities in the campos rupestres montane savanna ecoregion. This is a small Oligoryzomys species with a gray head, a yellow-brown back and gray belly and tail. Of the two karyotypic forms described by Silva & Yonenaga-Yassuda in 1998, species 1 is probably identical to O. rupestris, while the other is closely related. Its karyotype has 2n = 46 and FNa = 52.
Carletonomys cailoi is an extinct rodent from the Pleistocene (Ensenadan) of Buenos Aires Province, Argentina. Although known only from a single maxilla with the first molar, its features are so distinctive that it is placed in its own genus, Carletonomys. Discovered in 1998 and formally described in 2008, it is part of a well-defined group of oryzomyine rodents that also includes Holochilus, Noronhomys, Lundomys, and Pseudoryzomys. This group is characterized by progressive semiaquatic specializations and a reduction in the complexity of molar morphology.
Juliomys anoblepas is a rodent in the genus Juliomys of the subfamily Sigmodontinae known from a single broken skull. The specimen was collected by Peter Wilhelm Lund in the caves of Lagoa Santa, Minas Gerais, Brazil, in the first half of the 19th century and described by Herluf Winge in 1888 as Calomys anoblepas. The species remained unstudied and its affinities unclear until 2011, when it was recognized as a member of the genus Juliomys, which includes three other species from southern Brazil and nearby Argentina and Paraguay. J. anoblepas is probably a separate extinct species of the genus, which is no longer found at Lagoa Santa.
In anatomy, posterolateral palatal pits are gaps at the sides of the back of the bony palate, near the last molars. Posterolateral palatal pits are present, in various degrees of development, in several members of the rodent family Cricetidae. Many members of the family lack them or have only simple pits, but Arvicolinae and Oryzomyini have more highly developed posterolateral palatal pits. Posterolateral palatal pits are also present in some other rodents, including Glis, Jaculus, Hystrix, Abrocoma, Ctenomys, Chinchilla, and Lagidium.
In rodent anatomy, the zygomatic plate is a bony plate derived from the flattened front part of the zygomatic arch (cheekbone). At the back, it connects to the front (maxillary) root of the zygomatic arch, and at the top it is connected to the rest of the skull via the antorbital bridge. It is part of the maxillary bone, or upper jaw, which also contains the upper cheekteeth. Primitively, rodents have a nearly horizontal zygomatic plate. In association with specializations in zygomasseteric system, several distinct morphologies have developed across the order.
In mammals, ungual tufts are tufts of hairs at the base of claws of the forefeet and hindfeet. Their presence has been used as a character in cladistic studies of the Cricetidae, a large family of rodents.
Juliomys is a genus of South American rodents of the family Cricetidae. Five species are known, all found in Argentina and Brazil. They are as follows:
Rhagomys is a genus of South American rodents in the tribe Thomasomyini of the family Cricetidae. Two species separated by about 3100 km are known, from southeast Peru and Bolivia east of the Andes, and in the Atlantic Forest of southeast Brazil. An undetermined species of Rhagomys has also been reported from Mato Grosso in central Brazil. The species are as follows: