661.

Slender Oldfield Mouse

Thomasomys gracilis

French: Thomasomys gracile / German: Zierliche Paramomaus / Spanish: Raton de erial esbelto

Other common names: Gracile Thomasomys

Taxonomy. Thomasomys gracilis Thomas, 1917, “Matchu Picchu, 12,000 feet [= 3658 m],” Cusco, Peru.

Systematics of 1. gracilis relative to 1. cinnameus and 1. hudson: is unclear and requires additional taxonomic research. Monotypic.

Distribution. SE Peru (Cusco Region).

Descriptive notes. Head-body 83-101 mm, tail 120 mm, ear 15-18 mm, hindfoot 22-23 mm. No specific data are available for body weight. Dorsal fur of the Slender Oldfield Mouse is soft, dense, and comparatively long (average 11 mm). Dorsum is dark grayish buff or clay, with undefined dark region along midline over rump. Venteris soiled grayish buff, with hairs slaty basally and not sharply contrasting with dorsum. Ears are blackish and contrast with head color. Mystacial vibrissae are moderately long, extending backward slightly beyond pinnae when bent. Tail is 119-142% of head-body length, poorly bicolored but overall blackish brown and uniform, with tip sometimes white. Hindfoot has dark brown metatarsal patch, with edges and digits lighter. No gap occurs between thenar and hypothenar pads. Hallux is long.

Habitat. Montane forests with wet bunch grass on gently sloping ground or steep slopes dominated by melastome ( Melastomataceae) shrubs and ferns and elfin forest patches of bamboo thickets and large mossand epiphyte-covered trees at elevations of 277-4270 m.

Food and Feeding. No information.

Breeding. In May during the rainy season, two male Slender Oldfield Mice had scrotal testes; two others had very small, nonscrotal testes (3 mm); and two females has finished lactating.

Activity patterns. No information.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Near Threatened on The IUCN Red List.

Bibliography. Eisenberg & Redford (1999), Pacheco & Vargas (2008a).