Fat-tailed pseudantechinuses (Pseudantechinus macdonnellensis) are endemic to Australia, and they are found in the uplands of central Australia with a distribution including much of the central and northern share of the state of Western Australia, the southern two-thirds of the Northern Territory, as well as the northwestern quarter of South Australia.
They are found as far south as Copper Hills, South Australia, and their northern range stretches northward to Fish River Gorge Block National Park, Northern Territory. Their eastern range extends to the western edge of the Simpson Desert in South Australia, and westward they occupy much of the Gibson Desert, the northern fringes of the Great Victoria Desert, and the southern and eastern outskirts of the Gibson Desert in Western Australia. Beyond that, the western populations, synonymously known as Rory Cooper's false antechinuses (Pseudantechinus roryi), are found in the Pilbara Uplands stretching towards the coast with their western range ending with the Indian Ocean.
In 2010, there was an isolated population detected in Queensland along the eastern fringes of the Simpson Desert. Also, in Western Australia, there are presumably isolated populations located on Barrow Island and the North West Cape peninsula. (Baker and Dickman, 2018; Burbidge, et al., 2016; Cooper, et al., 2000; Menkhorst and Knight, 2011; Nowak, 2005; Van Dyck and Strahan, 2008; Woinarksi, et al., 2016; Woolley, 1991)
Fat-tailed pseudantechinuses are habitat specialists. Restricted to arid regions, they are primarily found within rocky habitats. Microhabitats can include crags, cliffs, breakaways, talus slopes and scree fields, sandstone outcrops, granite rock piles, and stony hills. They also live in or around termite mounds, especially within the red sandplains of the Tanami and western Simpson deserts.
In Western Australia, the habitats of the synonymous western variant, Rory Cooper's false antechinuses (Pseudantechinus roryi), are similar, with dry and rocky areas hosting them. Yet, they will inhabit savannahs, shrub steppes, and hummock grasslands including spinifex plains and basins. More rarely, they are also found in low-lying open woodlands.
Fat-tailed pseudantechinuses require burrows needed for torpor to minimize energy waste, water loss, and exposure to potential predators. They also require basking sites within their habitat. These requirements make fat-tailed pseudantechinuses habitat specialists, resulting in scattered colonies across their geographic range.
No elevational range has been reported. (Armati, et al., 2006; Baker and Dickman, 2018; Burbidge, et al., 2016; Gilfillan, 2001a; Menkhorst and Knight, 2011; Nowak, 2005; Pavey and Geiser, 2008; Van Dyck and Strahan, 2008; Woinarksi, et al., 2016)
Fat-tailed pseudantechinuses are dasyurid marsupials that possess a sparingly-furred “carrot”-shaped tail that is shorter than the body (Menkhorst and Knight, 2011). This namesake tail, which is wide at the base and tapers off, can store fat for survival during harsh conditions. Their dorsal fur can range from gingery brown-grey to an orange-red color, and they possess a white ventral fur coat. A distinguishing feature of most species within this genus is a bright orange, chestnut patch right behind each of their large ears, which are 13 to 19 mm in length. They also have distinctive broad hind feet that are 12 to 15 mm long. Males have an additional penile appendage with an unknown function, and females always have six teats.
Adult males weigh 19 to 45 g and adult females weigh 17 to 40 g. Males measure 83 to 105 mm from the tip of their muzzle to the base of their tail, and females have a head and body length of 77 to 105 mm. Males' tails measure 66 to 80 mm, and female tail length can range from 66 mm to 85 mm. Overall, the total body length including the tail falls between 143 to 190 mm for both sexes.
Their carnivorous nature is reflected in the dental characteristics in fat-tailed pseudantechinuses. They have a dental formula of 4124/3124 and incisors are sharp. They possess 2 less pronounced premolars, compared to three premolars of other dasyurids. Their sharp muzzle could also be reflective of their insectivorous nature.
