Thylamys macrurus (Olfers, 1818)

Russell A. Mittermeier & Don E. Wilson, 2015, Didelphidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 129-186 : 178

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Thylamys macrurus


85. View Plate 9: Didelphidae

Paraguayan Fat-tailed Opossum

Thylamys macrurus

French: Opossum a longue queue / German: Paraguay-Fettschwanzbeutelratte / Spanish: Marmosa coligruesa de Paraguay

Other common names: Long-tailed Fat-tailed Opossum, Paraguayan Fat-tailed Mouse Opossum, Paraguayan Thylamys

Taxonomy. Didelphys macrura Olfers, 1818 ,

“Stidamerica.” Restricted by R.S. Voss and colleagues in 2009 to “ Twenty-eight kilometers SW Pedro Juan Caballero , Departamento Anambay, Paraguay.”

This species is monotypic.

Distribution. S Brazil (Mato Grosso do Sul) and E Paraguay. View Figure

Descriptive notes. Head-body 10.1-13.5 cm, tail 13.2-15.4 cm; weight 30-57 g. The Paraguayan Fat-tailed Opossum is the largest species in the genus. Its dorsal fur is grayish overall, with conspicuous tricolored pattern. Mid-dorsal fur is dark grayish or grayish-brown, with four-color banded cover hairs that are gray at bases, then dark brown, then creamy, and dark at tips. Guard hairs are longer, and gray-based with dark or white tips. Fur on body sides 1s pale gray, similar to mid-dorsal fur but paler. Head is the same color as middorsal fur; mid-rostral fur is pale gray, with a distinct gray line of tricolored, gray-based white hairs with black tips. There is white-based dark-tipped fur in front of ears and above eyes, and there are dark, narrow eye-rings that extend slightly toward nose but not toward ears. Tail length is c.120% of head-body length, and tail is basally furred for 10 mm, bicolored proximally (grayish dorsally and whitish ventrally), and entirely white on distal one-third to one-fifth. Tail can store fat (become incrassated), although tail fat is much less apparent on the Paraguayan Fat-tailed Opossum than in other species of Thylamys . Ventral fur is creamy white from chin to anus, with narrow (less than 3 mm) lateral bands of gray-based hairs. Throat gland is present in both sexes. Fur is dense, short (5-6 mm) ventrally and longer (9-10 mm) dorsally, with even longer (11-12 mm) guard hairs. Feet are large and whitish, limbs are grayish dorsally (paler on forelimbs than hindlimbs) and creamy-white ventrally, and ears are large, uniformly dark-brownish, and naked. Females lack a pouch, but number of mammae is unknown. The Paraguayan Fat-tailed Opossum has a 2n = 14, FN = 20 karyotype, with four pairs of biarmed and two pairs of acrocentric autosomes, and with an acrocentric X-chromosome. The Y-chromosome is absent or unknown.

Habitat. Tall subtropical humid (semi-evergreen) forests in Paraguay and arboreal dense savannas (cerrado sensu stricto) and deciduous and semi-deciduous forests associated with cerrado formations in western Brazil. The Paraguayan Fat-tailed Opossum seems to be quite a generalist relative to its habitat use.

Food and Feeding. There is no information available for this species.

Breeding. Reproductive patterns of the Paraguayan Fat-tailed Opossum can only be inferred from capture frequencies of individuals in different age classes. In western Brazil, the majority ofjuveniles were captured during the rainy season in November— February, with a single capture of ajuvenile during the dry season in July, which strongly suggested a breeding season associated with the wet season when young are born, weaned, and start to disperse. This was also supported by higher frequency of heavier individuals captured in the dry season.

Activity patterns. There is no specific information available for this species, but the Paraguayan Fat-tailed Opossum is probably nocturnal.

Movements, Home range and Social organization. In western Brazil, the Paraguayan Fat-tailed Opossum is captured on the ground, or when it is caught in understory traps, there is no difference in use of understory or ground levels. Escape behaviors, however, were more frequent on the ground.

Status and Conservation. Classified as Near Threatened on The IUCN Red List. The Paraguayan Fat-tailed Opossum nearly qualifies as Threatened based on inferred population decline due to habitat conversion to agriculture and from logging. In Paraguay, the Paraguayan Fat-tailed Opossum is only known from a few specimens.

Bibliography. de Andreazzi et al. (2011), Braun etal. (2005), Caceres, Bornschein et al. (2007), Caceres, Napoli, Casella & Hannibal (2010), Caceres, Napoli & Hannibal (2011), Caceres, Napoli, Lopes et al. (2007), Carmignotto & Monfort (2006), Creighton & Gardner (2007c), Giarla et al. (2010), Hannibal & Caceres (2010), Melo & Sponchiado (2012), Palma, A.R.T. & Vieira (2012), Palma, R.E. (1995), Palma, R.E., Boric-Bargetto et al. (2014), Palma, R.E., Rivera-Milla et al. (2002), Smith (2009c), Solari (2003), Svartman (2009), Voss, Myers et al. (2009).














Thylamys macrurus

Russell A. Mittermeier & Don E. Wilson 2015

Didelphys macrura

Olfers 1818