Oryzomys és un gènere de rosegadors semiaquàtics de la tribu dels orizominis que viuen al sud de Nord-amèrica i l'extrem nord de Sud-amèrica. Inclou vuit espècies, de les quals dues (O. palustris als Estats Units i O. couesi a Mèxic i Centreamèrica) tenen una àmplia difusió, mentre que les altres sis tenen un àmbit de distribució més petit. La història taxonòmica de les espècies ha experimentat molts canvis, i antigament se n'agrupava la majoria dins O. palustris. És possible que se'n reconeguin noves espècies en el futur. El nom Oryzomys fou encunyat per Spencer Fullerton Baird el 1857 per O. palustris i aviat fou aplicat a més d'un centenar d'espècies de rosegadors americans. Posteriorment, el gènere anà sent redefinit amb criteris més estrictes fins que el seu contingut actual fou establert el 2006, quan es crearen deu nou gèneres per espècies antigament classificades dins d'Oryzomys.
Oryzomys és un gènere de rosegadors semiaquàtics de la tribu dels orizominis que viuen al sud de Nord-amèrica i l'extrem nord de Sud-amèrica. Inclou vuit espècies, de les quals dues (O. palustris als Estats Units i O. couesi a Mèxic i Centreamèrica) tenen una àmplia difusió, mentre que les altres sis tenen un àmbit de distribució més petit. La història taxonòmica de les espècies ha experimentat molts canvis, i antigament se n'agrupava la majoria dins O. palustris. És possible que se'n reconeguin noves espècies en el futur. El nom Oryzomys fou encunyat per Spencer Fullerton Baird el 1857 per O. palustris i aviat fou aplicat a més d'un centenar d'espècies de rosegadors americans. Posteriorment, el gènere anà sent redefinit amb criteris més estrictes fins que el seu contingut actual fou establert el 2006, quan es crearen deu nou gèneres per espècies antigament classificades dins d'Oryzomys.
Die Reisratten (Oryzomys) sind eine auf dem amerikanischen Kontinent lebende Nagetiergattung aus der Gruppe der Neuweltmäuse. Sie umfassen 43 Arten.
Reisratten erreichen eine Kopfrumpflänge von 9 bis 20 Zentimetern, der Schwanz ist 8 bis 25 Zentimeter lang und das Gewicht beträgt 40 bis 80 Gramm. Ihr raues, aber nicht stacheliges Fell ist an der Oberseite graubraun gefärbt, die Unterseite ist weiß oder hellbraun. Der Schwanz ist relativ lang und spärlich behaart.
Reisratten sind auf dem amerikanischen Kontinent von den mittleren USA bis in das nördliche Argentinien verbreitet, die größte Artenvielfalt herrscht jedoch in Mittel- und dem nördlichen Südamerika. Sie kommen sowohl in Wäldern wie auch in Sümpfen, Wiesen und sogar Gebirgsregionen vor.
Die Lebensweise ist nur von wenigen Arten, insbesondere O. palustris, bekannt. Diese Art errichtet Grasnester und ist sowohl tag- wie auch nachtaktiv. In trockenen Regionen gräbt sie auch Baue, sie kann außerdem gut schwimmen und sucht auch im Wasser nach Nahrung.
Ihre Nahrung besteht aus Gräsern, Samen und Früchten, aber auch Insekten, Krebstieren und kleinen Fischen.
Mehrmals im Jahr bringt das Weibchen nach einer 25- bis 28-tägigen Tragzeit zwei bis fünf Jungtiere zur Welt.
Einige Reisrattenarten sind weitverbreitet, sie fallen bisweilen in Plantagen ein und gelten als Schädlinge. Einige andere Arten sind in ihrem Bestand bedroht. Zwei Inselendemiten, O. curasoe (endemisch auf Curaçao) und O. nelsoni (endemisch auf den Marias-Inseln), sind ausgestorben.
Die Systematik und Artenzahl der Reisratten ist umstritten. Wilson und Reeder (2005) listen folgende 43 Arten:
Die Galápagos-Reisratten (Nesoryzomys) und die Dunklen Reisratten (Melanomys) werden manchmal in diese Gattung gegliedert.
Nach Weksler et al. (2006) sind die Reisratten keine natürliche Gruppe, die Arten sind teilweise näher mit anderen Neuweltmäusen verwandt als miteinander. Sie führen darum zehn neue Gattungen ein:
Oryzomys umfasst in diesem Sinn nur mehr wenige Arten wie O. palustris und O. cuesi. Sechs Arten werden in die bereits existierende Gattung Handleyomys übertragen.
Diese Aufteilung ist aber noch nicht allgemein anerkannt.
Die Reisratten (Oryzomys) sind eine auf dem amerikanischen Kontinent lebende Nagetiergattung aus der Gruppe der Neuweltmäuse. Sie umfassen 43 Arten.
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.
Species of Oryzomys are medium-sized rats with long, coarse fur. The upperparts are gray to reddish and the underparts white to buff. The animals have broad feet with reduced or absent ungual tufts of hair around the claws and, in at least some species, with webbing between the toes. The rostrum (front part of the skull) is broad and the braincase is high. Both the marsh rice rat and O. couesi have 56 chromosomes, lack a gall bladder, and have a complex penis (as is characteristic of the Sigmodontinae) with some traits that are rare among oryzomyines; these characteristics are unknown in the other species of this genus.
