Ucucha oldfield mouse
Encyclopedia
Thomasomys ucucha, also known as the Ucucha Thomasomys, is a rodent
in the genus Thomasomys
of the family Cricetidae
. Found only in the Cordillera Oriental of Ecuador, a mountain range, it lives in forests and grasslands at 3380 to 3720 m (11,090 to 12,200 ft) above sea level. It may occur with seven other species of Thomasomys. First collected in 1903, Thomasomys ucucha was formally described in 2003 and most closely resembles T. hylophilus, which occurs further to the north. Habitat destruction
may threaten T. ucucha, so that it is listed as "Vulnerable
" on the IUCN Red List
.
Medium-sized, dark-furred, and long-tailed, Thomasomys ucucha can be distinguished from all other species of Thomasomys by its large, broad, procumbent upper incisor
s. Head and body length is 94 to 119 mm (3.7 to 4.7 in) and body mass is 24 to 46 g (0.8 to 1.6 oz). The tail is scarcely furred. The front part of the skull is flat, short, and broad. The incisive foramina, openings at the front of the palate
, are short, and the palate itself is broad and smooth. The root of the lower incisor is contained in a prominent capsular process
.
, Ecuador, by L. Söderström. It was not found again until Robert S. Voss of the American Museum of Natural History
collected a total of forty-three specimens at nearby Papallacta
, Napo Province
, in 1978 and 1980. Papallacta is in a remote area that is difficult to access, and the mammal fauna of the region remains poorly known. In 2003, he formally described the animal as a new species, Thomasomys ucucha, in a publication in American Museum Novitates
in which he also reviewed the mammal fauna of Papallacta. The generic name, Thomasomys
, honors English zoologist Oldfield Thomas
, who named about 2,900 taxa
of mammals, and the specific name, ucucha, is the local Quechua
word for "mouse". T. ucucha most closely resembles T. hylophilus, which is found further north in Colombia and Venezuela. Both are members of Thomasomys, a diverse genus that occurs in the northern Andes, from Bolivia to Venezuela. Together with Rhipidomys
and a few other, smaller genera, Thomasomys forms the tribe Thomasomyini, which includes over fifty species found in South America and Panama. Thomasomyini in turn is part of the subfamily Sigmodontinae
of the family Cricetidae
, along with hundreds of other species of mainly small rodents.
s (bones of the centers of the hand and feet) of the hands and feet are covered with dark hairs, but the ungual tufts at the bases of the claws consist of longer, gray hairs. The fifth digit of the foot is long, with the tip of its claw almost reaching the base of the claw of the fourth digit. The tail is dark and hardly furred, except for a pencil of long hairs at the end; some animals have a white tail tip. Females have six mammae. In thirty-six specimens, head and body length is 94 to 119 mm (3.7 to 4.7 in), averaging 110 mm (4.3 in); tail length is 122 to 151 mm (4.8 to 5.9 in), averaging 140 mm (5.5 in); hindfoot length is 26 to 30 mm (1 to 1.2 in), averaging 28 mm (1.1 in); ear length is 17 to 20 mm (0.7 to 0.8 in), averaging 18 mm (0.7 in); and weight is 24 to 46 g (0.8 to 1.6 oz), averaging 36 g (1.3 oz).
The front (rostral) part of the skull
is short—shorter and broader than in T. hylophilus—and flat and the notches in the zygomatic plate
s at the sides are poorly developed. The plates themselves are broad. The zygomatic arch
es (cheekbones) spread broadly and are rounded in shape. The narrow interorbital region
(between the eyes) is hourglass-shaped. The braincase is robust.
The incisive foramina
, which perforate the palate
between the incisor
s and the molars
, are short and do not reach near the first molars; they are longer in T. hylophilus. They are widest where the premaxilla
ry and maxilla
ry bones meet. The palate itself is also short, not extending beyond the third molars, and is broad and lacks ridges or grooves. There are simple posterolateral palatal pits
at the back of the palate, near the third molars. The mesopterygoid fossa, an opening located behind the end of the palate, is broad and its roof is either fully ossified or perforated by small sphenopalatine vacuities
where the presphenoid
and basisphenoid bones meet. An alisphenoid strut
separates two foramina
(openings) at the base of the skull, the buccinator-masticatory foramen and the foramen ovale accessorius. The pattern of grooves and foramina on the head indicates that the circulation of the arteries in the head of T. ucucha follows the primitive pattern. The tegmen tympani, the roof of the tympanic cavity
, overlaps the suspensory process
of the squamosal bone. At the back of the mandible
(lower jaw), there is a capsular process
to receive the root of the lower incisor
, which is absent in T. hylophilus.
