GREY SHORT-TAILED OPOSSUM Monodelphis domestica FAUNA PARAGUAY

Monodelphis domestica (Wagner 1842) Image Gallery
TAX: Class Mammalia; Subclass Theria; Infraclass Metatheria; Order Didelphimorphia; Family Didelphidae; Subfamily Didelphinae (Myers et al 2006). Twenty-nine species are recognised in this genus, three are present in Paraguay. The scientific name Monodelphis is from the Greek meaning "single womb", domestica is Latin for "domestic" derived from the species habit of entering human dwellings. The species is monotypic. Wetzel & Lovett (1974) mistakenly regarded Didelphys brevicaudis as a senior synonym of this species. Synonyms adapted from Macrini (2004) and Gardner (2007):
Didelphys domestica JA Wagner 1842:359 Type Locality "Cuayaba", Mato Grosso, Brazil.
Hemiurus hunteri P.Gervais 1856:101. Name combination. Not Didelphys hunteri Waterhouse (1841).
Hemiurus concolor P.Gervais 1856:pl.16. New name combination.
[Didelphys (]Microdelphys[)] domestica Burmeister 1856:87. Name combination.
Didelphys [(Peramys)] domestica O.Thomas 1888:358. Name combination.
Hemiurus domesticus Winge 1893:55. Name combination.
P[eramys]. domesticus O.Thomas 1897:220. Name combination.
Peramys domestica Heck 1912:14 Name combination.
[Didelphis (]Monodelphis[)] concolor Matschie 1916:271. Name combination.
[Didelphis (]Monodelphis[)] domestica Matschie 1916:272. Name combination.
Monodelphis domestica Pohle 1927:240. First use of current name.
Monodelphis domestica domestica Cabrera 1958:8. Name combination.
Monodelphis brevicaudis brevicaudis Wetzel & Lovett 1974:206. Not Didelphys brevicaudis Olfers (1818).
Monodelphis domesticus Mello 1977:391 Name combination and incorrect gender.
ENG: Grey Short-tailed Opossum, Grey-faced Opossum (Macrini 2004), Short Bare-tailed Opossum (Macrini 2004)
ESP: Colicorto gris (Emmons 1999), Colicorto chaqueño (Massoia et al 2000), Catita (Massoia et al 2000).
GUA: Anguja mykure (Esquivel 2001), Mbicuré-í (Massoia et al 2000).
DES: Pelage short, dense and smooth, somewhat uniformly brownish-grey but paler and more creamy-white towards the cheeks and venter, often with a slight yellowish tinge. Some individuals may show indistinct olive-speckling to the dorsum and/or paler flanks. Pelage is fluorescent under ultra-violet light, that of study skins reddish-purple dorsally and reddish-orange ventrally. Naked nose pinkish, ears are large and greyish. Semi-prehensile tail short and thick-based, dark brown above and paler below and at the tip. It is furred at the basal 25% of its length and naked for the rest. Extremities pinkish. Females lack a pouch and usually possess 13 nipples, though in some the most anterior may be absent and they may have only 11 or 12. CR - Skull of adult males larger than that of females, but female skull bones grow faster because of a shorter growing period. Well-developed sagittal crest. Basal Length: 35.7mm; Premaxillary-Condylar Length: 38.7mm (26.7-44.7mm); Greatest Width: 19.8; Greatest Zygomatic Width: 20.8mm (14.3-25mm); Mandible Length: 28.8mm (19-34.4mm); Length of Nasals: 17.8mm; Maximum Nasal Width: 4.6mm; Minimum Nasal Width: 2.3mm; Inter-temporal Constriction: 6mm; Palate Length: 20.3mm; Palate Width Inside M3: 12.1mm: Palate Width Outside M3: 7.1mm; Length of Palatal Vacuities: 2.9mm; Basisphenoid + Basioccipital Length: 12.6mm. (Macrini 2004) DF: I5/4 C1/1 P 3/3 M 4/4 = 50. Molars are tribosphenic. Van Nievelt & Smith (2005) documented tooth eruption in this species as related to ageing, noting that whilst tooth emergence is subject to individual variation, the eruption of the upper molars is not. As a result they defined their class boundaries based on the eruption of the upper molars with the following results for live specimens: Dental Class 0 (0-31 days) no teeth emerged; Dental Class 1 (32-48 days) M1 erupts at approximately 35.8 days; Dental Class 2 (49-81 days); M2 erupts at 49 days; Dental Class 3a (82-107 days) M3 erupts at 83 days; Dental Class 3b (108-125 days) Sees the eruption of p3 (at 108 days) and P3 (at 111 days); Dental Class 4 (>125 days). These dental classes varied slightly for preserved or defleshed skulls Dental Class 0 (<46 days), Dental Class 1 (46-55 days), Dental Class 2 (56-97 days), Dental Class 3 (98-133 days) and Dental Class 4 (>133 days). Length M1-M3: 6.6mm. CN: 2n=18. X chromosome smaller than autosomes.