The habitat includes various kinds of wetlands, such as lakes, marshes, and rivers. Oryzomys species swim well, are active during the night, and eat both plant and animal food. They build woven nests of vegetation. After a gestation period of 21 to 28 days, about four young are born. Species of Oryzomys are infected by numerous parasites and carry at least three hantaviruses, one of which (Bayou virus) also infects humans. Two, maybe three, species have gone extinct over the last two centuries and at least one other is endangered, but the widespread marsh rice rat and O. couesi are not threatened.
Oryzomys is one of about thirty genera within the tribe Oryzomyini, a diverse group of well over a hundred species, many of which were formerly also included in Oryzomys.[9] Oryzomyini is one of several tribes within the subfamily Sigmodontinae of the family Cricetidae, which includes hundreds of other species of mainly small rodents, distributed mainly in the Americas and Eurasia.[10]
Within Oryzomyini, a 2006 phylogenetic analysis by Marcelo Weksler which used both morphological and DNA sequence data found some evidence that Oryzomys is most closely related to a group including Holochilus, Lundomys, and Pseudoryzomys. Although analyses based on morphological and combined data supported this relationship, sequences of the Rbp3 gene alone instead placed Oryzomys among a group that included Nectomys, Sigmodontomys, and a few other genera. In all analyses, Oryzomys appeared within clade D of Oryzomyini.[11] The relationship between Oryzomys and the Holochilus group was supported by five synapomorphies (shared derived characters)—absence or reduction of both the hypothenar and interdigital pads; reduction of ungual tufts of hairs surrounding the claws; having the back margin of the zygomatic plate of the skull at the same level as the front of the first upper molar; and the anterocone (front cusp) of the first upper molar divided by an anteromedian fossette. The first three are adaptations to the semiaquatic lifestyle that Oryzomys and the members of the Holochilus group share, and may thus be examples of convergent evolution.[12]
The name Oryzomys was introduced in 1857 by Spencer Fullerton Baird for the marsh rice rat (now Oryzomys palustris) of the eastern United States,[13] which had been first described twenty years earlier by Richard Harlan.[8] The name combines the Greek oryza "rice" and mys "mouse" and refers to the feeding habits of the marsh rice rat.[14][15] Baird placed Oryzomys as a subgenus of the now-defunct genus Hesperomys and included only the marsh rice rat in it, a classification which was followed by Elliott Coues in 1874 and 1877.[16] In 1890, Oryzomys was raised to generic rank, and in subsequent years numerous additional species were ascribed to it, many of which were soon moved to separate genera.[17] In the 1898 Catalogus Mammalium, Édouard Louis Trouessart listed 67 species of Oryzomys,[18] including some that are now placed in Calomys, Necromys, Thomasomys, and other genera unrelated to Oryzomys.[19] Some of the new genera proposed were soon subsumed in Oryzomys again,[20] and in The Families and Genera of Living Rodents (1941), John Ellerman listed Microryzomys, Oligoryzomys, Melanomys, Nesoryzomys, and Oecomys as synonyms of Oryzomys[21] and included about 127 species in it.[22] In 1948, Philip Hershkovitz suggested that other oryzomyines like Nectomys and Megalomys could as well be included in Oryzomys,[23] and Clayton Ray followed this suggestion in 1962.[24]
Hershkovitz and Ray's classification was never widely followed, and from 1976 on authors started to reinstate some of the other groups lumped in Oryzomys as separate genera.[25] The genus was reduced to 43 species (out of 110 in Oryzomyini) in the third edition (2005) of Mammal Species of the World,[26] but it was still not a natural, monophyletic group;[27] rather, it mostly united those oryzomyines that lacked the conspicuous specializations of other genera.[28] In 2006, Marcelo Weksler's comprehensive phylogenetic analysis produced further evidence that the genus was polyphyletic, as species of Oryzomys were dispersed all over the oryzomyine tree. He proposed that eleven new genera should be created to accommodate those species that were not closely related to the type species of Oryzomys, the marsh rice rat;[29] he considered other options that would require fewer new genera, but argued that that would result in less meaningful genus-level groups in Oryzomyini.[30] Later in the same year, Weksler, Percequillo, and Voss created ten new genera—Aegialomys, Cerradomys, Eremoryzomys, Euryoryzomys, Hylaeamys, Mindomys, Nephelomys, Oreoryzomys, Sooretamys, and Transandinomys—for species formerly placed in Oryzomys and placed six more species related to "Oryzomys" alfaroi in Handleyomys pending the description of more new genera for them.[31] They left only five species in Oryzomys, which was now finally a natural, monophyletic group. Because of subsequent taxonomic work, the number of species has since increased to at least eight.[32]
Some problems remain: ?Oryzomys pliocaenicus, a Miocene fossil from Kansas, is of uncertain identity but may belong in Bensonomys,[33] and fossils from the Miocene of Oregon and Pliocene of New Mexico have also been ascribed to Oryzomys, but probably incorrectly.[33] A possible Oryzomys has been recorded from the Irvingtonian (Pleistocene) of Saskatchewan.[34]
