Posterolateral palatal pits
Encyclopedia
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
(voles, lemmings, and relatives) and Oryzomyini
(rice rats and relatives) 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
.
have posterolateral palatal pits.
In Oryzomyini
(rice rats), the largest tribe of the Sigmodontinae, all but some species—Mindomys hammondi and Sigmodontomys aphrastus usually have only one small pit on each side of the palate—have prominent posterolateral palatal pits, often more than one on each side of the palate. In many oryzomyines, the pits are located in a deep depression or fossa
. This depression has been termed the "palatal fossa" in the genus Cerradomys
; its varying depth serves as a diagnostic character separating some of the species. The presence of complex posterolateral palatal pits is a synapomorphy
either of Oryzomyini or of Oryzomyini minus Mindomys. Members of the genus Nephelomys
usually have complex posterolateral palatal pits, recessed into deep fossae, but N. caracolus and N. nimbosus
have simpler pits. One of the putative subdivisions within Oryzomyini, Clade D, has posterolateral palatal pits recessed into a fossa as one of its synapomorphies, although the feature is reversed in several subgroups. The extinct island endemic Noronhomys vespuccii also had smaller pits, perhaps because of its short palate.
Among members of the tribe Thomasomyini, posterolateral palatal pits are small or absent. Aepeomys lacks them, but Rhagomys longilingua does have posterolateral palatal pits. The possible thomasomyine Abrawayaomys chebezi has small posterolateral palatal pits.
Members of the Phyllotini tribe always have posterolateral palatal pits. In some species, they are displaced to the back from their usual position just before the mesopterygoid fossa into the fossa. The condition of the pits has been used to separate species of Phyllotis
.
The tribe Ichthyomyini
is characterized by inconspicuous posterolateral palatal pits.
, a group that includes the vole
s and lemming
s, usually have posterolateral palatal pits, but the configuration of the pits is variable. In some species, the pits do not extend to the ventral face of the palate.
, including Peromyscus
(deer mice) and related genera.
analyses of oryzomyines by Weksler (2006), Carleton and Olson (1999), and Carleton and Musser (1989); neotomines by Carleton (1980); and phyllotines by Steppan (1995).
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
, posterolateral palatal pits are gaps at the sides of the back of the bony 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...
, near the last 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"....
. Posterolateral palatal pits are present, in various degrees of development, in several members of the 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....
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...
. Many members of the family lack them or have only simple pits, but Arvicolinae
Arvicolinae
The Arvicolinae are a subfamily of rodents that includes the voles, lemmings, and muskrats. They are most closely related to the other subfamilies in the Cricetidae . Some authorities place the subfamily Arvicolinae in the family Muridae along with all other members of the superfamily Muroidea...
(voles, lemmings, and relatives) and 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...
(rice rats and relatives) have more highly developed posterolateral palatal pits. Posterolateral palatal pits are also present in some other rodents, including Glis
Glis
Glis is an Electronic / Industrial music project founded in 2001 by Shaun Frandsen of Seattle, WA . The band has experienced several lineup changes and guest appearances, with frontman Shaun Frandsen acting as the primary producer, vocalist, songwriter, and instrumentalist...
, Jaculus
Jaculus
The jaculus is a small mythical serpent or dragon. It can be shown with wings and sometimes has front legs. It is also sometimes known as the javelin snake.-In Mythology:...
, Hystrix
Hystrix
Hystrix is a genus of porcupine that contains what are the best known and most distinctive of the Old World porcupines.-Species:*Genus Hystrix**Subgenus Thecurus***Hystrix crassispinis - Thick-spined Porcupine...
, Abrocoma
Abrocoma
Abrocoma is a genus of abrocomid rodents found in the Andes of South America, from southern Peru to central Chile. The genus contains eight species, most of which are found in isolated mountain ranges in northwestern Argentina.- Species :...
, Ctenomys, Chinchilla
Chinchilla
Chinchillas are crepuscular rodents, slightly larger and more robust than ground squirrels, and are native to the Andes mountains in South America. Along with their relatives, viscachas, they make up the family Chinchillidae....
, and Lagidium
Lagidium
Lagidium is a genus of rodent in the family Chinchillidae.It contains the following species:* Northern Viscacha * Southern Viscacha * Wolffsohn's Viscacha...
