Gorgas's rice rat

Oryzomys gorgasi is a medium-sized oryzomyine with small ears and large feet, and is similar to the marsh rice rat in general appearance. The long and coarse fur is brownish above and ochraceous below. At the base of the tail, the upper and lower sides differ in color and at the end is a short tuft of hairs. The scales on the tail are well-developed. As in other Oryzomys, the hindfeet exhibit specializations for life in the water. The plantar (lower) surface of the metatarsus is naked. Two of the pads are very small. Ungual tufts, tufts of hair at the bases of the claws, are poorly developed. Interdigital webbing is present, but extends along less than half of the first phalanges. In specimens from El Caimito, total length is 220 to 290 mm (8.7 to 11.4 in), averaging 259 mm (10.2 in) (measured in 6 specimens); tail length is 116 to 138 mm (4.6 to 5.4 in), averaging 130 mm (5.1 in) (measured in 8 specimens); hindfoot length is 30 to 32 mm (1.2 to 1.3 in), averaging 31 mm (1.2 in) (measured in 10 specimens); ear length is 15 to 17 mm (0.59 to 0.67 in), averaging 16 mm (0.63 in) (measured in 7 specimens); and condylo-incisive length (a measure of total skull size) is 26.9 to 31.4 mm (1.06 to 1.24 in), averaging 29.6 mm (1.17 in) (measured in 5 specimens). …

As far as known, Oryzomys gorgasi has a disjunct distribution in northwestern South America, including Colombia, Venezuela, and Curaçao. In a 2009 paper, Carleton and Arroyo-Cabrales speculated that its distribution may extend into Central America. The Colombian population is known from the holotype only, caught at Loma Teguerre (7°54'N, 77°W) in Antioquia Department, northwestern Colombia, near the Río Atrato, at about 1 m above sea level. The location is apparently a freshwater swamp, and Hershkovitz suggested that O. gorgasi probably occurred throughout the swamp forests in the Río Atrato basin. On Curaçao, it is known from cave faunas at Tafelberg Santa Barbara, Noordkant, Ser'i Kura, and Hermanus. At Tafelberg Santa Barbara, it was found in association with introduced black rats (Rattus rattus), indicating that the population persisted at least until the first European contact in 1499. In Venezuela, it was found on El Caimito, a small (57 ha, 140 acres) islet just east of the outlet of Lake Maracaibo in the state of Zulia, where the only other native non-flying mammal is the opossum Marmosa robinsoni. El Caimito is separated from the mainland by a narrow, brackish channel and contains sand banks with xerophytic vegetation surrounded by marshy lagoons with Rhizospora mangle mangroves. …