Gorgas's Rice Rat - AbsoluteAstronomy.com

Oryzomys gorgasi, also known as Gorgas's Oryzomys or Gorgas's Rice Rat, is a rodent

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 Oryzomys
Oryzomys
Oryzomys is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat of the United States and O. couesi of Mexico and Central America—are widespread; the six others have...

of 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...

. First collected as a living animal in 1967, it is known from only a few localities, including a freshwater swamp in the lowlands of northwestern Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

and a mangrove islet in northwestern Venezuela

Venezuela

Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...

. It formerly occurred on the island of Curaçao

Curaçao

Curaçao is an island in the southern Caribbean Sea, off the Venezuelan coast. The Country of Curaçao , which includes the main island plus the small, uninhabited island of Klein Curaçao , is a constituent country of the Kingdom of the Netherlands...

off northwestern Venezuela; this extinct population has been described as a separate species, Oryzomys curasoae, but does not differ morphologically from mainland populations.

Oryzomys gorgasi is a medium-sized, brownish species with large, semiaquatically specialized feet. It differs from other Oryzomys species in several features of its skull. Its diet includes crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, and plant material, and parasitic nematode

Nematode

The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...

s infect it. The species is listed as "Endangered" by the International Union for Conservation of Nature due to destruction of its habitat and competition with the introduced black rat

Black Rat

The black rat is a common long-tailed rodent of the genus Rattus in the subfamily Murinae . The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and spreading with Europeans across the world.-Taxonomy:The black rat was...

(Rattus rattus).

Taxonomy

Oryzomys gorgasi was first found in Antioquia Department

Antioquia Department

Antioquia is one of the 32 departments of Colombia, located in the central northwestern part of Colombia with a narrow section that borders the Caribbean Sea. Most of its territory is mountainous with some valleys, much of which is part of the Andes mountain range...

of northwestern Colombia in 1967 during an expedition by the U.S. Army Medical Department and the Gorgas Memorial Laboratory. In 1971, Field Museum

Field Museum of Natural History

The Field Museum of Natural History is located in Chicago, Illinois, USA. It sits on Lake Shore Drive next to Lake Michigan, part of a scenic complex known as the Museum Campus Chicago...

zoologist Philip Hershkovitz

Philip Hershkovitz

Philip Hershkovitz was an American mammalogist. Born in Pittsburgh, he attended the Universities of Pittsburgh and Michigan and lived in South America collecting mammals. In 1947, he was appointed a curator at the Field Museum of Natural History in Chicago and he continued to work there until his...

described a new species, Oryzomys gorgasi, on the basis of the single known specimen, an old male. He named the animal after physician William Crawford Gorgas, the namesake of the Gorgas Memorial Laboratory. Hershkovitz considered the new species most closely related to Oryzomys palustris, which at the time included North and Central American populations now divided into several species, including the marsh rice rat

Marsh Rice Rat

The marsh rice rat is a semiaquatic North American rodent in the family Cricetidae. It is found mostly in the eastern and southern United States, from New Jersey and Kansas south to Florida and northeasternmost Tamaulipas, Mexico; its range previously extended further west and north, where it may...

(O. palustris) and O. couesi. The species was not recorded again until 2001, when Venezuelan zoologist J. Sánchez H. and coworkers reported on 11 specimens collected in coastal northwestern Venezuela in 1992, 700 km (400 mi) from the Colombian locality. They confirmed that O. gorgasi is a distinct species related to the O. palustris group.

In 2001, Donald McFarlane and Adolphe Debrot described a new Oryzomys species from the Dutch

Kingdom of the Netherlands

The Kingdom of the Netherlands is a sovereign state and constitutional monarchy with territory in Western Europe and in the Caribbean. The four parts of the Kingdom—Aruba, Curaçao, the Netherlands, and Sint Maarten—are referred to as "countries", and participate on a basis of equality...

island of Curaçao

Curaçao

off northwestern Venezuela. For their description, they used subfossil

Subfossil

Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....

material from owl pellets

Pellet (ornithology)

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 matter, bones, fur, feathers, bills, claws, and teeth...

, including two partial 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...

s and several hemimandible

Mandible

The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...

s. They referred the species to Oecomys
Oecomys
Oecomys is a genus of rodent within the tribe Oryzomyini of family Cricetidae. It contains about 17 species, which live in trees and are distributed across forested parts of South America, extending into Panama and Trinidad.-Literature cited:...

