705.

Delicate Vesper Mouse

Calomys tener

French: Calomys délicat / German: Zierliche Vespermaus / Spanish: Raton laucha delicado

Other common names: Delicate Laucha

Taxonomy. Hesperomys tener Winge, 1887, Lagoa Santa, Rio das Velhas, Minas Gerais, Brazil.

This species is monotypic.

Distribution. C, SE & S Brazil, E Bolivia, E Paraguay, and NE Argentina .

Descriptive notes. Head-body 70-84.7 mm, tail 47-73-9 mm, ear 13-15-4 mm, hindfoot 15-5-17-7 mm; weight 12-1-16-9 g. The Delicate Vesper Mouse 1s moderately sized; tail is moderately long but not as long as head-body length; dorsum is often dark reddish, with hairs gray at bases; venter is pale to dark gray; skull is moderately sized, with greatest length of skull of adults 21-24-5 mm; supraorbital region is distinctly ledged and divergent posteriorly; alisphenoid strut is generally present; and maxillary toothrow is generally 3.2-3-6 mm.

Habitat. Open savannas with or without scrubs, gallery forest, “cerradao” (closed canopy dry wooded savanna), semideciduousforest, and altered vegetation of the Atlantic Forest bordering cerrado habitats.

Food and Feeding. The Delicate Vesper Mouse is reportedly herbivorous-omnivorous, with diets rich in plant material and fruits.

Breeding. Litters of the Delicate Vesper Mouse average 3-6 young; interval between reproductive bouts is c¢.22 days. Lactating females were found in November and pregnant females (with four embryos each) in November and February. Puberty was reached, on average, at 25 days old for males and 36 days for females.

Activity patterns. The Delicate Vesper Mouse is terrestrial, nocturnal, and crepuscular.

Movements, Home range and Social organization. The Delicate Vesper Mouse is more abundant in areas with high secondary strata (woody vegetation) than in grasslands. Average home range for adult males was 0-32 ha and slightly smaller for adult females at 0-24 ha. Average distance traveled per day was c.50 m. It reportedly decreases its activity on nights with full moon and prefers habitats with more dense vegetation cover in areas with abundant aerial predators.

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

Bibliography. Alho et al. (1986), Araripe et al. (2006), Bonvicino & Almeida (2000), Bonvicino, Lima & Almeida (2003), Bonvicino, Oliveira & DAndrea (2008), Briani et al. (2004), Bueno & Motta-Junior (2015), Caceres, Casella et al. (2008), Carmignotto, Bezerra & Rodrigues (2014), Carmignotto, de Vivo & Langguth (2012), Gettinger (1992), Goncalves et al. (2016), Henriques et al. (2006), Jorge et al. (2001), Leite & Patterson (2016a), Mares et al. (1986), Ribeiro & Marinho-Filho (2005), Rocha, C.R., Ribeiro & Marinho-Filho (2016), Rocha, C.R., Ribeiro, Takahashi & Marinho-Filho (2011), Salazar-Bravo (2015¢), de la Sancha (2014), Santos & Henriques (2010), Vieira (1999), Vieira & Baumgarten (1995).