The current concept of Oryzomys derives from the palustris-mexicanus group recognized within a much larger genus Oryzomys by Merriam (1901) and the palustris group proposed by Goldman (1918).[1] Merriam recognized 21 species within his group, but Goldman consolidated them into eight—the marsh rice rat in the United States, O. couesi in far southern Texas, Mexico, and Central America, and six others with small distributions.[37] In 1960, Raymond Hall united O. couesi and the marsh rice rat into a single species, Oryzomys palustris, and thereafter, other localized forms were also included in O. palustris.[38] Hershkovitz described another species in the group, O. gorgasi from Colombia, in 1970[39] and the next year he noted that O. dimidiatus, previously classified as a Nectomys, was similar to O. palustris.[40] After 1979, the marsh rice rat and O. couesi were again regarded as separate as a result of further work in Texas, where their ranges meet.[38] While reviewing O. gorgasi in 2001, J. Sánchez H. and colleagues redefined and characterized the O. palustris group and listed O. couesi, O. dimidiatus, O. gorgasi, and the marsh rice rat as its members;[41] Guy Musser and Michael Carleton in the 2005 third edition of Mammal Species of the World additionally listed O. nelsoni from María Madre Island in western Mexico.[8]
In 2006, Weksler and colleagues followed the 2001 definition by Sánchez and others for the restricted genus Oryzomys, but added O. antillarum from Jamaica as a species.[42] Carleton and Joaquin Arroyo-Cabrales reviewed Oryzomys from western Mexico in 2009 and in this context provided an extended diagnosis of Oryzomys. They recognized eight species: the six previously mentioned plus O. albiventer and O. peninsulae.[1] Also in 2009, Robert Voss and Weksler identified the subfossil Oryzomys curasoae from Curaçao as an island population of O. gorgasi.[43] The next year, Delton Hanson and colleagues published a study using DNA sequence data from the cytochrome b, interphotoreceptor retinoid-binding protein, and alcohol dehydrogenase 1 genes to assess relationships within Oryzomys. They recommended that the marsh rice rat be split into two species and that O. couesi be split into four species on the basis of the observed sequence divergence and other data.[44]
Merriam divided his palustris-mexicanus group in two "series" according to the color of the underparts (white or fulvous).[45] Goldman divided his palustris group in two "sections"—a couesi section with O. couesi and six related species, and a palustris section with O. palustris only. He noted that the latter differed from the former in the generally darker, more brownish, longer fur, and larger sphenopalatine vacuities (openings in the mesopterygoid fossa, the gap behind the end of the palate).[46] As Weksler's 2006 analysis included only O. couesi and the marsh rice rat among species of Oryzomys in the strict sense, he could not test those groups.[47] Carleton and Arroyo-Cabrales concurred with Goldman's division, listing additional characters, and noted that the palustris group may be more semiaquatically adapted than the members of the couesi group are. In the latter, the fur is usually reddish-brown, as opposed to grayish-brown in the palustris group. Members of the couesi group have smaller sphenopalatine vacuities and a smaller sphenopalatine foramen, a foramen (opening) in the side of the skull above the molars, and a more highly developed anterolabial cingulum on the third lower molar (a crest at the front of the tooth). The hypothenar pad of the hindfoot, located on the sole far from the fingers, is present in the couesi group, but absent in the palustris group. Interdigital webbing may be more highly developed in the palustris group.[36] Using morphological data, Voss and Weksler found a closer relationship between O. couesi and O. gorgasi to the exclusion of O. palustris, but with low confidence.[48] The DNA sequence data of Hanson and colleagues supported a deep separation between the palustris and couesi groups, but a Costa Rican sample (assigned to O. couesi) was about as distant from the two groups as they were from each other.[49]
The genus currently includes the following species:[1]
Oryzomys contains medium-sized, semiaquatically specialized oryzomyine rodents. They have long, coarse fur that is grayish to reddish on the upperparts and white to buff on the underparts.[76] The marsh rice rat superficially resembles the introduced species black rat and brown rat, but has larger differences in color between the upper- and underparts.[75] The vibrissae (whiskers) are short and the ears are small and well-haired. The tail is usually as long as or longer than the head and body and is sparsely haired, but the hairs on the lower side are longer than those above. Females have eight mammae, as in most oryzomyines. The hindfeet are broad and have the first and fifth digits notably shorter than the middle three. The upper surface is hairy, but the underside is naked and covered with small irregularities (squamae). The pads are generally poorly developed, as are the ungual tufts.[77] Interdigital webbing may be present, but its development is variable within the genus.[36]
The karyotype has been recorded in various populations of the marsh rice rat and O. couesi and is apparently stable within the genus at 56 chromosomes, with the fundamental number of chromosomal arms ranging from 56 to 60 (2n = 56, FN = 56–60).[44] In both species, the stomach has the characteristic pattern of sigmodontines (unilocular-hemiglandular): it is not split in two chambers by an incisura angularis and the front part (antrum) is covered by a glandular epithelium.[78] Furthermore, the gall bladder is absent, a synapomorphy of Oryzomyini.[79]
Oryzomys species have a large skull with a short rostrum and high braincase. The interorbital region, located between the eyes, is narrowest to the front and is flanked by well-developed beads at its margins. The zygomatic plate is broad and has a well-developed zygomatic notch at its front. The zygomatic arch is robust and contains a small but distinct jugal bone. The interparietal bone, part of the roof of the braincase, is narrow and short;[81] its narrowness is a synapomorphy for O. couesi plus the marsh rice rat according to Weksler's analysis.[12] The incisive foramina are long, with their back margin at the front of the first molars or further back. The palate is also long, extending beyond the back margin of the maxillary bone, and is perforated near the third molars by well-developed posterolateral palatal pits. There is no alisphenoid strut, an extension of the alisphenoid bone that in some other oryzomyines separates two foramina in the skull. The auditory bullae are large. The condition of the arteries in the head is highly derived.[81] In the mandible (lower jaw), the coronoid process, a process at the back, is well developed[82] and the capsular process, a raising of the mandibular bone housing the root of the lower incisor, is conspicuous.[46]