, a group of arboreal (tree-living), mainly South American rodents related to Oryzomys. O. curasoae has also been known as the "Curaçao Rice Rat" and the "Curaçao Oryzomys".

Marcelo Weksler and colleagues removed most of the species then placed in Oryzomys from the genus in 2006, retaining only the marsh rice rat and related species, including O. gorgasi. They also kept O. curasoae in the genus and suggested that it may not be distinct from O. gorgasi. In a 2009 paper, R.S. Voss and Weksler examined the two and concluded that they represented the same species on the basis of direct comparisons and a phylogenetic analysis. The resultant tree

Phylogenetic tree

A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...

placed O. curasoae and O. gorgasi sister to each other and closer to O. couesi than to the marsh rice rat. Accordingly, they placed O. curasoae as a junior synonym of the earlier described O. gorgasi.

Oryzomys gorgasi is the southeasternmost representative of the genus Oryzomys, which extends north into the eastern United States (marsh rice rat, O. palustris). O. gorgasi is further part of the O. couesi section, which is centered around the widespread Central American O. couesi and also includes six other species with more limited and peripheral distributions. Many aspects of the systematics

Systematics

Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...

of the O. couesi section remain unclear and it is likely that the current classification underestimates the true diversity of the group. Oryzomys is classified in the tribe Oryzomyini

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...

, a diverse assemblage of American rodents of over a hundred species, and on higher taxonomic levels in 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 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

Oryzomys gorgasi is a medium-sized oryzomyine

Oryzomyini

with small ears and large feet, and is similar to the marsh rice rat in general appearance. The long and coarse fur is brownish above and ochraceous below. At the base of the tail, the upper and lower sides differ in color and at the end is a short tuft of hairs. The scales on the tail are well-developed. As in other Oryzomys, the hindfeet exhibit specializations for life in the water. The plantar (lower) surface of the metatarsus

Metatarsus

The metatarsus or metatarsal bones are a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth...

is naked. Two of the pads are very small. Ungual tuft

Ungual tuft

In mammals, ungual tufts are tufts of hairs at the base of claws of the fore- and hindfeet. Their presence has been used as a character in cladistic studies of Cricetidae....

s, tufts of hair at the bases of the claws, are poorly developed. Interdigital webbing

Interdigital webbing

Interdigital webbing is the presence of membranes of skin between the digits. Normally in mammals, webbing is present in the embryo but resorbed later in development, but in various mammal species it occasionally persists in adulthood...

is present, but extends along less than half of the first phalanges.

In specimens from El Caimito, total length is 220 to 290 mm (8.7 to 11 in), averaging 259 mm (10.2 in) (measured in 6 specimens); tail length is 116 to 138 mm (4.6 to 5.4 in), averaging 130 mm (5.1 in) (measured in 8 specimens); hindfoot length is 30 to 32 mm (1.18 to 1.26 in), averaging 31 mm (1.22 in) (measured in 10 specimens); ear length is 15 to 17 mm (0.59 to 0.67 in), averaging 16 mm (0.63 in) (measured in 7 specimens); and condylo-incisive length (a measure of total skull size) is 26.9 to 31.4 mm (1.06 to 1.24 in), averaging 29.6 mm (1.17 in) (measured in 5 specimens). In the holotype

Holotype

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

from Colombia, an old male, total length is 240 mm (9.4 in); tail length is 125 mm (4.9 in); ear length is 19 mm (0.75 in); and condylo-incisive length is 32.1 mm (1.26 in). The collector recorded the holotype's hindfoot as being 34 mm (1.34 in) long, but Sánchez and colleagues remeasured it as 33 mm (1.30 in).

The rostrum (front part of the skull

Skull

) is short. The broad 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...

develops a prominent notch, but not a spine, on its front end, and its back margin is in front of the first molars. The 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....

, located between the eyes, is narrowest towards the front and is flanked by beadings along its margins. The interparietal bone is relatively long. 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:...

, perforations 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...

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 narrow and long and taper towards the end. The palate itself is also long, extending beyond the molars, and includes prominent 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...

near the third molars, which are excavated into deep fossae. The roof of the mesopterygoid fossa, the opening behind the palate, is not perforated by 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...

. O. gorgasi lacks 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...