Western populations, synonymously Rory Cooper's false pseudantechinuses (Pseudantechinus roryi), have a bicolor tail matching their white ventral fur. These western populations also have a bright red-brownish fur more closely matching the characteristic Pilbara region’s red soils. Beyond that, clinical variation exists and western populations are smaller than their central counterparts. On average, they weigh 9 g less, their combined head and body lengths are shorter by 16 mm, and their tails are 4 mm shorter.
Juveniles look similar to adults, save for females lacking a fully-developed pouch and males possessing a smaller scrotal width than adults. Juveniles weigh less than 15 g. Not much is known about the characteristics of neonates due to their altricial (extremely undeveloped) state confining them to the internals of their mothers’ pouches.
Similar-looking species include others within the genus: Woolley's pseudantechinuses (Pseudantechinus woolleyae), Ningbing pseudantechinuses (Pseudantechinus ningbing), Alexandria false antechinuses (Pseudantechinus mimulus), and sandstone dibblers (Pseudantechinus bilarni). Woolley's pseudantechinuses are usually larger and have a third lower premolar with a dental formula of 4124/3134. Ningbing pseudantechinuses are smaller with proportionally longer tails, and the females of that species only have four teats. Alexandria false antechinuses have normal upper third premolars (compared to those greatly reduced in Pseudantechinus macdonnelensis). Sandstone dibblers have a much proportionally longer and skinnier tail. Fat-tailed dunnarts (Sminthopsis crassicaudata) are usually smaller and do not possess the same chestnut patches behind the ears like the rest of the pseudantechinuses. (Baker and Dickman, 2018; Cooper, et al., 2000; Menkhorst and Knight, 2011; Nowak, 2005; Van Dyck and Strahan, 2008; Walton and Richardson, 1989)
Fat-tailed false antechinuses are a life-history strategy two species. Females are monoestrous (breeding once annually during the Australian winter), and breed for three seasons. Males attempt to reproduce for two breeding seasons.
Female fat-tailed false antechinuses ovulate spontaneously, and mate either at the peak of their estrous cycle when they have the most body mass or shortly thereafter. Copulation can last 30 minutes to two hours, resulting in fertilization of eggs released from the female's ovaries.
While dasyurids are generally promiscuous, the specific mating systems of Pseudantechinus macdonnellensis are unknown. (Armati, et al., 2006; Gilfillan, 2001b; Nowak, 2005; Van Dyck and Strahan, 2008; Woolley, 1991)
The breeding season for Pseudantechinus macdonnellensis varies geographically, with eastern populations in central Australia breeding in June and July, and western populations in August and September.
The gestation period ranges from 45 to 55 days, after which young are birthed and kept in the mother’s pouch. Litter sizes are five or six offspring, representative of the six teats of all females. There is no reported average birth mass, but Woolley (1991) reported a neonate birthed within 24 hours weighing 12.3 micrograms. That same neonate was 3.8 mm in length from the crown to the rump.
After birth, young depend on their mother and are nursed until they are weaned at 14 weeks old. Both males and females reach sexual maturity the same year that they are born, able to breed at an average of 11 months. Unlike some dasyurids (i.e. subtropical antechinuses Antechinus subtropicus), male fat-tailed false antechinuses can survive for more than just a single breeding season. Males can survive to reproduce in up to three breeding seasons (typically two), and females can survive for four (typically three). (Armati, et al., 2006; Baker and Dickman, 2018; Gilfillan, 2001b; Menkhorst and Knight, 2011; Nowak, 2005; Van Dyck and Strahan, 2008; Woolley, 1991)
After birth, young are kept inside and protected by their mother’s pouch where they suckle from one of six teats for nourishment. At ca. 40 days after birth, young are left alone in the nest outside of their mother's pouch. The eyes of the offspring start to open at an age of 60 to 65 days, and at 70 days old, young are able to independently move from the nest. Young are completely weaned off of their mother at around 14 weeks.
Beyond the act of mating, males have no known efforts in parental investment. (Baker and Dickman, 2018; Gilfillan, 2001b; Nowak, 2005; Woolley, 1991)
In the wild, one fat-tailed pseudantechinus in Alice Springs lived for five years and eleven months.