As usual in oryzomyines, the molars are pentalophodont (have the mesolophs and mesolophids, accessory crests, well developed) and bunodont, with the cusps higher than the connecting crests.[1] The cusps on the upper molars are arranged in two longitudinal series, not three as in the black and brown rats.[83] The front cusps of the first upper and lower molar (anterocone and anteroconid, respectively) are broad and not divided completely by an anteromedian flexus or flexid. Behind the anterocone, the anteroloph (a smaller crest) is complete and separated from the anterocone.[1] On both the second and third lower molars, the anterolophid (a crest on the inner front corner) is present, a putative synapomorphy of the genus.[12] The first molars have additional small roots in addition to the main ones, so that the upper first molar has four and the lower has three or four roots.[1]
As is characteristic of Sigmodontinae, the marsh rice rat and O. couesi have a complex penis, with the baculum (penis bone) displaying large protuberances at the sides.[84] The outer surface of the penis is mostly covered by small spines, but there is a broad band of nonspinous tissue.[85] The papilla (nipple-like projection) on the dorsal (upper) side of the penis is covered with small spines, a character these two species share only with Oligoryzomys among oryzomyines examined.[86] On the urethral process, located in the crater at the end of the penis,[87] a fleshy process (the subapical lobule) is present; it is absent in all other oryzomyines with studied penes except Holochilus brasiliensis.[88] Both traits are recovered as synapomorphies of O. couesi plus the marsh rice rat in Weksler's analysis.[12]
The range of Oryzomys extends from New Jersey in the eastern United States through Mexico and Central America south to northwestern Colombia and east to northwestern Venezuela and Curaçao.[90] Species of Oryzomys usually live in wet habitats such as marshes, streams, and mangroves,[1] but both the marsh rice rat and O. couesi are also occasionally encountered in drier habitats.[91] They occur or occurred on many continental-shelf islands and one oceanic island, Jamaica; their adeptness at colonizing islands may be caused by their close association with water and frequent occurrence in coastal wetlands.[69] The oldest fossils date to the Rancholabrean of the United States, about 300,000 years ago; although there have been some earlier North American records, those are not in fact referable to Oryzomys or even Oryzomyini.[92] Oryzomyines likely evolved in South America east of the Andes; the presence of Oryzomys in Central America and other trans-Andean regions is thought to be the result of one of several independent invasions of this region by oryzomyines.[93] Alternatively, Oryzomys may have evolved from the Pliocene North American Jacobsomys.[94] O. antillarum may have reached Jamaica during the last glacial period while sea levels were low.[52]
Behavior is known mainly from the marsh rice rat and O. couesi, with some scattered data from the other species. Oryzomys are semiaquatic, spending much time in the water, and otherwise mainly live on the ground;[95] both the marsh rice rat and O. couesi are known to be excellent swimmers and will flee into the water when disturbed.[96] Both are also active during the night and build nests of interwoven vegetation, which may be suspended above the water.[97] Breeding may occur throughout the year in both species, but is known to be seasonally variable in the marsh rice rat.[98] In both, gestation takes about 21 to 28 days and litter size is usually one to seven, averaging three to five.[99] Young marsh rice rats and O. couesi become reproductively active when about 50 days old.[100]
The marsh rice rat, O. couesi, and O. gorgasi are known to be omnivores, eating both plant and animal material. They eat both seeds and green plant parts and consume a variety of animals, including insects, crustaceans, and many others.[101] The barn owl (Tyto alba) is a major predator on the marsh rice rat[102] and remains of O. antillarum, O. couesi, and O. gorgasi have been found in owl pellet deposits.[103] Several other animals are known to prey on Oryzomys.[104] A variety of parasites are known from O. couesi[105] and the marsh rice rat[106] and two parasitic nematodes have been found in O. gorgasi.[107]
Two species of Oryzomys, O. antillarum and O. nelsoni, have gone extinct since the 19th century,[108] and a third, O. peninsulae, is unlikely to be still extant.[69] Their extinction may have been caused by habitat destruction and by introduced species such as the small Asian mongoose and the brown and black rat.[109] These same causes may threaten O. gorgasi, which the IUCN Red List assesses as "Endangered".[110] O. albiventer has been affected by human alteration of its habitat, but likely still survives.[111] In contrast, the widespread species, the marsh rice rat and O. couesi, are common and of no conservation concern—indeed, both have been considered a pest—but some populations are threatened.[112] Like these two species, O. dimidiatus is assessed as "Least Concern" by the Red List.[113]
The marsh rice rat is the natural reservoir of the Bayou virus, the second most common cause of hantavirus pulmonary syndrome in the United States.[114] Two other hantaviruses, Catacamas virus and Playa de Oro virus, occur in O. couesi in Honduras and western Mexico, respectively, but are not known to infect humans.[115]
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.