.
Sigmodontinae
Many members of the mainly South American cricetid subfamily SigmodontinaeSigmodontinae
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...
have posterolateral palatal pits.
In 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...
(rice rats), the largest tribe of the Sigmodontinae, all but some species—Mindomys hammondi and Sigmodontomys aphrastus usually have only one small pit on each side of the palate—have prominent posterolateral palatal pits, often more than one on each side of the palate. In many oryzomyines, the pits are located in a deep depression or fossa
Fossa (anatomy)
In anatomical terminology, fossa has come to mean a depression or hollow, in general, in a bone. Other parts of the body may be involved, for example, the antecubital fossa...
. This depression has been termed the "palatal fossa" in the genus Cerradomys
Cerradomys
Cerradomys is a genus of oryzomyine rodents from eastern Bolivia, Paraguay, and central Brazil found in cerrado, Caatinga and Gran Chaco habitats. The species in this genus have historically been placed in Oryzomys, but according to cladistic research, they are not more closely related to the type...
; its varying depth serves as a diagnostic character separating some of the species. The presence of complex posterolateral palatal pits is a synapomorphy
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
either of Oryzomyini or of Oryzomyini minus Mindomys. Members of the genus Nephelomys
Nephelomys
Nephelomys is a genus of South American oryzomyine rodents found in the Andes from Bolivia to Venezuela, with a westward extension into the mountains of Costa Rica...
usually have complex posterolateral palatal pits, recessed into deep fossae, but N. caracolus and N. nimbosus
Nephelomys nimbosus
Nephelomys nimbosus is a species of rodent in the genus Nephelomys of family Cricetidae. Its type locality is at San Antonio on the northeastern slope of the Tungurahua in the Andes of Ecuador, at an altitude of about . The type series included five individuals.The fur of the upperparts is brown to...
have simpler pits. One of the putative subdivisions within Oryzomyini, Clade D, has posterolateral palatal pits recessed into a fossa as one of its synapomorphies, although the feature is reversed in several subgroups. The extinct island endemic Noronhomys vespuccii also had smaller pits, perhaps because of its short palate.
Among members of the tribe Thomasomyini, posterolateral palatal pits are small or absent. Aepeomys lacks them, but Rhagomys longilingua does have posterolateral palatal pits. The possible thomasomyine Abrawayaomys chebezi has small posterolateral palatal pits.
Members of the Phyllotini tribe always have posterolateral palatal pits. In some species, they are displaced to the back from their usual position just before the mesopterygoid fossa into the fossa. The condition of the pits has been used to separate species of Phyllotis
Phyllotis
Phyllotis is a genus of rodent in the family Cricetidae.It contains the following species:* Phyllotis alisosiensis* Friendly Leaf-eared Mouse * Andean Leaf-eared Mouse...
.
The tribe Ichthyomyini
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...
is characterized by inconspicuous posterolateral palatal pits.
Arvicolinae
ArvicolinaeArvicolinae
The Arvicolinae are a subfamily of rodents that includes the voles, lemmings, and muskrats. They are most closely related to the other subfamilies in the Cricetidae . Some authorities place the subfamily Arvicolinae in the family Muridae along with all other members of the superfamily Muroidea...
, a group that includes the vole
Vole
A vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...
s and lemming
Lemming
Lemmings are small rodents, usually found in or near the Arctic, in tundra biomes. They are subniveal animals, and together with voles and muskrats, they make up the subfamily Arvicolinae , which forms part of the largest mammal radiation by far, the superfamily Muroidea, which also includes rats,...
s, usually have posterolateral palatal pits, but the configuration of the pits is variable. In some species, the pits do not extend to the ventral face of the palate.
Neotominae
Posterolateral palatal pits are poorly developed or absent in many members of the mostly North American subfamily NeotominaeNeotominae
Neotominae is a subfamily of the family Cricetidae. It consists of four tribes, 16 genera, and many species of New World rats and mice, predominantly found in North America. Among them are the well-known deer mice, white-footed mice, packrats, and grasshopper mice.Neotomines are related to the...
