500.

Alfaro’s Water Rat

Sigmodontomys alfari

French: Mélanomys d’Alfaro / German: Alfaro-Wasserratte / Spanish: Rata de agua de Alfaro

Other common names: Alfaro’s Rice Water Rat, Short-tailed Sigmnodontomys

Taxonomy. Sigmodontomys alfari J. A. Allen, 1897, “Jimenez (altitude, 700 feet [= 213 m]), Costa Rica.”

Sigmodontomys alfari is the type species of the genus. Apparently Sigmodontomys is nested within Melanomys in molecular based phylogenies but retained here as a full genus based on morphological grounds. Monotypic.

Distribution. Extreme E Honduras, Nicaragua, Costa Rica, Panama, W & C Colombia, NW Venezuela, and W Ecuador.

Descriptive notes. Head—body 120-172 mm, tail 149-190 mm, ear 19 mm, hindfoot 34-37 mm. No specific data are available for body weight. Alfaro’s Water Ratis a medium-sized oryzomyine, with tail longer than head-body length and hindfeet long and robust. Pelage is long, dense, and glossy; dorsally it ranges from dark ocherous orange to grizzled yellowish brown; and venter is gray, white, or ocherous. Ears are small, slightly hairy, and dark, contrasting with paler dorsal color. Manus and pes are covered dorsally with short, dark hairs. Small webs of skin are present between second, third, and fourth digits; hindfeet lack natatory fringes. Tail is unicolored and sparsely haired, without terminal tuft. There are four pairs of mammae. Chromosomal complement is 2n = 56, FN = b4.

Habitat. [Lowland forest typically from sea level to elevations of ¢.1300 m. Alfaro’s Water Rat also occurs in marshes, diverse plantations, and forest clearings.

Food and Feeding. No information.

Breeding. No information.

Activity patterns. Alfaro’s Water Rat is reportedly semi-aquatic, but there are no specific data on this topic. Individuals have been trapped on the ground.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as [Least Concern on The IUCN Red List.

Bibliography. Anderson, Tirira et al. (2016), Goodwin (1946), Handley (1966, 1976), Hanson & Bradley (2008), Hershkovitz (1944), Lord (1999), McCain et al. (2007), McPherson (1985), Musser, Carleton et al. (1998), Pine et al. (2012), Reid (2009), Weksler (2015b).