Cricetidae Author Don E. Wilson Author Russell A. Mittermeier Author Thomas E. Lacher, Jr text 2017 2017-11-30 Lynx Edicions Barcelona Handbook of the Mammals of the World – Volume 7 Rodents II 204 535 book chapter 80832 10.5281/zenodo.6707142 ab66b2b7-9544-4411-bf61-5bc3651d7bca 978-84-16728-04-6 6707142 481. Ucayali Water Rat Amphinectomys savamis French: Nectomys de I'Ucayali / German: Ucayali-Wasserratte / Spanish: Rata de agua de Ucayali Taxonomy. Amphinectomys savamis Malygin, 1994 , 7 km east Jenaro Herrera, right bank of Rio Ucayali ( 04°55 S , 73°45’ W ) in the province Requena, Department of Loreto , Peru (as translated from original in Russian ). Amphinectomys savamis is the type species of the genus. Monotypic. Distribution. SE Ecuador and NE Peru, known from five localities associated with N & S bank tributaries of Rio Maranon. Descriptive notes. Head-body 187-190 mm, tail 173-206 mm, ear 21-24 mm, hindfoot 53-54 mm; weight 214-225 g. The Ucayali Water Rat is large, similar to species of Nectomys , with tail longer than head-body length, long and robust hindfeet, and moderately short ears. Pelage is soft, shiny, and glossy, with long dorsal hair (length 22 mm) and dense underfur. Dorsum is dark brown to fulvous brown, sides are more ocherous, and venter is grayish white, with conspicuous countershading. Mystacial vibrissae are dense and very long, extending beyond pinnae when laid back. Pinnae are only slightly hairy and dark brown. Manus and pes are covered dorsally with short, pale hair. Second,third, and fourth digits on hindfeet are much longer than first and fifth digits. Large webs of skin are present on manus and pes between second, third, and fourth digits, extending to bases of claws. Pes has conspicuous white tufts of ungual hair at bases of claws on all digits; plantar surfaces are covered with squamae. Natatory fringes are present along medial plantar margins of metatarsus and first and second digits, and along lateral plantar margins of fourth and fifth digits. Tail is distinctly bicolored (dark above, pale below); tail scales are large; tail has conspicuous keel of hair on ventral surface; and apical tuft is present but inconspicuous. There are four pairs of mammae. Chromosomal complementis 2n = 50, FN = 66. Habitat. Moist forests. Peruvian Ucayali Water Rats are from Southwest Amazon moist forests, while the Ecuadorean record was from ecotonal region between Napo moist forest and Eastern Cordillera real montane forest. The Ucayali Water Rat has been trapped close to a small creek (0-5-1 m across, 0-5 m deep) in primary forest. Food and Feeding. No information. Breeding. No information. Activity patterns. Morphological adaptations of the Ucayali Water Rat suggests a highly specialized aquatic life. The original type was found in the forest at the edge ofa stream. Movements, Home range and Social organization. No information. Status and Conservation. Classified as Data Deficient on The IUCN Red List. Bibliography. Chiquito & Percequillo (2017), Malygin et al. (1994), Medina et al. (2015), Pacheco, Zeballos & Vivar (2008), Valqui (2001), Weksler & Valqui (2015). -Peters,1861