TRA: Well-developed curved claws and small digital pads (Macrini 2004).
MMT: Easily the largest of the Paraguayan Short-tailed Opossums. TL: 21.23cm (17.8-27cm); HB: 14.32cm (12.3-20cm); TA: 6.91cm (4.6-10.6cm) approximately 50% of body length; FT: 1.77cm (1.4-22cm); EA: 1.98cm (1.4-2.8cm); Distance from Muzzle to Eye 1.73cm; WT: 71.4g (36-93g) As much as 100-150g in captivity where males may be considerably heavier than females. Females stop growing upon reaching sexual maturity though males continue to grow and beyond Age class 5 are significantly larger and heavier than females (Bergallo & Cerquiera 1994). Growth in length is finite but mass increases through life. WN: 0.10g. (Massoia et al 2000, Macrini 2004, Eisenberg & Redford 1999, Emmons 1999)
SSP: Much the largest of the Paraguayan Short-tailed Opossums and with the most uniformly brownish-grey colouration. Monodelphis sorex is distinctly reddish in colouration, particularly on the head, rump and sides, which immediately separates it. On average it is almost twice the size of Monodelphis kunsi, with longer fur and proportionately longer ears. Cranially it has a much larger skull with a pronounced sagittal crest, the latter character absent in M.kunsi.
DIS: Widely distributed through the caatinga belt of Brazil south of the Amazon, into eastern Bolivia, across northern Paraguay and into the Chaco of northern Argentina where it is apparently restricted to Provincia Formosa. Flores (2006) maps the species for the Humid Chaco of Argentina but Chebez (2009) considers this an error.
HAB: Typical of xeric habitats, being found in the cerrado and Paraguayan Chaco where it inhabits cerradón, cerrado scrub and chaco woodland. Also in more open, grassy habitats, including recently-burned areas.
ALI: Carnivorous. A voracious hunter of invertebrates and small vertebrates including rodents, lizards, frogs and snakes, able to take prey of similar body mass to its own. They may take fruit and carrion when available. The sense of smell is used to detect food, the nose often being inserted into the substrate whilst sniffing. Prey is captured with the forefeet after a rapid pounce and vertebrates are killed with a bite to the back of the neck. Prey is often manipulated in the forefeet prior to consumption. The tail is carefully-removed from scorpions before they are eaten. There is no direct evidence proving that wild individuals require access to drinking water. Domestic individuals fed on commercially-available fox-food pellets performed better than those on a meat diet (Macrini 2004). Astúa de Morães et al. (2003) experimentally tested the proportions of protein, lipid, carbohydrate and fibre in the diet of adults (n=18) and juveniles (n=11) of this species under laboratory condtions. Mean proportions per 100g dry weight of food were: protein ad. 4.37g (+/-1.04), juv. 1.24g (+/-0.94); lipid ad. 0.88g (+/-0.51), juv. 0.15g (+/-0.11); carbohydrate ad. 2.03g (+/-1.31), juv. 1.91g (+/-1.62); fibre ad. 1.03% (+/-0.57), juv. 2.13% (+/-0.75). Santori et al (2004) described and illustrated the gut morphology of this species and associated it with dietary habits.
