Recent phylogenetic studies have indicated that T. canescens is genetically distinct from other Marmosa species and therefore should be placed into a new genus, Tlacuatzin. They were previously recognized as Marmosa canescens.
Communication between T. canescens individuals of the same sex is almost always agonistic and they often times hiss at one another (Eisenberg, 1989). Males attempt to attract females through the use of clicking sounds (Eisenberg, 1989). Before copulation, males and females communicate through the exchange of loud noises, which lasts for approximately three minutes (Zarza, Ceballos and Steele, 2003).
Communication Channels: visual ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
According to the IUCN Red List, there is not enough data available for T. canescens to determine its conservation status. Some researchers have remarked that T. canescens is quite common and is in no danger of becoming extinct. However, there is an island population off the coast of Mexico where the introduction of a new species (Rattus rattus) has negatively impacted the size of the T. canescens population (Zarza, Ceballos and Steele).
Deforestation is a problem for many neotropical species (Sanchez-Cordero et al., 2005). The general consensus, however, is that T. canescens is not immediately threatened by people or deforestation due to its small size and nocturnal behavior (Nowak, 1991).
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
It is unlikely that T. canescens has a negative impact on humans.
There is little information about the positive economic influence Tlacuatzin canescens has on humans.
Tlacuatzin canescens individuals are hosts for the chigger species Eutrombicula batatas. No other parasites have been recorded for this species. Tlacuatzin canescens is a prey item for cougars and barn owls. Geckos are occasionally eaten by T. canescens, which may affect their populations.
Tlacuatzin canescens lives sympatrically with various other small mammals, including Baiomys taylori, Hodomys alleni, Neotoma mexicana, Oryzomys palustris and Megasorex gigas. Since T. canescens regularly eats fruits such as coconut, figs, bananas and oranges, it is likely that they act as seed dispersers.
Ecosystem Impact: disperses seeds
Commensal/Parasitic Species:
Tlacuatzin canescens is omnivorous (Zarza, Ceballos and Steele, 2003). Members of this species feed primarily on insects. Specifically, T. canescens eat praying mantises, cerambycid beetles and scarabiid beetles (Zarza, Ceballos and Steele, 2003). This species also preys upon geckos, bird eggs, bird nestlings and fledglings, coconut, banana, small rodents and figs (Nowak, 1991; Zarza, Ceballos and Steele, 2003).
Animal Foods: birds; mammals; reptiles; eggs; insects; terrestrial non-insect arthropods
Plant Foods: fruit
Primary Diet: omnivore
Tlacuatzin canescens is found in the neotropical region. Grayish mouse opossums are endemic to Mexico (Zarza, Ceballos and Steele, 2003). They are found along the western and southern coasts of Mexico, from the Baja peninsula to the Yucatan peninsula (Nowak, 1991; Zarza, Ceballos and Steele, 2003). Isolated populations occur on the Tres Marias Islands off of the Nayarit coast (Zarza, Ceballos and Steele, 2003). Some evidence suggests that this species also occurs in Guatemala; however it has not yet been confirmed there (Voss and Jansa, 2003).
Biogeographic Regions: neotropical (Native )
Grayish mouse opossums generally live in semi-deciduous and tropical forests that exhibit distinct wet and dry seasons (Zarza, Ceballos and Steele, 2003). However, they are also found in other habitats, including scrublands, grasslands, evergreen forests, orchards, fields and secondary-growth forests (Zarza, Ceballos and Steele, 2003). Tlacuatzin canescens is most often found at elevations below 1,000 m; but have been observed up to 2,100 m (Zarza, Ceballos and Steele, 2003).
Grayish mouse opossums live in nests near logs, rocks, tree hollows, cacti, and shrubs (Zarza, Ceballos and Steele, 2003). One study found that nearly all specimens of T. canescens in Sinaloa, Mexico lived in hollow areas of dead cacti (Nowak, 1991). Nests are typically made up of dry leaves, small stems and the plant fibers of Ceiba pentandra. Additionally, some individuals have been found living in the abandoned nests of birds, including Uropsila leucogastra and Thryothorus pleurostictus (Zarza, Ceballos and Steele, 2003).
Range elevation: 0 to 2100 m.
Average elevation: 1000 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; rainforest ; scrub forest
There is little information regarding the lifespan of T. canescens. In related species belonging to the genus Marmosa, such as Marmosa robinsoni, life expectancy is typically under 1 year of age in the wild and up to 3 years in captivity (Nowak, 1991).
Range lifespan
Status: captivity: 3 (high) years.
Typical lifespan
Status: wild: 1 (high) years.
Average lifespan
Status: wild: <1 years.
Tlacuatzin canescens individuals exhibit considerable variation. In particular, the population found in the Yucatan peninsula is distinct from populations in western Mexico (Voss and Jansa, 2003).
In general, this species has brownish to light gray fur on its upper parts and creamy to white fur on its legs (Zarza, Ceballos and Steele, 2003). The venter is yellow-cream in color. Eyes are surrounded by black rings, and the ears are rounded, broad, and lack hair. The fur varies from soft and short to coarse and long (Zarza, Ceballos and Steele, 2003. The tail is prehensile and partly covered in fur (sometimes with a white tip). The tail is about the same length as the body. The hind feet are naked from the toes to the heel and the fourth digit is longer than the others. In mature females, an orange-yellow patch of fur surrounds the inguinal mammae (Zarza, Ceballos and Steele, 2003). Except for this feature, males and females look almost identical. Tlacuatzin canescens is very small, the smallest opossum found in Mexico (Zarza, Ceballos and Steele, 2003).
