Oryzomys peninsulae | |
---|---|
Skull of Oryzomys peninsulae, seen from above [1] | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Cricetidae |
Subfamily: | Sigmodontinae |
Genus: | Oryzomys |
Species: | O. peninsulae |
Binomial name | |
Oryzomys peninsulae Thomas, 1897 | |
Distribution of Oryzomys peninsulae (in dark green) and other western Mexican Oryzomys | |
Synonyms [3] | |
Oryzomys peninsulae, also known as the Lower California rice rat, [4] is a species of rodent from western Mexico. Restricted to the southern tip of the Baja California peninsula, it is a member of the genus Oryzomys of family Cricetidae. Only about twenty individuals, collected around 1900, are known, and subsequent destruction of its riverine habitat may have driven the species to extinction.
Medium in size for its genus, it was first described as a separate species, but later lumped into other, widespread species until it was reinstated as separate in 2009. It is distinctive in fur color—grayish brown on the forequarters and reddish brown on the hindquarters—and in some dimensions of its skull, with a high braincase, robust zygomatic arches (cheekbones), and long incisive foramina (perforations of the palate between the incisors and the molars).
Oryzomys peninsulae was first collected in 1896 and Oldfield Thomas described it in 1897 as a full species of Oryzomys . [5] It was retained as a distinct species related to O. couesi and O. palustris until 1971, when Philip Hershkovitz swept it, and other outlying populations of the same species group, as subspecies under an expanded concept of O. palustris. [6] Raymond Hall concurred in the second edition (1981) of Mammals of North America, arguing that O. peninsulae differed less from mainland Oryzomys populations (currently classified as O. couesi mexicanus) than some other forms he included in O. palustris differed from each other. [7] After studies of the contact zone between North American O. palustris and Central American O. couesi in southern Texas and northeastern Tamaulipas (by Benson and Gehlbach in 1979 and Schmidt and Engstrom in 1994) made clear that the two are distinct from each other, O. peninsulae remained as a subspecies of O. couesi. [6] In 2009, Michael Carleton and Joaquín Arroyo-Cabrales reviewed the classification of western Mexican Oryzomys and used morphological and morphometrical data to characterize four distinct Oryzomys species in the region. O. peninsulae and another isolated population, O. nelsoni from the Islas Marías, were both retained as separate species, as was O. albiventer from montane mainland Mexico. They kept the population in the coastal lowlands as a subspecies, O. couesi mexicanus, of Oryzomys couesi. [8]
The genus Oryzomys currently includes about eight species distributed from the eastern United States (O. palustris) into northwestern South America ( O. gorgasi ). [9] O. peninsulae is part of the O. couesi section, which is centered on the widespread Central American O. couesi and also includes various other species with more limited and peripheral distributions. [10] Many aspects of the systematics of this section remain unclear and it is likely that the current classification underestimates the group's true diversity. [11] Oryzomys was previously a much larger genus, but most species were progressively removed in various studies, culminating in contributions by Marcelo Weksler and coworkers in 2006 that excluded more than forty species from the genus. [12] Oryzomys and many of the species removed from it are classified in the tribe Oryzomyini ("rice rats"), a diverse assemblage of American rodents of over a hundred species, [13] and on higher taxonomic levels in the subfamily Sigmodontinae of family Cricetidae, along with hundreds of other species of mainly small rodents. [14]
Oryzomys peninsulae is a medium-sized member of the genus, smaller than O. albiventer but larger than O. couesi mexicanus. Its fur is grayish-brown on the forequarters, but reddish-brown on the hindquarters; this coloration pattern is unique among western Mexican Oryzomys. [3] The underparts are a dirty white, the feet white above, and the tail dark or brownish above and dirty white below. [15]
In the skull, the braincase is high, the zygomatic arches (cheekbones) are broad and squared, and the incisive foramina, which perforate the palate between the incisors and the molars, are long and broad. The upper incisors are orthodont, with their cutting edge nearly vertical. [3] Morphometrically, the skull of O. peninsulae is sharply distinct from other western Mexican Oryzomys. [16]
In fourteen specimens measured by Carleton and Arroyo-Cabrales, total length was 227 to 305 mm (8.9 to 12.0 in), averaging 265.6 mm (10.46 in); head and body length was 113 to 152 mm (4.4 to 6.0 in), averaging 128.9 mm (5.07 in); tail length was 114 to 156 mm (4.5 to 6.1 in), averaging 136.8 mm (5.39 in); hindfoot length was 29 to 34 mm (1.1 to 1.3 in), averaging 32.0 mm (1.26 in); and occipitonasal length (a measure of total skull length) was 27.8 to 34.3 mm (1.09 to 1.35 in), averaging 31.5 mm (1.24 in). [17]
Twenty-one specimens of O. peninsulae are known: six were caught at Santa Anita in 1896 by D. Coolidge, and Edward William Nelson and Edward Alphonso Goldman obtained fifteen additional individuals in 1906 at San José del Cabo. [18] The two localities, which are about 13 km (8.1 mi) apart, were both located along the Río San José, a river in southernmost Baja California Sur, near the southern tip of the Baja California peninsula. Like other Oryzomys species, O. peninsulae is semiaquatic, spending much of its time in the water, but suitable habitat for such a species is estimated to be no more than 13 km2 (5.0 sq mi) on the arid Baja California peninsula. [19]