The large upper incisors are orthodont, with their cutting edge at about a right angle to the upper molars, and heavily pigmented with orange. Those of T. hylophilus are narrower, less procumbent, and less pigmented. The orthodont upper incisors suffice to distinguish T. ucucha from all other members of the genus but T. australis and T. daphne, which have much shorter and narrower incisors. The left and right molar rows are parallel. The molars are more hypsodont
(high-crowned) than in other Thomasomys. The anterocone, the cusp at the front of the first upper molar, is divided into distinct cuspules at the lingual (inner) and labial (outer) sides by an anteromedian flexus. The accessory ridges on the upper molars, the anterolophs and mesolophs, are less well-developed than in T. hylophilus. The third upper molar is reduced relative to the second, much more so than in T. hylophilus. The lower molars are generally similar to the uppers, but the anteroconid (the equivalent of the anterocone on the first lower molar) is often undivided and the third molar is unreduced.
The glans penis
is rounded, short, and small and is superficially divided into left and right halves by a trough at the top and a ridge at the bottom. Most of the glans is covered with spines, except for an area near the tip.
(high-mountain grassland with shrubs and forest patches) and subalpine rainforest. Most were taken in runways (paths through vegetation made by animals) and a few alongside small streams or on a low tree. Other muroid rodents found at the same places as T. ucucha include two akodontines
(grass mice), Akodon latebricola and Akodon mollis; two ichthyomyines
(water rats), Anotomys leander and Neusticomys monticolus; two oryzomyines
(rice rats), Microryzomys altissimus and M. minutus; the thomasomyine Chilomys instans; and five other species of Thomasomys, T. aureus, T. baeops, T. cinnameus, T. erro, and T. paramorum. Other species have been recorded nearby, and Voss wrote that T. ucucha may occur sympatrically with seven other species of Thomasomys. With Akodon latebricola and Thomasomys erro, T. ucucha is one of three species that are known only from the northeastern Andes of Ecuador.
" by the IUCN because of its small distribution; it may be threatened by the destruction of its habitat for agricultural
purposes, but occurs near two protected area
s.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the genus Thomasomys
Thomasomys
Thomasomys is a genus of rodent in the family Cricetidae, named after British zoologist Oldfield Thomas. It contains the following species:* Anderson's Oldfield Mouse * Apeco Oldfield Mouse...
of the family Cricetidae
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
. Found only in the Cordillera Oriental of Ecuador, a mountain range, it lives in forests and grasslands at 3380 to 3720 m (11,090 to 12,200 ft) above sea level. It may occur with seven other species of Thomasomys. First collected in 1903, Thomasomys ucucha was formally described in 2003 and most closely resembles T. hylophilus, which occurs further to the north. Habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
may threaten T. ucucha, so that it is listed as "Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
" on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
.
Medium-sized, dark-furred, and long-tailed, Thomasomys ucucha can be distinguished from all other species of Thomasomys by its large, broad, procumbent upper incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s. Head and body length is 94 to 119 mm (3.7 to 4.7 in) and body mass is 24 to 46 g (0.8 to 1.6 oz). The tail is scarcely furred. The front part of the skull is flat, short, and broad. The incisive foramina, openings at the front of the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
, are short, and the palate itself is broad and smooth. The root of the lower incisor is contained in a prominent capsular process
Capsular process
In rodents, the capsular process or projection is a bony capsule that contains the root of the lower incisor. It is visible on the labial side of the mandible as a raising in the bone...
.
Taxonomy
The first three specimens of Thomasomys ucucha were collected in 1903 at Tablón in Pichincha ProvincePichincha Province
Pichincha is a province of Ecuador located in the northern sierra region; its capital and largest city is Quito. It is bordered by Imbabura & Esmeraldas to the north, Cotopaxi & Santo Domingo de los Tsáchilas to the south, Napo & Sucumbíos to the east, and Esmeraldas & Santo Domingo de los...