Species of Oryzomys are medium-sized rats with long, coarse fur. The upperparts are gray to reddish and the underparts white to buff. The animals have broad feet with reduced or absent ungual tufts of hair around the claws and, in at least some species, with webbing between the toes. The rostrum (front part of the skull) is broad and the braincase is high. Both the marsh rice rat and O. couesi have 56 chromosomes, lack a gall bladder, and have a complex penis (as is characteristic of the Sigmodontinae) with some traits that are rare among oryzomyines; these characteristics are unknown in the other species of this genus.
The habitat includes various kinds of wetlands, such as lakes, marshes, and rivers. Oryzomys species swim well, are active during the night, and eat both plant and animal food. They build woven nests of vegetation. After a gestation period of 21 to 28 days, about four young are born. Species of Oryzomys are infected by numerous parasites and carry at least three hantaviruses, one of which (Bayou virus) also infects humans. Two, maybe three, species have gone extinct over the last two centuries and at least one other is endangered, but the widespread marsh rice rat and O. couesi are not threatened.
Oryzomys es un género de mamíferos roedores de la familia Cricetidae, llamados comúnmente ratones de arrozal por los estragos que producen en los campos de arroz.
Su vida se desarrolla en estrecha relación con el agua y nadan y se sumergen con facilidad. Habitan en zonas húmedas y pantanosas. Construyen sus nidos de material vegetal y sobre la vegetación, al nivel máximo del agua. Las hembras tienen repetidas gestaciones de 25 días, al cabo de los cuales paren tres o cuatro crías.
Se alimentan de semillas, hierbas, frutas, insectos, crustáceos y pequeños peces. La talla varía según la especie. El cuerpo mide de 9 a 20 cm de longitud más una cola de 8 a 25 cm de largo; el peso varía entre 40 y 80 gramos.
De acuerdo con estudios filogenéticos, el conjunto de especies que se había incluido en Oryzomys es polifilético. Por ejemplo, O. intectus ha sido trasladado a un nuevo género, Handleyomys, pero otras especies siguen clasificadas como Oryzomys.
Con seguridad forman parte de este género:
Se realizan estudios para reclasificar o ratificar la clasificación de:
Oryzomys es un género de mamíferos roedores de la familia Cricetidae, llamados comúnmente ratones de arrozal por los estragos que producen en los campos de arroz.
Oryzomys Cricetidae animalia familiako generoa da[1], karraskarien barruan sailkatua.
Oryzomys Cricetidae animalia familiako generoa da, karraskarien barruan sailkatua.
Rats du riz
les rats du riz (Oryzomys) sont un genre de rongeurs de la famille des Cricétidés, vivant en Amérique du Nord, en Amérique centrale et au nord de l'Amérique du Sud et dont le plus connu des francophones est l'Oryzomys palustre (Oryzomys palustris). Dans la classification phylogénétique, ce genre fait partie de la tribu des Oryzomyini.
Les deux espèces les plus courantes, Oryzomys couesi et Oryzomys palustris, sont des animaux nocturnes, des rats semi-aquatiques. Ils ont un pelage grossier, une longue queue, un dos brun et un ventre blanc. Ils se nourrissent de graines, de plantes et d'invertébrés. La longueur tête-corps est de 190 à 410 mm, la longueur de la queue est de 85 à 140 mm et le poids de 40 à 80 g. Ces deux espèces occupent la plupart du territoire du genre, avec O. palustris vivant dans une grande partie de l'est des États-Unis et O.couesi dans une grande partie de l'Amérique centrale et du Mexique, se prolongeant au Texas vers le nord et la Colombie vers le sud. Les six autres espèces ont des territoires plus restreints: les espèces disparues O. antillarum et O. nelsoni vivaient respectivement sur la Jamaïque et les Îles Marías; O. dimidiatus vit dans le sud-est du Nicaragua; O. peninsulae vit à la pointe sud de la péninsule de Baja California, mais est peut-être déjà éteint; O. albiventer se rencontre dans les montagnes du Mexique occidental et O. gorgasi se rencontre dans le nord de la Colombie et au Venezuela et autrefois aussi sur l'île voisine de Curaçao.
Le nom du genre Oryza vient du latin, «riz», et mys du grec (μῦς) «souris».[réf. nécessaire]
« Rats du riz » est le nom vernaculaire donné en français aux rongeurs du genre Oryzomys. On ne doit pas confondre ces espèces avec le rat des rizières (Rattus argentiventer).
Liste alphabétique des noms vernaculaires attestés en français.
Note : certaines espèces ont plusieurs noms.
Bien que le genre contienne aujourd'hui environ huit espèces, de nombreux autres espèces y ont été précédemment installées comme des membres de genres désormais considérés comme sans rapport avec lui, tel le genre Thomasomys. La plupart des autres rats consommant du riz ont également été placés préalablement dans le genre Oryzomys. Dans l'édition 2005 des Mammal Species of the World, le genre contient encore plus de 40 espèces, mais il était alors clair que le genre était polyphylétique; dans les arbres phylogénétiques, ses membres semblent dispersés dans toute la tribu Oryzomyini. En conséquence, la plupart des espèces ont été retirées du genre Oryzomys dans un document de 2006 de l’American Museum Novitates dû à Marcelo Weksler et collaborateurs. Ils ont décrit 10 genres nouveaux (Aegialomys, Cerradomys, Eremoryzomys, Euryoryzomys, Hylaeamys, Mindomys, Nephelomys, Oreoryzomys, Sooretamys et Transandinomys) pour les espèces précédemment mises dans Oryzomys et déplacé certaines autres espèces vers le genre Handleyomys dans l'attente de la description de nouveaux genres. Deux autres espèces, Oryzomys anoblepas et Oryzomys hypenemus, n'ont pas été évaluées dans des études récentes et leur statut demeure incertain. Le genre est maintenant probable monophylétique, bien que certains problèmes taxonomiques restent.
