Lestodelphys halli (Thomas, 1921)

Astúa, D., 2015, Didelphidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 129-186 : 175

76.

Patagonian Opossum

Lestodelphys halli

French: Opossum de Patagonie / German: Patagonien-Beutelratte / Spanish: Zariglieya patagonica

Taxonomy. Notodelphys halli Thomas, 1921 ,

Argentina, Santa Cruz, “ Cape Tres Puntas, S.E. Patagonia, 47°S.” Emended by O. Thomas in 1929 to “Estancia Madujada, not far from Puerto Deseado,” Santa Cruz, Argentina.

This species in monotypic.

Distribution. C & S Argentina, from Mendoza S to Santa Cruz.

Descriptive notes. Head-body 12.3-14.4 cm, tail 7.4-9.9 cm; weight 60-100 g.

Dorsal fur on the Patagonian Opossum is dark gray, and body sides are distinctly pale gray, resulting in tricolored fur pattern (dorsum, body sides, and ventral surface with clearly different colors). Top of head is gray, like dorsum, and darker fur extends onto creamy mid-rostral fur as a narrow stripe almost reaching nose. Black eye-rings do not reach bases of ears and are surrounded by creamy fur on cheeks and forehead. Tail length is ¢.65% of head-body length, and tail has fur on proximal 20 mm. Naked rest of tail is dark grayish-brown dorsally and whitish ventrally and at tip. Tail can store fat and become strongly incrassated; it can increase quickly in thickness. Ventral fur is white from chin to anus, and throat gland is present. Furis short, dense, fine, and soft. Forelimbs, forefeet, ankles, and hindfeet are pure white, and ears are short, rounded, and pinkish, with a creamy patch at their posterior bases. Females lack a pouch, and 17-19 mammae are present, with eight or nine on each side and a medial mamma. The Patagonian Opossum has a 2n = 14, FN = 24 karyotype, with a small biarmed Xchromosome and a very acrocentric Y-chromosome.

Habitat. Semi-desert shrublands and steppe habitats in the Patagonian and Monte Desert phytogeographic provinces. Captures of Patagonian Opossums are often associated with water and shrubby gallery vegetation.

Food and Feeding. Most diet information of the Patagonian Opossum comes from anecdotal reports. Observations of captive individuals suggest a clear preference for an animal diet, particularly a preference for vertebrate meat. Captive specimens usually preferred raw meat over arthropods, and all proved to be efficient predators. They successfully attacked,killed, and ate offered rodents (Olive-colored Akodont, Abrothrix olivaceus, and Eastern Patagonian Laucha, Eligmodontia typus), some weighing one-half their size. These were captured with the mouth and forelimbs, killed with a quick and precise bite on the neck, and consumed headfirst. Despite the apparent preference of captive Patagonian Opossums for vertebrates, beetles have been recorded in stomachs of wild-caught individuals. A recent detailed study of its diet in southern Patagonia confirmed that it is mostly “faunivorous,” but it feeds mainly on invertebrates, with 87% of analyzed samples including arthropods, followed by vertebrates (10%) and a small amount of fruits (2%). Arthropods consumed included Coleoptera, Orthoptera, Lepidoptera, scorpions, spiders, and solifuges. Vertebrates included lizards (Liolaemus) and passerine birds. Patagonian Opossums are able to store fat in theirtails, and captive individuals given enough food increased their tail thickness on a daily basis, sometimes reaching a diameter of 25 mm. They are also able to enter torpor when deprived of food.

Breeding. Captive Patagonian Opossums built nests with grasses, but these nests were unrelated to breeding activity. Other than the fact that they possess 17-19 mammae, details about breeding are unknown.

Activity patterns. There are no precise details on activity patterns of Patagonian Opossums in the wild, but captive individuals were both diurnal and nocturnal. Nocturnal activities were more frequent, with a peak after sunset and another before sunrise.

Movements, Home range and Social organization. The Patagonian Opossum is considered primarily terrestrial because it is always captured in traps set at ground level, or even in traps set in burrows of tuco-tucos (Ctenomys). It could even be considered semi-fossorial because captive specimens were seen digging, especially in sandy substrate. They dig with their forefeet, used alternatively, and they throw dug material back between their hindlimbs, which are held firmly on the ground and wide apart. Captive individuals were seen making subterranean galleries, about the same diameteras their bodies, with a terminal chamber used as a day resting site. Patagonian Opossums can climb well; captive specimens are able to climb using their forefeet, hindfeet, and tail. Tail was previously considered to lack prehensile ability, but it has a prehensile tip capable of supporting weight of an individual for a few seconds. The Patagonian Opossum also jumpseasily vertically and diagonally, being able to cover ¢.30 cm in a single jump.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Patagonian Opossum has a wide distribution, presumably a large overall population, and occurs in several protected areas. There are no major conservation threats to the Patagonian Opossum, although some populations are threatened by habitat modification by humans.

Bibliography. Birney, Monjeau et al. (1996), Birney, Sikes et al. (1996), Formoso et al. (2011), Gardner (2005), Geiser & Martin (2013), Mares & Braun (2000), Marshall (1977), Martin, G.M. (2005), Martin, G.M. & Sauthier (2011), Martin, G.M. et al. (2008), Pardinas et al. (2008), Pearson (2007), Redford & Eisenberg (1992), Sauthier et al. (2007), Thomas (1929), Voss & Jansa (2009), Zapata et al. (2013).

Figures

76. Patagonian Opossum (Lestodelphys halli), 77. Karimi’s Fat-tailed Opossum (Thylamys karimii), 78. Dwarf Fat-tailed Opossum (Thylamys velutinus), 79. Elegant Fat-tailed Opossum (Thylamys elegans), 80. Pallid Fat-tailed Opossum (Thylamys pallidior), 81. Tate's Fat-tailed Opossum (Thylamys tatei), 82. Mesopotamian Fat-tailed Opossum (Thylamys citellus), 83. Dry Chaco Fat-tailed Opossum (Thylamys pulchellus), 84. Chacoan Fat-tailed Opossum (Thylamys pusillus), 85. Paraguayan Fat-tailed Opossum (Thylamys macrurus), 86. Argentine Fat-tailed Opossum (Thylamys sponsorius), 87. Buff-bellied Fat-tailed Opossum (Thylamys venustus), 88. Bishop's Slender Opossum (Marmosops bishop), 89. Junin Slender Opossum (Marmosops juninensis), 90. Delicate Slender Opossum (Marmosops parvidens), 91. Pantepui Slender Opossum (Marmosops pakaraimae), 92. Pinheiro’s Slender Opossum (Marmosops pinheiroi), 93. Handley’s Slender Opossum (Marmosops handleyi), 94. Gray Slender Opossum (Marmosops incanus), 95. Brazilian Slender Opossum (Marmosops paulensis), 96. Neblina Slender Opossum (Marmosops neblina), 97. Tschudi’s Slender Opossum (Marmosops impavidus), 98. Spectacled Slender Opossum (Marmosops ocellatus), 99. Creighton’s Slender Opossum (Marmosops creightoni), 100. White-bellied Slender Opossum (Marmosops noctivagus), 101. Narrow-headed Slender Opossum (Marmosops cracens), 102. Dusky Slender Opossum (Marmosops fuscatus), 103. Panama Slender Opossum (Marmosops invictus)

Distribution. C & S Argentina, from Mendoza S to Santa Cruz.