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Abrawayaomys ruschiiRuschi's rat

By Alex Popidinski and Tanya Dewey

Geographic Range

Abrawayaomys ruschii is located in southeastern Brazil in the Atlantic forest. This species is known from a small number of specimens, so the extent of its range is not well known. (Pereira, et al., 2008)

Habitat

Abrawayaomys ruschii lives exclusively in the Atlantic forest in southeastern Brazil. The Atlantic forest is a massive forest with many kinds of habitats. Abrawayaomys ruschii has only been found in bamboo forests and lowland rain forests in this area. However, this information is based on few known specimens and could change with additional data. (Tiepolo, 2014)

Physical Description

Ruschi's rats usually weigh between 40 and 65 grams. They are small, with a length range of 115 to 135 mm. Their tails are very long with a range of 85 to 148 mm. Males are typically larger than females in both size and weight. There is a distinguishing tuft of hair at the tip of their tails, which is unusual for rat species. Unlike most other rats, the hairs on their body are fairly spiny, with the spines becoming more prevalent as you move toward the tail. Fur color is normally brown or grey and they have short rostra. (Cerboncini, et al., 2014; Pardinas, et al., 2009)

  • Sexual Dimorphism
  • male larger
  • Range mass
    40 to 65 g
    1.41 to 2.29 oz
  • Range length
    200 to 283 mm
    7.87 to 11.14 in

Reproduction

Ruschi's rats have not been observed extensively in the wild, so there is little information on behavior. Many sigmodontine rodents are promiscuous or polygamous and will mate with any number of individuals. (Cerboncini, et al., 2014; Steinmann, et al., 2008)

Ruschi's rats have not been extensively studied in the wild and there is little information on reproduction. (Cerboncini, et al., 2014; Hull and Dominguez, 207)

  • Breeding interval
    Breeding interval in Ruschi's rats is not reported in the literature.
  • Breeding season
    Breeding season of Ruschi's rats is not reported in the literature.

Ruschi's rats have not been observed in the wild and there is little information on parental care. In general, sigmodontine rodent females care for their young exclusively through gestation and lactation and young become independent soon after weaning. (Steinmann, et al., 2008)

  • Parental Investment
  • altricial
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female

Lifespan/Longevity

Longevity in Ruschi's rats is unknown at this point. Captive individuals have survived from 3 to 5 years. (Pardinas, et al., 2009)

  • Range lifespan
    Status: captivity
    5 (high) years
  • Typical lifespan
    Status: captivity
    3 to 5 years

Behavior

Ruschi's rats have not been studied extensively in the wild and little is known of their behavior.

  • Key Behaviors
  • terricolous
  • motile

Home Range

Home range in Ruschi's rats is not reported in the literature.

Communication and Perception

Most rodents use auditory, visual, tactile, and chemical signals in perception and communication, so it is likely that Ruschi's rats do as well. (Hull and Dominguez, 207; Pereira, et al., 2008)

Food Habits

Ruschi's rats prefer a diet of fruits, seeds, and nuts while in captivity. Whether this reflects what they eat in the wild is unknown. (Pardinas, et al., 2009)

  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit

Predation

Ruschi's rats have a unique spiny pelage that may deter predation to some extent. No predators are reported in the literature. (Pardinas, et al., 2009)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Ruschi's rats are poorly studied and little is known of their impact on the ecosystems in which they live.

Economic Importance for Humans: Positive

There are no known positive impacts of Ruschi's rats on humans, but little is known of their ecology and behavior.

Economic Importance for Humans: Negative

There are no known negative impacts of Ruschi's rats on humans.

Conservation Status

While Abrawayaomys ruschii lives in an area under constant threat of deforestation and has not been studied extensively in the wild. However, individuals have been found across a relatively large range. The IUCN has placed this species in the least concern category. Other conservation organizations have not given the species any recognition as it is still relatively unstudied. (Pardinas, et al., 2008)

Contributors

Alex Popidinski (author), University of St. Francis, Tanya Dewey (author, editor), University of Michigan-Ann Arbor, William Bromer (editor), University of St. Francis.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Cerboncini, R., T. Zanata, W. Cunha, A. Rorato, A. Calefi, M. Sbeghen, . Macagnan, K. Abreu, M. Ono, F. Passos. 2014. Distribution extension of Abrawayaomys ruschii Cunha and Cruz, 1979 (Rodentia: Cricetidae) with the first records in the state of Paraná, southern Brazil. Check List, 10(3): 660-662.

Hull, E., J. Dominguez. 207. SEXUAL BEHAVIOR IN MALE RODENTS. NIHPA Manuscripts, 52(1): 45-55. Accessed November 06, 2014 at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1952538/.

Pardinas, U., P. Teta, A. Percequillo. 2008. "Abrawayaomys ruschii" (On-line). The UNCN Red List of Threatened Species. Accessed November 06, 2014 at http://www.iucnredlist.org/details/16/0.

Pardinas, U., P. Teta, G. D'Ella. 2009. Taxonomy and distribution of Abrawayaomys (Rodentia: Cricetidae), an Atlantic Forest endemic with the description of a new species. Zootaxa, 2128: 39-60.

Pereira, L., L. Geise, . Adams, R. Cerqueira. 2008. Abrawayaomys ruschii Cunha & Cross, 1979 (Rodentia, Cricetidae) in the State of Rio de Janeiro, Brazil. SciELO, 48: 5.

Poor, A. 2005. "Sigmodontinae South American rats and mice" (On-line). Animal Diversity Web. Accessed November 06, 2014 at http://animaldiversity.ummz.umich.edu/accounts/Sigmodontinae/.

Steinmann, A., J. Pritotto, J. Polop. 2008. Territorial behaviour in corn mice, Calomys musculinus (Muridae: Sigmodontinae), with regard to mating system. J Ethol, 27: 51-58. Accessed November 06, 2014 at http://voxpopuliunrc.org/ecopaisaje/archivos/2009%20Steinmann%20et%20al%202009-%20Territorial%20behaviour%20in%20corn%20mice,%20Calomys%20musculinus-J%20Ethol.pdf.

Testoni, A., S. Althoff, A. Nascimento, . Steiner-Souza, . Sbalqueiro. 2010. Description of the karyotype of Rhagomys rufescens Thomas, 1886 (Rodentia, Sigmodontinae) from Southern Brazil Atlantic forest. SciELO, 33: 3.

Tiepolo, G. 2014. "The Atlantic Forest harbors a range of biological diversity similar to that of the Amazon." (On-line). The Nature Conservancy. Accessed October 06, 2014 at http://www.nature.org/ourinitiatives/regions/southamerica/brazil/placesweprotect/atlantic-forest.xml.

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