Selon Mammal Species of the World (version 3, 2005) (14 févr. 2011)[3] :
Selon NCBI (14 févr. 2011)[4] :
Selon ITIS (14 févr. 2011)[5] :
Rats du riz
les rats du riz (Oryzomys) sont un genre de rongeurs de la famille des Cricétidés, vivant en Amérique du Nord, en Amérique centrale et au nord de l'Amérique du Sud et dont le plus connu des francophones est l'Oryzomys palustre (Oryzomys palustris). Dans la classification phylogénétique, ce genre fait partie de la tribu des Oryzomyini.
Oryzomys (Baird, 1857) è un genere di roditori della famiglia dei Cricetidi comunemente noti come topi delle risaie.
Al genere Oryzomys appartengono roditori di piccole dimensioni, con lunghezza della testa e del corpo tra 93 e 203 mm, la lunghezza della coda tra 75 e 251 mm e un peso fino a 80 g.[1]
Il cranio è robusto e provvisto di un rostro corto e compatto, le arcate zigomatiche sono relativamente basse, il palato si estende posteriormente oltre le radici dentarie ed è provvisto di fori palatali. La bolla timpanica relativamente piccola e rigonfia. La mandibola è ben sviluppata. Gli incisivi superiori sono notevolmente opistodonti, ovvero con le punte rivolte verso l'interno della bocca, i molari hanno la corona bassa.
Sono caratterizzati dalla seguente formula dentaria:
3 0 0 1 1 0 0 3 3 0 0 1 1 0 0 3 Totale: 16 1.Incisivi; 2.Canini; 3.Premolari; 4.Molari;La pelliccia è corta, densa e leggermente ruvida, le parti dorsali variano dal bruno-grigiastro brizzolato al fulvo giallastro, i fianchi sono più chiari mentre le parti ventrali sono biancastre o grigie. Il muso è lungo ed appuntito. Le orecchie sono piccole ed arrotondate. I piedi sono lunghi e stretti, con le piante ricoperte di scaglie e munite di sei cuscinetti carnosi nerastri, le tre dita centrali del piede sono molto più lunghe di quelle esterne, sono leggermente palmate e fornite di una frangia di peli sul margine esterno. Alla base di ogni artiglio è presente un ciuffo di peli. La coda è più lunga della testa e del corpo, sottile, più scura sopra e cosparsa di peli che talvolta formano un piccolo ciuffo all'estremità. Le femmine hanno 4 paia di mammelle.
Il genere è diffuso nel continente americano, dagli Stati Uniti d'America, attraverso tutta l'America centrale fino alla Colombia e al Venezuela settentrionali.
Il genere comprende 6 specie.[2]
Oryzomys (Baird, 1857) è un genere di roditori della famiglia dei Cricetidi comunemente noti come topi delle risaie.
Ryžiniai žiurkėnai (lot. Oryzomys, angl Rice rats, vok. Reisratten) – žiurkėninių (Cricetidae) šeimos graužikų gentis. Paplitę Pietų ir Centrinėje Amerikoje, Meksikoje, Galapagų salose.
Gentyje yra apie 57 rūšys.
Oryzomys is een geslacht van knaagdieren uit de Oryzomyini. De 8 soorten komen voor van het zuiden van Noord-Amerika tot het uiterste noorden van Zuid-Amerika.
Het geslacht kent de volgende soorten
Oryzomys is een geslacht van knaagdieren uit de Oryzomyini. De 8 soorten komen voor van het zuiden van Noord-Amerika tot het uiterste noorden van Zuid-Amerika.
Multimedia w Wikimedia Commons Ryżniak[4] (Oryzomys) – rodzaj ssaka z podrodziny bawełniaków (Sigmodontinae) w rodzinie chomikowatych (Cricetidae).
Rodzaj obejmuje gatunki występujące w Ameryce[4][5].
Do rodzaju należą następujące gatunki[4][5]:
Ryżniak (Oryzomys) – rodzaj ssaka z podrodziny bawełniaków (Sigmodontinae) w rodzinie chomikowatych (Cricetidae).
Oryzomys é um gênero de roedores da família Cricetidae distribuído na América do Norte, Central e norte da América do Sul.
Musser e Carleton (2005) aceitam 43 espécies pertencentes ao gênero Oryzomys, entretanto, estudos filogenéticos prévios já demonstravam o gênero como polifilético. Em 2006, Weksler e colaboradores descrevem 10 novos gêneros (Aegialomys, Cerradomys, Eremoryzomys, Euryoryzomys, Hylaeamys, Mindomys, Nephelomys, Oreoryzomys, Sooretamys e Transandinomys), desmembrando o gênero Oryzomys.
Oryzomys é um gênero de roedores da família Cricetidae distribuído na América do Norte, Central e norte da América do Sul.
Risråttor (Oryzomys) är ett släkte gnagare i familjen hamsterartade gnagare (Cricetidae) som förekommer i Amerika. De är alltså inte närmare släkt med de egentliga råttorna (Rattus).