; in some other oryzomyines, this extension of the alisphenoid bone separates two openings in the skull, the masticatory–buccinator foramen and the foramen ovale accessorius. The squamosal bone lacks a suspensory process that contacts 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....

, a defining character of oryzomyines. The subsquamosal fenestra

Subsquamosal fenestra

In some rodents, the subsquamosal fenestra is an opening between two parts of the squamosal bone, at the back of the skull. It can be seen in lateral view. Most Oryzomyini have the fenestra, but some species, including those in the genera Nectomys, Sigmodontomys, and Melanomys among others, lack...

, an opening at the back of the skull determined by the shape of the squamosal, is almost absent.

In the mandible

Mandible

The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...

(lower jaw), the upper and lower masseteric ridges come close together below the first molars, but do not fuse. The back end of the lower incisor root is in 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...

, a raising of the mandibular bone behind the molars. The upper incisors have yellowish enamel and are opisthodont, with the cutting edge inclined backwards. The molars are relatively small and are brachydont

Brachydont

Brachydont is a type of dentition characterized by low-crowned teeth, as opposed to high-crowned, hypsodont teeth. Human teeth are brachydont.-External links:*http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/tooth_diversity.html...

(low-crowned) and bunodont (with the cusps higher than the connecting crests). They are similar to those of the marsh rice rat in structural details. The upper and lower first molars have small accessory roots, as in many other oryzomyines, and the second and third lower molar each have two roots only.

Oryzomys gorgasi is distinguished from other Oryzomys species by its short rostrum, the form of its incisive foramina, the absence of sphenopalatine vacuities, and the near absence of a subsquamosal fenestra. Within the species, the Colombian specimen differs from the Venezuelan animals in being larger in some measurements, but having smaller teeth, and in having oddly shaped wear facets of the incisors. The Colombian animal was probably kept in captivity for some time after it was caught, which would explain its large size and odd wear facets. There are no substantial differences between mainland O. gorgasi and material from Curaçao.

Distribution and ecology

As far as known, Oryzomys gorgasi has a disjunct distribution in northwestern South America, including Colombia, Venezuela, and Curaçao. In a 2009 paper, Carleton and Arroyo-Cabrales speculated that its distribution may extend into Central America. The Colombian population is known from the holotype only, caught at Loma Teguerre (7°54'N, 77°W) in Antioquia Department, northwestern Colombia, near the Río Atrato, at about 1 m above sea level. The location is apparently a freshwater swamp, and Hershkovitz suggested that O. gorgasi probably occurred throughout the swamp forests in the Río Atrato basin. On Curaçao, it is known from cave faunas at Tafelberg Santa Barbara, Noordkant, Ser'i Kura, and Hermanus. At Tafelberg Santa Barbara, it was found in association with introduced

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

black rat

Black Rat

s (Rattus rattus), indicating that the population persisted at least until the first European contact in 1499.

In Venezuela, it was found on El Caimito, a small (57 ha, 140 acres) islet just east of the outlet of Lake Maracaibo

Lake Maracaibo

Lake Maracaibo is a large brackish bay in Venezuela at . It is connected to the Gulf of Venezuela by Tablazo Strait at the northern end, and fed by numerous rivers, the largest being the Catatumbo. It is commonly considered a lake rather than a bay or lagoon, and at 13,210 km² it would be the...

in the state of Zulia

Zulia

Zulia State is one of the 23 states of Venezuela. The state capital is Maracaibo. In June 30, 2010, it had an estimated population of 3,821,068, giving it the largest population among Venezuela's states. It is located in the northwestern part of the country...

, where the only other native non-flying mammal is the opossum Marmosa robinsoni. El Caimito is separated from the mainland by a narrow, brackish channel and contains sand banks with xerophytic vegetation surrounded by marshy lagoons with Rhizospora mangle mangrove

Mangrove

Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

s. Oryzomys gorgasi was caught in all habitats on the islet, but has not been found in other similar sites in northwestern Venezuela, where the introduced black rat is the only rodent collected. Analysis of stomach

Stomach

The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...

contents of El Caimito specimens indicates that the species is an omnivore

Omnivore

Omnivores are species that eat both plants and animals as their primary food source...

