647.

White-tipped Oldfield Mouse

Thomasomys caudivarius

French: Thomasomys a pointe blanche / German: \WeilRschwanz-Paramomaus / Spanish: Raton de erial de cola blanca

Other common names: \ White-tipped Thomasomys

Taxonomy. Thomasomys caudivarius Anthony, 1923, “Taraguacocha, Cordillera de Chilla, 10,750 feet [= 3277 m], Provincia del Oro, Ecuador.”

Morphological variation among populations of 1. caudivarius suggests that it might be polytypic. Monotypic.

Distribution. W Andes slope from C Ecuador to N Peru; records of NW Ecuador need to be confirmed.

Descriptive notes. Head—body 99-125 mm, tail 141-163 mm, ear 15-19 mm, hindfoot 28-31 mm. No specific data are available for body weight. Pelage of the White-tipped Oldfield Mouse is soft, fine, dense, and long, usually more than 10 mm in midline of back and toward tail. Dorsum is dark brown; venteris ash-gray to brown. Hairs on back and belly are bicolored, always with bases of gray to dark gray. Head is similar in color to back. Area between eyes and snout can be darker. Paws are moderately long and broad posterior, with silvery, brown, or blackish hair on its upper surface and with black soles. Small tufts of longer hairs, whitish orsilver, are usually present on claws. Fifth finger is semi-usable. Tail is unicolored or bicolored, thick, and long, reaching ¢.120% or more of head-body length; it is naked in appearance, finely scaly, and covered with small short and fine hair; and tip of the tail is white. Females have three pairs of nipples: one postaxial, one abdominal, and one inguinal.

Habitat. Along small mountain valley streams among thick shrubs and low stunted trees and in open paramo with abundant low shrubs and no treesat elevation of 2750— 3350 m.

Food and Feeding. The White-tipped Oldfield Mouse eats seeds and insects.

Breeding. No information.

Activity patterns. The White-tipped Oldfield Mouse is probably terrestrial and nocturnal.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Natural habitat in Cordillera de Chilla where type locality of the White-tipped Oldfield Mouse was collected has been heavily fragmented in recent decades. Forests and moors have been replaced by pastures and large extensions of pine plantations leaving only small isolated remnants on edges of ravines and rocky walls.

Bibliography. Anthony (1923), Brito & Garcia (2016), Brito & Valdivieso-Bermeo (2016), Cabrera (1961), Jarrin (2001), Luna & Pacheco (2002), Moreno & Albuja (2012), Musser & Carleton (2005), Pacheco (2003, 2015b, 2016c¢), Pozo et al. (2006), Tirira (1999).