Risråttor når en kroppslängd mellan 9 och 20 cm, en svanslängd mellan 8 och 25 cm samt en vikt mellan 40 och 80 gram. Pälsen är grov men inte taggig. Den har på ovansidan en gråbrun färg och är på undersidan vitaktig eller ljusbrun. Svansen är bara glest täckt med hår.[1]
Dessa gnagare förekommer i Amerika från centrala USA till norra Argentina, de flesta arterna finns i Centralamerika och norra Sydamerika. Habitatet varierar mellan skogar, träskmark, gräsmark och klippiga bergstrakter med buskar.[1]
För de flesta arterna är levnadssättet okänt. Mera bekant O. palustris är som bygger bon av gräs och som kan vara aktiv på dagen eller på natten. I torra regioner gräver den underjordiska bon. Dessutom har arten bra simförmåga och hittar födan delvis i vattnet.
Allmänt utgörs födan av gräs, frön, frukter samt även insekter, kräftdjur och små fiskar.[1]
Honan kan para sig flera gångar per år och efter 25 till 28 dagars dräktighet föds två till fem ungar per kull.[1]
De flesta arterna är inte sällsynta och de betraktas ofta som skadedjur när de äter odlade växter. Några arter är hotade enligt IUCN:s rödlista.[2] Två arter som var endemiska på öar är redan utdöd: O. curasoe (på Curaçao) och O. nelsoni (på Islas Marías).[3]
Risråttornas systematik och antalet arter är omstridd. Wilson & Reeder (2005) skiljer mellan 43 arter:[4]
Vissa taxonomiska av handlingar räknar även Galapagosrisråttor (Nesoryzomys) och släktet Melanomys till risråttorna.
Enligt en studie av Weksler et al. (2006) är risråttor ingen monofyletisk grupp. Här framhållas att vissa arter är närmare släkt med andra gnagare från nya världen än med de andra risråttorna. Forskarlaget introducerade tio nya släkten:[5]
I släktet Oryzomys blir bara ett fåtal arter kvar, till exempel O. palustris och O. cuesi. Sex arter överföras till släktet Handleyomys som etablerades tidigare.
Wikimedia Commons har media som rör Risråttor.
Risråttor (Oryzomys) är ett släkte gnagare i familjen hamsterartade gnagare (Cricetidae) som förekommer i Amerika. De är alltså inte närmare släkt med de egentliga råttorna (Rattus).
Ареал Oryzomys простягається від Нью-Джерсі в східній частині Сполучених Штатів через Мексику і Центральну Америку на південь до північно-західної Колумбії і зі сходу на північному заході Венесуели і Кюрасао. Рисові хом'яки живуть в різноманітних лісових, чагарникових і гірських ландшафтах, але більшість воліє сирі, болотисті місця в дикій природі. За рідкісним винятком у будівлі людини вони не проникають.
Гризуни ззовні схожі на великих мишей. Довжина тіла 10-20 см, вага 30-80 г. Хвіст приблизно дорівнює довжині тіла.
Рисові хом'яки активні в будь-який час доби. Звичайно кілька годин підвищеної активності перериваються короткочасним відпочинком. Притулки ці хом'яки можуть влаштовувати в неглибоких норах, частіше на поверхні землі під прикриттям поваленого дерева, між коріння або в каменях. На болотах гніздо з сухої трави (куля до півметра в діаметрі з входом збоку або знизу) часто поміщається в гілках густого чагарнику, серед стебел і трав або на високій купині. Зсередини гніздо вистилають тонкими травинками і рослинним пухом.
Незважаючи на добре виражену горбкувату насіннєїдну структуру жувальних зубів, ці гризуни у великій кількості споживають соковиту зелень трав і молодих пагонів дерев і чагарників, при нагоді із задоволенням їдять рибу. Самі вони піймати її не можуть, хоча добре плавають і пірнають, і задовольняються загиблою або доїдають чужі залишки. Рисові хом'яки регулярно живляться комахами та іншими безхребетними.
У тропічних широтах розмноження триває цілий рік, а в помірних областях і високо в горах — з невеликою перервою. Через 25 діб вагітності самка народжує 3 — 4 (рідко 7 — 8) дитинчат. Новонароджені мають вагу від 2 до 5 г кожен залежно від розмірів самки і абсолютно безпорадні. Перший час вони голі й сліпі. Через два тижні дитинчата переходять на рослинні корми, а в два місяці починають розмножуватися. Всі самки майже цілий рік вагітні, кожна з них дає по 8 — 10 приплодів. У природі величезна кількість рисових хом'яків гине від хижаків і хвороб, і тільки їх плодючість компенсує втрати. Рідкісні особини доживають до року. Рисових хом'яків розводять у лабораторіях для досліджень з біології та медицині.
Oryzomys là một chi động vật có vú trong họ Cricetidae, bộ Gặm nhấm. Chi này được Baird miêu tả năm 1857.[1] Loài điển hình của chi này là Mus palustris Harlan, 1837.
Chi này gồm các loài:
Bài viết liên quan đến phân họ gặm nhấm Sigmodontinae này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn. Oryzomys là một chi động vật có vú trong họ Cricetidae, bộ Gặm nhấm. Chi này được Baird miêu tả năm 1857. Loài điển hình của chi này là Mus palustris Harlan, 1837.