REP: Captive breeding studies of specimens collected in the Brazilian caatinga make this one of the most well-known small opossums. It breeds throughout the year in the Chaco and Brazilian caatinga producing at least two litters and occasionally as many six annually. Breeding is seasonal in Bahía, Brazil, and coincides with the wet season, with females becoming reproductively active once they reach Age Class 5. Initial interactions between male and female consist of genital sniffing and often followed by open-mouthed threat displays. Receptive females exhibit behaviours such as rump dragging, but even females exhibiting such behaviours respond aggressively to males and may continue to do so even whilst mating. Females do not have an oestral cycle and must be exposed to male pheromones to enter oestrus 4 to 11 days later. In the laboratory c86% of matings occurred in the dark phase of the laboratory-controlled mating cycle. Ovulation occurs 18-20 hours after mating, stimulated by contact with the male and conception 2 hours later. The gestation is 14 to 15 days, new-borns being c1cm long, altricial and immediately attaching to a nipple. Litters in wild populations in the Brazilian caatinga contain 6 to 11 offspring, with an average of 8.4. In captivity litters of 3 to 14 have been reported with an average of 7. The juveniles are attached to the nipple for 2 weeks before being transferred to the nest or carried on the mother´s back. Neonates that fall from the nipple are not retrieved by the mother, but older young which fall from her back are retrieved. Hair growth begins at 18-21 days and the eyes open at 28-35 days. Once hair has begun to grow the mother grooms her offspring using her tongue, teeth and forefeet. Wounds incurred prior to postnatal day 9 heal without scarring. Juveniles are capable of taking solid food at 4 to 5 weeks and captive juveniles can be successfully separated from the mother at 7 weeks. Typically weaning occurs at 8 weeks. The parent recognises her own young by their scent. A minimum of 7 to 8 weeks passes between litters. Sexual maturity is reached at 5 to 7 months, and captive individuals were able to reproduce at 15 months. Juvenile females do not reach puberty unless they are exposed to male pheromones. (Redford & Eisenberg 1999, Macrini 2004). Captive individuals breed happily in cages 43 x 22 x 13cm with a small nest box 18 x 13 x 10cm, a covering of wood-shavings on the floor and an ambient temperature of between 23.5 and 26.5ºC. Captive populations may produce up to four annual litters. Switching males following mating acts to reduce female violence and males must be removed upon birth of the litter. Upon reaching sexual maturity the siblings must be separated. Onset of reproductive declines begins earlier in females (18-24 months) than males (24-30 months). (Bergallo & Cerquiera 1994, Macrini 2004).