, with a diet including crustacean

Crustacean

s, insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, plant seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

s, and other plant material. The crustaceans may include fiddler crab

Fiddler crab

A fiddler crab, sometimes known as a calling crab, may be any of approximately 100 species of semi-terrestrial marine crabs which make up the genus Uca. As members of the family Ocypodidae, fiddler crabs are most closely related to the ghost crabs of the genus Ocypode. This entire group is composed...

s (Uca) and a mangrove tree crab of the genus Aratus
Aratus pisonii
Aratus pisonii, commonly known as the mangrove tree crab, is a species of crab which lives in mangrove trees in tropical and subtropical parts of the Americas, from Florida to Brazil on the Atlantic coast, and from Nicaragua to Peru on the Pacific coast. It feeds mostly on the leaves of the...

; the insects include flies

Fly

True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...

(Diptera); and the plants include grass

Grass

Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

seeds. Two parasitic

Parasitic worm

Parasitic worms or helminths are a division of eukaryoticparasites that, unlike external parasites such as lice and fleas, live inside their host. They are worm-like organisms that live and feed off living hosts, receiving nourishment and protection while disrupting their hosts' nutrient...

nematode

Nematode

s, Litomosoides sigmodontis (family Onchocercidae

Onchocercidae

Onchocercidae Chabaud & Anderson, 1959 is a family of nematodes in the superfamily Filarioidea. This family includes some of the most devastating human parasitic diseases, such as Lymphatic filariasis, Onchocerciasis, Loiasis, and other filariases....

) and an undetermined species of Pterygodermatites
Pterygodermatites
Pterygodermatites is a genus of parasitic nematodes in the family Rictulariidae. Species include:*Pterygodermatites jägerskiöldi*Pterygodermatites kozeki*Pterygodermatites ondatrae*Pterygodermatites peromysci...

(family Rictulariidae), are known to infect O. gorgasi. The 2009 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...

tersely indicates that the species has been found in second Venezuelan locality.

Conservation status

On the 2009 IUCN Red List, O. gorgasi is currently listed as "endangered" and O. curasoae as "data deficient". The species may be threatened by competition

Interspecific competition

Interspecific competition, in ecology, is a form of competition in which individuals of different species compete for the same resource in an ecosystem...

with introduced black rats and destruction of its habitat

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...

, but does occur in at least one 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...

. Displacement by the black rat has caused the species to become locally extinct in parts of its Venezuelan range. Suitable habitats for O. gorgasi exist in inland Venezuela, and further study is needed to determine whether it is present there. The extinction of the Curaçao population may also have been caused by competition with the black rat, which has been found together with Oryzomys in subfossil deposits.

Literature cited

Carleton, M.D. and Arroyo-Cabrales, J. 2009. Review of the Oryzomys couesi complex (Rodentia: Cricetidae: Sigmodontinae) in western Mexico. Bulletin of the American Museum of Natural History 331:94–127.
Hershkovitz, P. 1971. A new rice rat of the Oryzomys palustris group (Cricetinae, Muridae) from northwestern Colombia, with remarks on distribution (subscription required). Journal of Mammalogy 52(4):700–709.
Lamoreux, J. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on November 30, 2009.
McFarlane, D.A. and Debrot, A.O. 2001. A new species of extinct oryzomyine rodent from the Quaternary of Curaçao, Netherlands Antilles. Caribbean Journal of Science 37(3–4):182–184.
Musser, G.G. 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
Ochoa, J., Gómez-Laverde, M., Weksler, M. and Timm, R. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on November 30, 2009.
Sánchez H., J., Ochoa G., J. and Voss, R.S. 2001. Rediscovery of Oryzomys gorgasi (Rodentia: Muridae) with notes on taxonomy and natural history (subscription required). Mammalia 65:205–214.
Voss, R.S. and Weksler, M.W. 2009. On the taxonomic status of Oryzomys curasoae McFarlane and Debrot, 2001, (Rodentia: Cricetidae: Sigmodontinae) with remarks on the phylogenetic relationships of O. gorgasi Hershkovitz, 1971. Caribbean Journal of Science 45(1):73–79.
Weksler, M. 2006. Phylogenetic relationships of oryzomyine rodents (Muroidea: Sigmodontinae): separate and combined analyses of morphological and molecular data. Bulletin of the American Museum of Natural History 296:1–149.
Weksler, M., Percequillo, A.R. and Voss, R.S. 2006. Ten new genera of oryzomyine rodents (Cricetidae: Sigmodontinae). American Museum Novitates 3537:1–29.

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