, including Peromyscus
Peromyscus
The genus Peromyscus contains the animal species commonly referred to as deer mice. This is a genus of New World mouse only distantly related to the common house mouse and laboratory mouse, Mus musculus...
(deer mice) and related genera.
Cladistics
The presence and development of posterolateral palatal pits has been used as a character in cladisticCladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
analyses of oryzomyines by Weksler (2006), Carleton and Olson (1999), and Carleton and Musser (1989); neotomines by Carleton (1980); and phyllotines by Steppan (1995).
Literature cited
- Carleton, M.D. 1980. Phylogenetic relationships in neotomine-peromyscine rodents (Muroidea) and a reappraisal of the dichotomy within New World Cricetinae. Miscellaneous Publications, Museum of Zoology, University of Michigan 157:i–vii+1–146.
- Carleton, M.D. 1989. Systematics and evolution. Pp. 7–141 in Kirkland, G.L. and Layne, J.N. (eds.). Advances in the study of Peromyscus (Rodentia). Lubbock: Texas Tech University Press.
- 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.
- Carleton, M.D. and Musser, G.G. 1989. Systematic studies of oryzomyine rodents (Muridae, Sigmodontinae): a synopsis of Microryzomys. Bulletin of the American Museum of Natural History 191:1–83.
- Carleton, M.D. and Olson, S.L. 1999. Amerigo Vespucci and the rat of Fernando de Noronha: a new genus and species of Rodentia (Muridae, Sigmodontinae) from a volcanic island off Brazil's continental shelf. American Museum Novitates 3256:1–59.
- Goldman, E.A. 1918. The rice rats of North America. North American Fauna 43:1–100.
- Hershkovitz, P. 1962. Evolution of Neotropical cricetine rodents (Muridae) with special reference to the phyllotine group. Fieldiana Zoology 46:1–524
- Hooper, E.T. and Hart, B.S. 1962. A synopsis of recent North American microtine rodents. Miscellaneous Publications, Museum of Zoology, University of Michigan 120:1–68.
- Jenkins, P.D., Kilpatrick, C.W., Robinson, M.F. and Timmins, R.J. 2005. Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR. Systematics and Biodiversity 2(4):419–454.
- Luna, L. and Patterson, B.D. 2003. A remarkable new mouse (Muridae: Sigmodontinae) from southeastern Peru: with comments on the affinities of Rhagomys rufescens (Thomas, 1886). Fieldiana Zoology 101:1–24.
- Pardiñas, U.F.J., Teta, P. and D'Elía, G. 2009. Taxonomy and distribution of Abrawayaomys (Rodentia: Cricetidae), an Atlantic Forest endemic with the description of a new species. Zootaxa 2128:39–60.
- Percequillo, A.R., E. Hingst-Zaher, and C.R. Bonvicino. 2008. Systematic review of genus Cerradomys Weksler, Percequillo and Voss, 2006 (Rodentia: Cricetidae: Sigmodontinae: Oryzomyini), with description of two new species from Eastern Brazil. American Museum Novitates 3622: 1–46.
- Steppan, S.J. 1995. Revision of the tribe Phyllotini (Rodentia: Sigmodontinae), with a phylogenetic hypothesis for the Sigmodontinae. Fieldiana Zoology 80:1–112.
- Voss, R.S. 1988. Systematics and ecology of ichthyomyine rodents (Muroidea): patterns of morphological evolution in a small adaptive radiation. Bulletin of the American Museum of Natural History 188:259–493.
- Voss, R.S. and Carleton, M.D. 1993. A new genus for Hesperomys molitor Winge and Holochilus magnus Hershkovitz (Mammalia, Muridae) with an analysis of its phylogenetic relationships. American Museum Novitates 3085:1–39.
- Voss, R.S., Lunde, D.P. and Simmons, N.B. 2001. The mammals of Paracou, French Guiana: a Neotropical lowland rainforest fauna. Part 2. Nonvolant species. Bulletin of the American Museum of Natural History 263:1–236.
- Voss, R.S., Gómez-Laverde, M. and Pacheco, V. 2002. A new genus for Aepeomys fuscatus Allen, 1912, and Oryzomys intectus Thomas, 1921: Enigmatic muroid rodents from Andean cloud forests. American Museum Novitates 3373:1–42.
- 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.