491.

Nicaraguan Marsh Rice Rat

Oryzomys dimidiatus

French: Oryzomys du Nicaragua / German: Nicaragua-Sumpfreisratte / Spanish: Rata arrocera de marisma de Nicaragua

Other common names: Nicaraguan Oryzomys, Nicaraguan Rice Rat, Thomas's Rice Rat

Taxonomy. Nectomys dimidiatus Thomas, 1905, “Escondido River, 7 miles [= 11 km] below Rama [South Caribbean Coast Autonomous Region (previously part of Zelaya Department) |, Nicaragua.” This species is monotypic.

Distribution. Known only from two sites at and near type locality in SE Nicaragua.

Descriptive notes. Head-body 118-125 mm, tail 110-115 mm, ear 13-15 mm, hindfoot 26-28 mm; weight 46 g. The Nicaraguan Marsh Rice Rat is medium-sized, with gray-brown back, grizzled with black grading to buffy brown on sides; underparts are silvery gray and not strongly demarcated from upperparts. Fur is slightly glossy; ears are short, well-haired, and partially concealed in fur; snout is relatively short; tail is very faintly bicolored and slightly shorter than head-body length; feet are brownish above; and hindfeet have short fringes of stiff hairs on sides and no ungual tuft at bases of claws. It is said to resemble Coues’s Marsh Rice Rat ( O. couesi) but differs from it most conspicuously in smaller external and cranial size, less robust dentition, darker (more black evident) dorsal color, grayish as opposed to bufty venter, and proportionally shorter tail, clearly shorter than head-body length. Karyotype is unknown.

Habitat. Known from only two specimens: one from banana plantation on very wet, red clay and one from a stand of dense cane, 2-4-3 m tall, adjoining a river.

Food and Feeding. No information.

Breeding. No information.

Activity patterns. The Nicaraguan Marsh Rice Rat is probably semi-aquatic.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Nevertheless, the Nicaraguan Marsh Rice Rat apparently has a very small distribution, and lack of any details about local population numbers or even minimal aspects of habitat requirements challenge conservation assessment.

Bibliography. Genoways & Jones (1971), Hershkovitz (1948, 1970), Reid (2009), Thomas (1905), Timm & Reid (2008).