Río San José no longer exists, having fallen prey to irrigation projects, and touristic development of its estuary has resulted in pollution. Biologists working in the area in 1979 and from 1991 to 1993 failed to find O. peninsulae, casting doubt on its continued existence. The lack of records for over a century, small distribution, and destruction of the only known habitat led Carleton and Arroyo-Cabrales to consider the conservation status of O. peninsulae as "critically endangered, if not extinct". They noted that the status of the species had previously been obscured because it had been lumped for decades with O. couesi, a widely distributed and secure species. [2]
It is uncertain how Oryzomys peninsulae arrived at its recent locale in Baja California Sur. In 1922, Nelson suggested that it may have been introduced from another part of Mexico in a shipment of farm products, but this hypothesis is disproved by the clear differentiation from other western Mexican Oryzomys that the species exhibits. [11]
The species's range may be relictual in nature: [11] while Oryzomys is currently found along the eastern coast of the Gulf of California only as far north as coastal southern Sonora, [20] the past distribution of the genus may have extended further northward, perhaps even into the southwestern United States, and from there south into Baja California. Subsequent disappearance of Oryzomys from the northern regions would have led to its observed disjunct distribution, with O. peninsulae isolated on the peninsula. This possibility is supported by the relatively close resemblance between O. peninsulae and O. couesi mexicanus, from coastal western Mexico. [21]
Alternatively, the ancestor of Oryzomys peninsulae may have arrived by rafting during the late Miocene, about six million years ago, when the southern tip of the Baja California peninsula was an island located near what is now Nayarit and Jalisco in western Mexico. Some plants and birds from the area may have a similar biogeographic heritage. [22]
Oryzomys nelsoni is an extinct rodent of María Madre Island, Nayarit, Mexico. Within the genus Oryzomys of the family Cricetidae, it may have been most closely related to the mainland species O. albiventer. Since its first description in 1898, most authors have regarded it as a distinct species, but it has also been classified as a mere subspecies of the marsh rice rat (O. palustris).
Oryzomys couesi, also known as Coues's rice rat, is a semiaquatic rodent in the family Cricetidae occurring from southernmost Texas through Mexico and Central America into northwestern Colombia. It is usually found in wet habitats, such as marshes, but also lives in drier forests and shrublands. Weighing about 43 to 82 g, O. couesi is a medium-sized to large rat. The coarse fur is buff to reddish above and white to buff below. The hindfeet show some specializations for life in the water, such as reduced ungual tufts of hair around the digits. It has 56 chromosomes. There is much geographic variation in size, proportions, color, and skull features. Oryzomys couesi is active during the night and builds nests of vegetation that are suspended among reeds about 1 m (3.3 ft) above the ground. It is an excellent swimmer and dives well, but can also climb in vegetation. An omnivore, it eats both plant and animal food, including seeds and insects. It breeds throughout the year; females give birth to about four young after a pregnancy of 21 to 28 days. The species may be infected by several different parasites and by two hantaviruses.
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 (O. palustris) of the United States and O. couesi of Mexico and Central America—are widespread; the six others have more restricted distributions. The species have had eventful taxonomic histories, and most species were at one time included in the marsh rice rat; additional species may be recognized in the future. The name Oryzomys was established in 1857 by Spencer Fullerton Baird for the marsh rice rat and was soon applied to over a hundred species of American rodents. Subsequently, the genus gradually became more narrowly defined until its current contents were established in 2006, when ten new genera were established for species previously placed in Oryzomys.
Euryoryzomys emmonsae, also known as Emmons' rice rat or Emmons' oryzomys, is a rodent from the Amazon rainforest of Brazil in the genus Euryoryzomys of the family Cricetidae. Initially misidentified as E. macconnelli or E. nitidus, it was formally described in 1998. A rainforest species, it may be scansorial, climbing but also spending time on the ground. It lives only in a limited area south of the Amazon River in the state of Pará, a distribution that is apparently unique among the muroid rodents of the region.
Oligoryzomys is a genus of rodents in the tribe Oryzomyini of family Cricetidae. Many species are known as pygmy rice rats or colilargos. The genus is found from Mexico to Tierra del Fuego and includes approximately 17 species.
Nephelomys albigularis, also known as the white-throated oryzomys or Tomes's rice rat, is a species of rodent in the genus Nephelomys of family Cricetidae. Described in 1860, it was the first Nephelomys species to be discovered. It was originally described in the defunct genus Hesperomys as Hesperomys albigularis and considered related to the much smaller H. longicaudatus. By 1894, it was placed in Oryzomys, as Oryzomys albigularis, and associated with what is now Nephelomys meridensis. In the early 1960s, the scope of the species was considerably expanded to include most of the species that are now in Nephelomys, as well as a single name, boliviae, that is currently a synonym of Euryoryzomys nitidus. From 1976 on, several of these were reinstated as separate species.