The skulls of T. canescens have strongly developed zygomatic arches and post-orbital processes, and the skull is broad and short (Zarza, Ceballos and Steele, 2003). The dental formula is 5/4, 1/1, 3/3 and 4/4 (Eisenberg, 1989).
Range length: 205 to 350 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; sexes colored or patterned differently
Known predators for Tlacuatzin canescens include pumas, and barn owls (Zarza, Ceballos and Steele, 2003). There is little information on anti-predator adaptations of T. canescens. Their cryptic coloration and nocturnal habits may be their primary defenses.
Known Predators:
Anti-predator Adaptations: cryptic
Grayish mouse opossums are solitary mammals and reproduction is promiscuous. Males attract females by emitting clicking sounds (Eisenberg, 1989). During copulation, the male and the female suspend themselves upside down with the use of their prehensile tails (Zarza, Ceballos and Steele, 2003). Throughout copulation, the male grasps the female's neck with his mouth (Zarza, Ceballos and Steele, 2003). Once copulation is over, the male is rejected by the female and both leave the area (Zarza, Ceballos and Steele, 2003).
Mating System: polygynandrous (promiscuous)
Tlacuatzin canescens reproduces year round (Ceballos, 1990). However, females are most often found with young from July to September (Zarza, Ceballos and Steele, 2003). Litter size ranges from 8 to 14 and the average number of young is 11 (Zarza, Ceballos and Steele, 2003). Juveniles leave their mothers once they reach a mass of around 20 grams. Unlike many other marsupials, T. canescens females do not possess a pouch. Instead, they have a layer of hair found on their ventral side in which newborns finish developing (Zarza, Ceballos and Steele, 2003).
There is little information regarding gestation for T. canescens. In M. robinsoni, a closely related species, gestation is typically 14 days. Females of this species reach sexual maturity when they are approximately 6 months old.
Breeding interval: Breeding may occur more than once yearly, but little definitive information is available.
Breeding season: Mating occurs throughout the year but is concentrated in early summer.
Range number of offspring: 8 to 14.
Average gestation period: 14 days.
Average age at sexual or reproductive maturity (female): 6 months.
Average age at sexual or reproductive maturity (male): 6 months.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
There is little information regarding parental investment in T. canescens. However, similar to other marsupials, young are born very underdeveloped and must stay close to their mother in order to develop fully (Eisenberg, 1989).
In a closely related species, Marmosa robinsoni, weaning does not take place until the young are 60-70 days old (Nowak, 1991). Also, young stay attached to the teat for up to 30 days (Eisenberg, 1989).
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
The grayish mouse opossum (Tlacuatzin canescens) is a species of opossum endemic to Mexico. It is the sole species in the genus Tlacuatzin.
The grayish mouse opossum is an unusually small opossum, measuring 20 to 35 cm (7.9 to 13.8 in) in total length, including an 11- to 16-cm (4.3- to 6.3-in) tail. Adults weigh from 38 to 60 g (1.3 to 2.1 oz). The body is covered in short, soft fur, with a slightly woolly texture. As the common name suggests, the fur is pale to brownish grey in colour, fading to white or near-white on the under parts and legs. In addition, clearly visible rings of black hair occur around the eyes, and, on females, patches of orange fur in the groin region, sometimes extending to the thighs and up the midline almost to the throat.[2]
The whiskers are relatively short, and the ears are rounded, hairless, and dark in colour. The tail is long and prehensile, and hairless for almost all of its length, apart from the base. Females have nine teats, but, unlike many other marsupials, do not have a pouch.[2]
It is endemic to Mexico from southern Sonora to Oaxaca, with populations also on the Islas Marías and in the central Yucatán Peninsula.[1] It occupies seasonally arid habitats, especially mixed deciduous forests, but also scrub, grassland, and agricultural land. It has been reported up to elevations of 2,100 m (6,900 ft), although it is more commonly found below 1,000 m (3,300 ft).[2] Two subspecies are currently recognised:[3]
The main risks that threaten the Grayish mouse opossum is deforestation and competition with introduced species such as the Rattus rattus, known more commonly as the Black rat.[4]
The grayish mouse opossum is solitary and semiarboreal, being more terrestrial in its habits than other mouse opossums.[1] They have been reported to travel no more than 72 m (236 ft) between feeding sites, suggesting a small home range.[2] Population densities have been reported to range from 0.4 to 4.5 per hectare (0.16 to 1.82/acre).[5] The species has an omnivorous diet, but feeds mainly on insects such as bugs, cockroaches, moths, and beetles. It occasionally feeds on small lizards and bird eggs, and also feeds on fruit such as figs, coconuts, and oranges. Predators include barn owls and pumas.[2][6]
A nocturnal animal, the grayish mouse opossum spends the day in nests, generally in forks or hollows of trees, bushes or cacti, or in rock crevices. The nests are globular, constructed of leaves and stems, and lined with grass or plant fibres, such as the "cotton" obtained from kapok trees.[2] It may also use the abandoned hanging nests of orioles or wrens.[1]
Breeding occurs in late summer and early autumn.[1] The animals mate while hanging upside down from their tails, with the male tightly holding onto the female's neck with its jaws. The litter size ranges from 8 to 14.[5] The young attach themselves to teats shortly after birth, and are sheltered by a pouch-like layer of hair, in the absence of a true pouch. The young leave the nest once they reach about 20 g (0.7 oz) in weight.[2]
Not many parasites have been recorded from the grayish mouse opossum. The pinworm Tlacuatzoxyuris simpsoni (Nematoda, Oxyuridae), a parasite of the cecum, has been described in 2019.[7]
The grayish mouse opossum (Tlacuatzin canescens) is a species of opossum endemic to Mexico. It is the sole species in the genus Tlacuatzin.
