page_title: Pseudoryzomys
section_title: Description
hierarchical_section_title: Pseudoryzomys / Description
caption_attribution_description: English: Marsh rice rat (Oryzomys palustris) in Paynes Prairie, Florida. This is presumably the subspecies O.&#160;p.&#160;natator, distinguished by more reddish fur.
context_page_description: Pseudoryzomys simplex, also known as the Brazilian false rice rat or false oryzomys, is a species of rodent in the family Cricetidae from south-central South America. It is found in lowland palm savanna and thorn scrub habitats. It is a medium-sized species, weighing about 50 grams, with gray–brown fur, long and narrow hindfeet, and a tail that is about as long as the head and body. The IUCN has assessed its conservation status as being of least concern, although almost nothing is known about its diet or reproduction.
  The only species in the genus Pseudoryzomys, its closest living relatives are the large rats Holochilus and Lundomys, which are semiaquatic, spending much of their time in the water. The three genera share several characters, including specializations towards a semiaquatic lifestyle, such as the presence of membranes between the digits, and a reduction in the complexity of the molar crowns, both of which are at incipient stages in Pseudoryzomys. Together, they form a unique assemblage within the oryzomyine tribe, a very diverse group including over one hundred species, mainly in South America.
context_section_description: Pseudoryzomys simplex is a nondescript, medium-sized rat with long, soft fur. The upperparts are gray–brown and the underparts are buff; the color changes gradually over the body. The small ears are covered with short hairs. The tail is as long as or slightly longer than the head and body, and is dark above and light below. Despite the presence of short hairs, the scales on the tail are clearly visible. The hairs on the feet are pale. The hindfeet are long and narrow and have five toes, the first and fifth of which are short. Webbing is present between the second, third, and fourth toes, but the membranes are not as large as in Lundomys or Holochilus. The tufts of hair on the toes and several of the pads are reduced, other common characteristics of semiaquatic oryzomyines. The head-body length is 94 to 140 millimeters (3.7 to 5.5 in), tail length 102 to 140 mm (4.0 to 5.5 in), hindfeet length 27 to 33 mm (1.1 to 1.3 in), ear length 13 to 19 mm (0.5 to 0.7 in) and body mass 45 to 55 g (1.6 to 1.9 oz).
  The female has four pairs of teats, including one on the chest and three on the belly, and the gall bladder is absent, both important characters of Oryzomyini. As is characteristic of Sigmodontinae, Pseudoryzomys has a complex penis, with the baculum (penis bone) displaying large protuberances at the sides. In the cartilaginous part of the baculum, the central digit is smaller than those at the sides.
caption: The marsh rice rat (Oryzomys palustris) of the eastern United States is similar in appearance to Pseudoryzomys.[8]
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