, Ecuador, by L. Söderström. It was not found again until Robert S. Voss of the American Museum of Natural History
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
collected a total of forty-three specimens at nearby Papallacta
Papallacta
Papallacta is a small village in Ecuador located at an altitude of 3,300 m in the Andes just off the Eastern Cordilleras on the road from Quito which leads into the Amazon jungle. The scenic drive from Quito to Papallacta passes through several towns and small villages before ascending to a peak of...
, Napo Province
Napo Province
Napo is a province in Ecuador. Its capital is Tena. The province contains the Napo River. The province is low developed without much industrial presence. The thick rainforest is home to many natives that remain isolated by preference, descendents of those who fled the Spanish invasion in the Andes,...
, in 1978 and 1980. Papallacta is in a remote area that is difficult to access, and the mammal fauna of the region remains poorly known. In 2003, he formally described the animal as a new species, Thomasomys ucucha, in a publication in American Museum Novitates
American Museum Novitates
American Museum Novitates is an academic journal published by the American Museum of Natural History. The journal was founded in 1921....
in which he also reviewed the mammal fauna of Papallacta. The generic name, Thomasomys
Thomasomys
Thomasomys is a genus of rodent in the family Cricetidae, named after British zoologist Oldfield Thomas. It contains the following species:* Anderson's Oldfield Mouse * Apeco Oldfield Mouse...
, honors English zoologist Oldfield Thomas
Oldfield Thomas
Oldfield Thomas FRS was a British zoologist.Thomas worked at the Natural History Museum on mammals, describing about 2,000 new species and sub-species for the first time. He was appointed to the Museum Secretary's office in 1876, transferring to the Zoological Department in 1878...
, who named about 2,900 taxa
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
of mammals, and the specific name, ucucha, is the local Quechua
Quechua languages
Quechua is a Native South American language family and dialect cluster spoken primarily in the Andes of South America, derived from an original common ancestor language, Proto-Quechua. It is the most widely spoken language family of the indigenous peoples of the Americas, with a total of probably...
word for "mouse". T. ucucha most closely resembles T. hylophilus, which is found further north in Colombia and Venezuela. Both are members of Thomasomys, a diverse genus that occurs in the northern Andes, from Bolivia to Venezuela. Together with Rhipidomys
Rhipidomys
Rhipidomys is a genus of rodents in the family Cricetidae, comprising at least 18 species of climbing mouse:* Southern Climbing Mouse * Cariri Climbing Mouse...
and a few other, smaller genera, Thomasomys forms the tribe Thomasomyini, which includes over fifty species found in South America and Panama. Thomasomyini in turn is part of the subfamily Sigmodontinae
Sigmodontinae
The subfamily Sigmodontinae is one of the most diverse groups of mammals. It includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species count...
of the family Cricetidae
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
, along with hundreds of other species of mainly small rodents.
Description
Thomasomys ucucha is a medium-sized Thomasomys with a relatively long tail. The dense, fine, and soft fur is dark brown on the upperparts, changing gradually into the grey underparts. The mystacial vibrissae (whiskers above the mouth) are long and extend beyond the ears when laid back against the head. Sparse short, dark hairs are present on the ears. The digits and metapodialMetapodial
Metapodials are long bones of the hand and feet which connect the digits to the centers. In humans, five are present in each hand and foot....
s (bones of the centers of the hand and feet) of the hands and feet are covered with dark hairs, but the ungual tufts at the bases of the claws consist of longer, gray hairs. The fifth digit of the foot is long, with the tip of its claw almost reaching the base of the claw of the fourth digit. The tail is dark and hardly furred, except for a pencil of long hairs at the end; some animals have a white tail tip. Females have six mammae. In thirty-six specimens, head and body length is 94 to 119 mm (3.7 to 4.7 in), averaging 110 mm (4.3 in); tail length is 122 to 151 mm (4.8 to 5.9 in), averaging 140 mm (5.5 in); hindfoot length is 26 to 30 mm (1 to 1.2 in), averaging 28 mm (1.1 in); ear length is 17 to 20 mm (0.7 to 0.8 in), averaging 18 mm (0.7 in); and weight is 24 to 46 g (0.8 to 1.6 oz), averaging 36 g (1.3 oz).
