Cricetidae Author Don E. Wilson Author Russell A. Mittermeier Author Thomas E. Lacher, Jr text 2017 2017-11-30 Lynx Edicions Barcelona Handbook of the Mammals of the World – Volume 7 Rodents II 204 535 book chapter 80832 10.5281/zenodo.6707142 ab66b2b7-9544-4411-bf61-5bc3651d7bca 978-84-16728-04-6 6707142 710. Crafty Vesper Mouse Calomys callidus French: Calomys rusé / German: Geschickte Vespermaus / Spanish: Ratén laucha astuto Other common names: Crafty Laucha , Reclusive Laucha Taxonomy. Hesperomys venustus callidus Thomas, 1916 , Goya, 600 ft (= 183 m ), Corrientes , Argentina . This species is monotypic. Distribution. W Brazil (Rondoénia, Mato Grosso, and Mato Grosso do Sul states), C Paraguay, and along Parana River in NE Argentina . Descriptive notes. Head-body 79-134 mm, tail 50-87 mm, ear 14-18 mm, hindfoot 16-23 mm; weight 21-51 g. The Crafty Vesper Mouse is a large species of Calomys ;, pelage is short and appressed; dorsum is grayish, buffy wash on flanks and venteris pale gray (hairsslaty basally, white or grayish terminally). Ears are large, with brown inner and black outer surfaces; inconspicuous post-auricular patch is present. Tail is shorter than head-body length, thinly haired, bicolored (pale brownish above and grayish white on sides and below), and without tuft of hair at tip. There are ususally ten mammae. Habitat. Grasslands and grassland/monte ecotone and other riparian forests of the Mesopotamian alluvial system of Argentina , enclaves of grassy vegetation and old fields in western Brazil, and likely similar habitats in Paraguay. Food and Feeding. No information. Breeding. No information. Activity patterns. The Crafty Vesper Mouse is terrestrial and nocturnal. Movements, Home range and Social organization. The Crafty Vesper Mouse is considerable rarer than other species in the habitats where it is found. Status and Conservation. Classified as Least Concern on The IUCN Red List. Bibliography. Bonvicino et al. (2010), Cassola (2016w), Contreras et al. (2003), Corti et al. (1987), Douglass & Vadell (2016), Hodara et al. (1994), Maroli et al. (2015), Mattevi et al. (2005), Percich & Hodara (1990), Roldan et al. (1985), da Rosa et al. (2012), Salazar-Bravo (2015c), Vadell & Gémez (2016), Vadell, Bellomo et al. (2011), Vadell, Garcia & Gémez (2017), Vitullo, Espinosa & Merani (1990), Vitullo, Kajon et al. (1985).