BEH: Activity Levels Terrestrial and solitary in habits. Though frequently described as diurnal in habits (Redford & Eisenberg 1999, Massoia et al 2000), Macrini (2004) states that the greatest period of activity is for the first 1 to 3 hours after dusk and that activity continues periodically through the night. A population peak is reached in July in Pernambuco, Brazil (Bergallo & Cerquiera 1994). Home Range Home range in the Brazilian caatinga was estimated at 1209m² (+/- 1050m²) for males and 1789m² (+/- 488m²) for females. Territories are marked by rubbing the chin, side of the head and then flanks against a substrate. Additionally males may rub the venter and drag the scrotum across the surface. In the wild scent-marking is used to mark "personal space" such as the area immediately around the nest entrance. Under laboratory conditions animals scent mark their cage shortly after introduction. Head marking is the most frequently used technique, whilst hip-marking is seen more often in females. Scent marking behaviour appears to be related to increased androgen levels and is first seen at 14 weeks. Roosts Nests are built by both sexes, but those built by females tend to be more solidly constructed. In Brazil nests were built in crevices in rocky outcrops made of leaves, bark, snake skins, grasses, plastic, paper and cloth. Material is collected using the mouth but manipulated between the forelegs, hindlegs and semi prehensile tail. In the nest the animal sleeps on its side, curling into a ball during colder weather. They leave the nest cautiously, sniffing the air and frequently pausing motionless when disturbed. Grooming Behaviour Following feeding the animal frequently grooms, sitting semi-erect and licking the soles of the forefeet before moving them in a circular motion over the head and snout. The chest and abdomen may then be licked and the incisors used as a sort of "comb". The hindfeet are used primarily for scratching with the animal leaning to one side and scratching the dorsum, back of the head, abdomen, shoulders and sides for a period of 2 to 10 seconds. After scratching the feet are licked. Periods of grooming may last 2 minutes or more. Nuzzling is a behaviour associated with odour uptake from dry surfaces. It involves the repeated rubbing and moistening of dry surfaces with the underside of the nose, followed by licking of the nose to promote oral uptake of odours. (Macrini 2004). Aggressive Behaviour This species is intolerant of conspecifics responding aggressively, growling and hissing and threatening with open mouth. Continued approach of an intruder incites the defensive animal to adopt a semi-erect posture, increasing to a near erect posture that precedes a strike with the forefeet and mouth if the threat persists. Aggressive encounters are rarely prolonged and though open-mouth threats are performed by both sexes, physical conflict occurs only between males. Males do not behave aggressively towards females, though females frequently do towards males. Juveniles may engage in play-fighting, though adults rarely or never do so. (Macrini 2004). Parasites For Brazil Limardi (2006) notes the following ectoparasites of this species: Siphanoptera Adoratopsylla antiquorum (Ctenophthalmidae). Acari: Metastigmata Ixodes amarali, Amblyomma sp., Ornithodoros talaje (Ixodidae). Acari: Mesostigmata Ornithonyssus bursa and O.lutzi, Lepronyssoides perierai (Macronyssidae); Eubrachylaelaps rotundus, Mysolaelaps heteronychus and M.parvispinosus, Gigantolaelaps butantanensis, G.oudemansi, G.goyanensis and G.vitzthumi, Laelaps castroi, L.lateventralis and L.paulistanensis (Laelapidae). Acari: Prostigmata Parasecia aitkeni and Trombewingi bakeri (Trombiculidae). Thatcher (2006) gives the following endoparasites from Brazil: Cestoda Linstowia schmidti (Anoplocephalidae). Longevity Captive individuals have a natural lifespan of 36 to 42 months, with one individual living 49 months. (Macrini 2004).
VOC: Aggressive interactions are accompanied by growls and hisses. Males may try to appease aggressive females with clicking vocalisations. (Macrini 2004).
HUM: This species occasionally enters human dwellings (hence the epithet domestica) where it may be confused with a mouse or rat. The species may have benefitted from deforestation opening up new areas of potential habitat and enabling them to colonise secondary habitats (Emmons 1999).
CON: Globally considered to be of Low Risk Least Concern by the IUCN, click here to see their latest assessment of the species. The species is apparently common in its Brazilian range and though little data is available for Paraguayan populations it is the most frequently encountered member of its genus and given the isolated nature of its preferred habitat it is not likely to be under any direct threat. Flores (2006) considers the species vulnerable in Argentina given its limited range, but Chebez (2009) notes that is locally common and occurs within the Reserva Natural de Formosa. Population densities in the caatinga of Brazil varied from 0 to 4/ha.
Citable Reference: Smith P (2008) FAUNA Paraguay Online Handbook of Paraguayan Fauna Mammal Species Account 10 Monodelphis domestica.
Last Updated: 1 July 2009.
References:
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ACKNOWLEDGEMENTS
Special thanks to Juan Carlos Chebez for providing important literature and Nilton Cáceres for very kindly reviewing texts and providing a copy of his book Os Marsupiais do Brasil.