The front (rostral) part of the skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
is short—shorter and broader than in T. hylophilus—and flat and the notches in the zygomatic plate
Zygomatic plate
In rodent anatomy, the zygomatic plate is a bony plate derived from the flattened front part of the zygomatic arch . At the back, it connects to the front 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...
s at the sides are poorly developed. The plates themselves are broad. The zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...
es (cheekbones) spread broadly and are rounded in shape. The narrow interorbital region
Interorbital region
The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups....
(between the eyes) is hourglass-shaped. The braincase is robust.
The incisive foramina
Incisive foramen
The fossa incisiva is an opening in the bone of the oral hard palate where blood vessels and nerves may pass. There are four of these openings in the incisive fossa.-Formation:...
, which perforate the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
between the incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s and the molars
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
, are short and do not reach near the first molars; they are longer in T. hylophilus. They are widest where the premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
ry and maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
ry bones meet. The palate itself is also short, not extending beyond the third molars, and is broad and lacks ridges or grooves. There are simple posterolateral palatal pits
Posterolateral palatal pits
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...
at the back of the palate, near the third molars. The mesopterygoid fossa, an opening located behind the end of the palate, is broad and its roof is either fully ossified or perforated by small sphenopalatine vacuities
Sphenopalatine vacuities
In rodents, sphenopalatine vacuities are perforations of the roof of the mesopterygoid fossa, the open space behind the palate, in between the parapterygoid fossae. They may perforate the presphenoid or basisphenoid bone...
where the presphenoid
Sphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...
and basisphenoid bones meet. An alisphenoid strut
Alisphenoid strut
In some rodents, the alisphenoid strut is an extension of the alisphenoid bone that separates two foramina in the skull, the masticatory–buccinator foramen and the foramen ovale accessorius...
separates two foramina
Foramen
In anatomy, a foramen is any opening. Foramina inside the body of humans and other animals typically allow muscles, nerves, arteries, veins, or other structures to connect one part of the body with another.-Skull:...
(openings) at the base of the skull, the buccinator-masticatory foramen and the foramen ovale accessorius. The pattern of grooves and foramina on the head indicates that the circulation of the arteries in the head of T. ucucha follows the primitive pattern. The tegmen tympani, the roof of the tympanic cavity
Tympanic cavity
The tympanic cavity is a small cavity surrounding the bones of the middle ear.It is formed from the tubotympanic recess, an expansion of the first pharyngeal pouch....
, overlaps the suspensory process
Process (anatomy)
In anatomy, a process is a projection or outgrowth of tissue from a larger body. The vertebra has several kinds of processes,such as: transverse process, prezygapophysis, postzygapophysis.-Examples:Examples of processes include:...
of the squamosal bone. At the back of the mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
(lower jaw), there is a capsular process
Capsular process
In rodents, the capsular process or projection is a bony capsule that contains the root of the lower incisor. It is visible on the labial side of the mandible as a raising in the bone...
to receive the root of the lower incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
, which is absent in T. hylophilus.
The large upper incisors are orthodont, with their cutting edge at about a right angle to the upper molars, and heavily pigmented with orange. Those of T. hylophilus are narrower, less procumbent, and less pigmented. The orthodont upper incisors suffice to distinguish T. ucucha from all other members of the genus but T. australis and T. daphne, which have much shorter and narrower incisors. The left and right molar rows are parallel. The molars are more hypsodont
Hypsodont
Hypsodont dentition is characterized by high-crowned teeth and enamel which extends past the gum line. This provides extra material for wear and tear. Some examples of animals with hypsodont dentition are cows, horses and deer; all animals that feed on gritty, fibrous material. The opposite...