Oryzomys Baird, 1857
Ареал
Рисовые хомяки (лат. Oryzomys) — род мышевидных грызунов из семейства хомяковые (Cricetidae). Ранее род насчитывал более 100 видов. Сейчас к роду относят 8 видов, из которых 3 вида вымерли в исторический период[1].
Ареал Oryzomys простирается от Нью-Джерси в восточной части Соединённых Штатов через Мексику и Центральную Америку на юг до северо-западной Колумбии и с востока на северо-запад Венесуэлы и Кюрасао[2]. Рисовые хомяки живут в различных лесных, кустарниковых и горных ландшафтах, но большинство предпочитает сырые, болотистые места в дикой природе. За редким исключением в жилища человека они не проникают.
Грызуны внешне похожи на больших мышей. Длина тела 10—20 см, вес 30—80 г. Хвост примерно равен длине тела.
Рисовые хомяки активны в любое время суток. Обычно несколько часов повышенной активности прерываются кратковременным отдыхом. Укрытия эти хомяки могут устраивать в неглубоких норах, чаще на поверхности земли под прикрытием поваленного дерева, между корней или в камнях. На болотах гнездо из сухой травы (шар до полуметра в диаметре с входом сбоку или снизу) часто помещается в ветвях густого кустарника, среди стеблей и трав или на высокой кочке. Изнутри гнездо выстилают тонкими травинками и растительным пухом[3].
Несмотря на хорошо выраженную холмистую структуру жевательных зубов, эти грызуны в большом количестве потребляют сочную зелень трав и молодых побегов деревьев и кустарников, при случае с удовольствием едят рыбу. Сами они поймать её не могут, хотя хорошо плавают и ныряют, и удовлетворяются погибшей или доедают чужие остатки. Рисовые хомяки регулярно питаются насекомыми и другими беспозвоночными.
В тропических широтах размножение длится круглый год, а в умеренных областях и высоко в горах — с небольшим перерывом. Через 25 суток беременности самка рождает 3—4 (редко 7—8) детёнышей[4]. Новорожденные весят от 2 до 5 г каждый в зависимости от размеров самки и совершенно беспомощны. Первое время они голые и слепые. Через две недели детёныши переходят на растительные корма, а в два месяца начинают размножаться. Все самки почти круглый год беременны, каждая из них даёт по 8—10 помётов. В природе огромное количество рисовых хомяков погибает от хищников и болезней, и только их плодовитость компенсирует потери. Редкие особи доживают до года. Рисовых хомяков разводят в лабораториях для исследований по биологии и медицине.
Рисовые хомяки (лат. Oryzomys) — род мышевидных грызунов из семейства хомяковые (Cricetidae). Ранее род насчитывал более 100 видов. Сейчас к роду относят 8 видов, из которых 3 вида вымерли в исторический период.
Ареал Oryzomys простирается от Нью-Джерси в восточной части Соединённых Штатов через Мексику и Центральную Америку на юг до северо-западной Колумбии и с востока на северо-запад Венесуэлы и Кюрасао. Рисовые хомяки живут в различных лесных, кустарниковых и горных ландшафтах, но большинство предпочитает сырые, болотистые места в дикой природе. За редким исключением в жилища человека они не проникают.
見內文
稻鼠屬（Oryzomys）是倉鼠科（Cricetidae）之下的一個屬，最近系統發生學研究顯示，稻鼠屬是一個多系群（polyphyletic），也就是此分類群之下並不包含所有具共同祖先的相近物種，科學家因此在稻鼠屬之上加了一個更高層級的分類群，稱為稻鼠族（Oryzomyini）。而有些原本屬於稻鼠屬的物種，則被移動到稻鼠族中的新設屬之下。
稻鼠屬（Oryzomys）是倉鼠科（Cricetidae）之下的一個屬，最近系統發生學研究顯示，稻鼠屬是一個多系群（polyphyletic），也就是此分類群之下並不包含所有具共同祖先的相近物種，科學家因此在稻鼠屬之上加了一個更高層級的分類群，稱為稻鼠族（Oryzomyini）。而有些原本屬於稻鼠屬的物種，則被移動到稻鼠族中的新設屬之下。
쌀쥐속(Oryzomys)은 비단털쥐과 쌀쥐족에 속하는 준수생 설치류 속이다.[1] 북아메리카 남부부터 남아메리카 북부 사이에서 발견된다. 널리 분포하는 2종(미국에 서식하는 습지쌀쥐와 멕시코와 중앙아메리카에 서식하는 쿠스쌀쥐)과 좀더 제한적으로 분포하는 6종을 포함하여 모두 8종으로 이루어져 있다.
다음은 2006년 웩슬러 등(Weksler_et_al..)[2]의 연구에 기초한 계통 분류이다.
쌀쥐족우카얄리물쥐속, 맥코넬쌀쥐속, 핸들리쥐속, 큰머리쌀쥐속, 해먼드쌀쥐속, 톰스쌀쥐속,
나무쌀쥐속, 안데스횡단쌀쥐속
해안쌀쥐속, 세하두쌀쥐속, 흰반점산악쥐속, 회색쌀쥐속, 습지쥐속, 큰습지쥐속, 검은쌀쥐속,
남아메리카물쥐속, 갈라파고스쌀쥐속, 쌀쥐속, 브라질가짜쌀쥐속, 쌀물쥐속, 파라과이쌀쥐속