Handleyomys alfaroi, also known as Alfaro's rice rat or Alfaro's oryzomys, is a species of rodent in the genus Handleyomys of family Cricetidae. It is found in Belize, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, and Panama. It was previously included in Oryzomys as Oryzomys alfaroi. Its natural habitats are subtropical and tropical lowland or montane dry forests at elevations ranging from sea level to 2500 m.
Handleyomys chapmani, also known as Chapman's oryzomys or Chapman's rice rat, is a species of rodent in the genus Handleyomys of family Cricetidae. It is found only in Mexico. It was previously placed in Oryzomys as Oryzomys chapmani, but has been provisionally transferred to the genus Handleyomys pending the description of a new genus to contain it.
Oryzomys dimidiatus, also known as the Nicaraguan oryzomys, Thomas's rice rat, or the Nicaraguan rice rat, is a rodent in the family Cricetidae. It is known from only three specimens, all collected in southeastern Nicaragua since 1904. Placed in Nectomys upon its discovery, it was later classified in its own subgenus of Oryzomys and finally recognized as closely related to other species now placed in Oryzomys, including the marsh rice rat and Coues' rice rat, which occurs in the same region.
Oryzomys gorgasi, also known as Gorgas's oryzomys or Gorgas's rice rat, is a rodent in the genus Oryzomys of family Cricetidae. First recorded in 1967, it is known from only a few localities, including a freshwater swamp in the lowlands of northwestern Colombia and a mangrove islet in northwestern Venezuela. It reportedly formerly occurred on the island of Curaçao off northwestern Venezuela; this extinct population has been described as a separate species, Oryzomys curasoae, but does not differ morphologically from mainland populations.
The marsh rice rat is a semiaquatic North American rodent in the family Cricetidae. It usually occurs in wetland habitats, such as swamps and salt marshes. 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 have been a commensal in corn-cultivating communities. Weighing about 40 to 80 g, the marsh rice rat is a medium-sized rodent that resembles the common black and brown rat. The upperparts are generally gray-brown, but are reddish in many Florida populations. The feet show several specializations for life in the water. The skull is large and flattened, and is short at the front.
Eremoryzomys polius, also known as the gray rice rat or the Marañon oryzomys, is a rodent species in the tribe Oryzomyini of the family Cricetidae. Discovered in 1912 and first described in 1913 by Wilfred Osgood, it was originally placed in Oryzomys and named Oryzomys polius. In 2006, a cladistic analysis found that it was not closely related to Oryzomys in the strict sense or to any other oryzomyine then known, so that it is now placed in its own genus, Eremoryzomys. The Brazilian genus Drymoreomys, named in 2011, is probably the closest relative of Eremoryzomys. Eremoryzomys has a limited distribution in the dry upper valley of the Marañón River in central Peru, but may yet contain more than one species.
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.
Oryzomys antillarum, also known as the Jamaican rice rat, is an extinct rodent of Jamaica. A member of the genus Oryzomys within the family Cricetidae, it is similar to O. couesi of mainland Central America, from where it may have dispersed to its island during the last glacial period. O. antillarum is common in subfossil cave faunas and is also known from three specimens collected live in the 19th century. Some historical records of Jamaican rats may pertain to it. The species probably became extinct late in the 19th century, perhaps due to the introduction of the small Asian mongoose, competition with introduced rodents such as the brown rat, and habitat destruction.
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.
Oryzomys albiventer is a rodent in the genus Oryzomys of family Cricetidae from interior western Mexico, in the states of Jalisco, Guanajuato, and Michoacán. First described in 1901 as a separate species, it was later lumped under O. couesi and the marsh rice rat (O. palustris) until it was reinstated as a species in 2009. It differs from neighboring Oryzomys populations in size and measurements and is a large, brightly colored species with a long tail and robust skull and molars. Its range has been much impacted by agricultural development, but isolated populations are thought to persist.
Santa Anita is a village in Los Cabos Municipality, Baja California Sur, western Mexico. It is located north of San Jose del Cabo on the right bank of the Arroyo San José along Federal Highway 1. It had a population of 687 inhabitants in the 2010 census, and is situated at an elevation of 76 meters (249 ft.) above sea level.
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.
?Oryzomys pliocaenicus is a fossil rodent from the Hemphillian of Kansas, central United States. It is known from a single mandible with the back part missing. All three molars are present, but very worn. Together, the molars are 3.6 mm long. The fossil was discovered in 1935 and described in 1939 as a possible species of Oryzomys. Later authors doubted this allocation and suggested that it may instead belong in Bensonomys or Jacobsomys, but the material may not allow a definite identification.
In zoological nomenclature, an incorrect subsequent spelling is a name whose spelling has been unjustifiably and unintentionally changed from the original. It is distinct from a "mandatory change", a change to the original spelling that is required by the International Code of Zoological Nomenclature, and an "emendation", an intentional change to a name that may or may not be justified.