(high-crowned) than in other Thomasomys. The anterocone, the cusp at the front of the first upper molar, is divided into distinct cuspules at the lingual (inner) and labial (outer) sides by an anteromedian flexus. The accessory ridges on the upper molars, the anterolophs and mesolophs, are less well-developed than in T. hylophilus. The third upper molar is reduced relative to the second, much more so than in T. hylophilus. The lower molars are generally similar to the uppers, but the anteroconid (the equivalent of the anterocone on the first lower molar) is often undivided and the third molar is unreduced.
The glans penis
Glans penis
The glans penis is the sensitive bulbous structure at the distal end of the penis. The glans penis is anatomically homologous to the clitoral glans of the female...
is rounded, short, and small and is superficially divided into left and right halves by a trough at the top and a ridge at the bottom. Most of the glans is covered with spines, except for an area near the tip.
Distribution and ecology
Thomasomys ucucha occurs only in the Cordillera Oriental of Ecuador in the provinces of Pichincha and Napo. At Papallacta, Thomasomys ucucha was collected in a variety of habitats at 3380 to 3720 m (11,090 to 12,200 ft) altitude, including páramoPáramo
The term páramo can refer to a variety of ecosystems. Some ecologists describe the páramo broadly as “all high, tropical, montane vegetation above the continuous timberline”. A more narrow term classifies the páramo according to its regional placement - specifically located in “the northern Andes...
(high-mountain grassland with shrubs and forest patches) and subalpine rainforest. Most were taken in runways (paths through vegetation made by animals) and a few alongside small streams or on a low tree. Other muroid rodents found at the same places as T. ucucha include two akodontines
Akodontini
Akodontini is the second most speciose 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 and Venezuela . It also includes genera previously placed in...
(grass mice), Akodon latebricola and Akodon mollis; two ichthyomyines
Ichthyomyini
Ichthyomyini is a tribe of New World rats and mice in the subfamily Sigmodontinae. The species within this tribe share the characteristic of all being fish-eating rodents.*Anotomys - Ecuadorian Fish-eating Rat*Chibchanomys - Chibchan Water Mouse...
(water rats), Anotomys leander and Neusticomys monticolus; two oryzomyines
Oryzomyini
Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of 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...
(rice rats), Microryzomys altissimus and M. minutus; the thomasomyine Chilomys instans; and five other species of Thomasomys, T. aureus, T. baeops, T. cinnameus, T. erro, and T. paramorum. Other species have been recorded nearby, and Voss wrote that T. ucucha may occur sympatrically with seven other species of Thomasomys. With Akodon latebricola and Thomasomys erro, T. ucucha is one of three species that are known only from the northeastern Andes of Ecuador.
Conservation status
Thomasomys ucucha is locally common, but has a very limited known distribution. Its conservation status has been assessed as "VulnerableVulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
" by the IUCN because of its small distribution; it may be threatened by the destruction of its habitat for agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
purposes, but occurs near two protected area
Protected area
Protected areas are locations which receive protection because of their recognised natural, ecological and/or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the enabling laws of each country or the regulations of the international...
s.
Literature cited
- Beolen, B., Watkins, M. and Grayson, M. 2009. The Eponym Dictionary of Mammals. Baltimore: The Johns Hopkins University Press, 591 pp. ISBN 978-0-8018-9304-9
- Musser, G.G.Guy MusserGuy Graham Musser is an American zoologist. His main research field is the subfamily Murinae, in which he has described many new species.Musser was born in Salt Lake City, Utah...
and Carleton, M.D. 2005. Superfamily Muroidea. Pp. 894–1531 in Wilson, D.E. and Reeder, D.M. (eds.). Mammal Species of the World: a taxonomic and geographic reference. 3rd ed. Baltimore: The Johns Hopkins University Press, 2 vols., 2142 pp. ISBN 978-0-8018-8221-0 - Pacheco, V., Tirira, D. and Boada, C. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on July 9, 2010.
- Tirira, D. 2007. Guia de campo de los mamíferos del Ecuador. Quito: Ediciones Murciélago Blanco, publicación especial sobre los mamíferos del Ecuador 6, 576 pp. (in Spanish). ISBN 9978-44-651-6
- Voss, R.S. 2003. A new species of Thomasomys (Rodentia: Muridae) from eastern Ecuador, with remarks on mammalian diversity and biogeography in the Cordillera Oriental. American Museum Novitates 3421:1–47.