Marmosa constantiae Thomas, 1904 Didelphidae Russell A. Mittermeier Don E. Wilson Thomas 1904 [1363,1767,1574,1616] Mammalia Didelphidae Marmosa Animalia Didelphimorphia 12 141 Chordata species constantiae    20.    White-bellied Woolly Mouse Opossum    French: Opossum de Constance/ German: \WeiRbauch-Zwergbeutelratte/ Spanish: Marmosa lanuda de vientre claro   Other common names: Bay-colored Mouse Opossum, Pale-bellied Woolly Mouse Opossum   Taxonomy. Marmosa constantiae Thomas, 1904,   “ Chapada,” Mato Grosso, Brazil.  This species has had subspecies proposed, but they are not included here. Monotypic.    Distribution.N & E Bolivia, SW Brazil (Rondonia, Mato Grosso, Mato Grosso do Sul), NW Argentina (Jujuy, Salta), and Paraguay.   Descriptive notes.Head-body 13-4— 18 cm, tail 18:6-22 cm; weight 63-90 g. Dorsal fur of the White-bellied Woolly Mouse Opossum is gray with a slight cast of brownish, yellowish, or medium brown that is brighter on sides of body and extends up to forehead. Yellow fur occurs between broad dark brown or black eye-rings that surround black eyes; rings do not extend to ears. Tail length is c¢.130% of head-body length, and tail has fur on proximal 2 cm. Naked part oftail is brown at base and white on distal one-half to one-third, with a clear division. Ventral furis pinkish to yellow or creamy white, extending from cheeks and chin to anus. Fur is long and woolly, except for rump, whereit is shorter. Ears are dark brown. Females lack a pouch and have 15 mammae, seven on each side, and a medial mamma. The White-bellied Woolly Mouse Opossum has a 2n = 14, FN = 20 karyotype, with acrocentric X-chromosome and Ychromosome. There is no sexual dimorphism in skull size and shape.   Habitat.Generally humid forests, but in drier biomes within its distribution, preferring subhumid or semi-humid forests.   Food and Feeding.One specimen of the White-bellied Woolly Mouse Opossum from Jujuy, Argentina had remains of Hemiptera insects and vegetable matter in its stomach. Otherwise, its feeding habits are unknown.   Breeding.In Bolivia, a female with five young was captured in August, a lactating female was caught in May, and non-reproductive females were collected in July-August. In Argentina, a lactating female was captured in June, and a juvenile was caught in August.   Activity patterns.There is no information available for this species.   Movements, Home range and Social organization.The White-bellied Woolly Mouse Opossum is arboreal. In south-western Brazil, it was captured only in understory traps but not on the ground.   Status and Conservation.Classified as Least Concern on The IUCN Red List. Whitebellied Woolly Mouse Opossums occurin several protected areas, and there is no reason to think that populations have decline rapidly enough to qualify for listing in a threatened category. It is still reasonably widely distributed, but it is dependent upon a highly fragile habitat in the fog belt in arid regions. Climatic and land-use changes could quickly result the White-bellied Woolly Mouse Opossum becoming seriously threatened.   Bibliography.Abdala et al. (2006), Anderson (1997), Astua (2010), Creighton & Gardner (2007b), Emmons & Feer (1997), Flores et al. (2000), Gardner (2005), Gardner & Creighton (2007b), Gutiérrez et al. (2010), Hannibal & Caceres (2010), Hershkovitz (1992a), Palma & Yates (1996), Redford & Eisenberg (1992), de la Sancha etal. (2012), Smith (2011), Voss et al. (2014). 3819445355 [2060,2509,1785,1810] Brazil Chapada 12 141 1 Mato Grosso