In captivity, the longest recorded lifespan is seven years.
The daily torpor and basking activity of fat-tailed pseudantechinuses are presumed to have a beneficial effect on their lifespans, allowing them to survive for multiple breeding seasons and continue to live for years after reaching infertility. (Geiser and Pavey, 2007; Gilfillan, 2001b; Gilfillan, 2001a; Pavey and Geiser, 2008)
Fat-tailed pseudantechinuses are primarily nocturnal, foraging in the night and crepuscular hours. Fat-tailed pseudantechinuses, like most dasyurids, enter into a state of daily torpor to conserve energy and water loss. Their mean body temperature is ca. 35 degrees C, but during their daily torpor their average minimum temperature drops to 24.8 degrees C. The minimum recorded temperature in a female was 15.7 degrees C.
During the Australian winter (May to August), fat-tailed pseudantechinuses have a diel cycle of undergoing torpor during the latter half of the night (instead of the day) and subsequent rewarming during the morning hours by basking on rocks at their habitat. They also forage diurnally immediately after rewarming, as well as bouts closer to sunset. Some explanations for this shift in activity is that fewer predator species are active during the winter making diurnal basking and foraging less risky. During the summer, they return to being nocturnal.
Fat-tailed pseudantechinus have a more stable home range in comparison to other dasyurids in Australia’s dry areas. Their rocky habitats provide sufficient shelter, sustainable food sources, and areas for burrowing, basking, and foraging, with no need for long range movements. Gilfillan (2001a) asserts that these stable conditions result in an increased longevity for Pseudantechinus macdonnellensis in comparison to other dasyurids of similar size. (Geiser and Pavey, 2007; Gilfillan, 2001b; Menkhorst and Knight, 2011; Pavey and Geiser, 2008; Pavey, et al., 2003; Van Dyck and Strahan, 2008)
Pavey et al. (2003) used the minimum convex polygon model to report a mean home range of fat-tailed pseudantechinus as 7600 square meters. Males were active over 9800 square meters while females used 3100 square meters. Using the 95% fixed kernel model, the mean home range was 11400 square meters, with males occupying 15000 square meters compared to females' 4300 square meters. Core areas, represented by the 50% kernel contour model, encompassed an average area of 700 square meters for both sexes. The average maximum range length was 148.83 meters, with males having a maximum range length of 180.25 meters, and females just 86.0 meters. Home ranges of individuals of the same sex overlapped very little, yet the home ranges of males overlapped those of females by 38%.
Territory size has not been published for this species. (Gilfillan, 2001a; Pavey, et al., 2003; Van Dyck and Strahan, 2008)
Like most mammals, fat-tailed pseudantechinuses perceive their environment through visual, tactile, acoustic, and chemical stimuli. The social interactions of fat-tailed pseudantechinuses are little studied, but in other small dasyurids, females exhibit mating squeaks that are reciprocated by males and followed by sudden movement. Tactile responses are common between a male and female while mating and between a female and her young in the pouch.
It is predicted that Australian marsupials have trichromatic vision (and are thus able to see in color due to a combination of red, blue, and green rods, similar to primates), but further research is needed to confirm that this is the case for this genus. (Armati, et al., 2006; Cowing, et al., 2008; Walton and Richardson, 1989)
Being primarily generalist insectivores, fat-tailed pseudantechinuses consumes a wide variety of insects, most particularly termites (Isoptera), beetles (Coleoptera), grasshoppers (Orthoptera), butterflies (Lepidoptera), and invertebrate larvae. In total, 10 orders of insects are identified as prey of fat-tailed pseudantechinuses. They opportunistically consume any terrestrial invertebrate they find. Other non-insect prey accounts include spiders (Arachnida), snails (Gastropoda), woodlice (Malacostraca), and even rodents. It is unknown whether fat-tailed pseudantechinuses actively hunt rodents or simply take them as carrion.
Gilfillan (2001a) studied the diet of these marsupials, and determined that termites were found in the fecal pellets of fat-tailed pseudantechinuses the most, and thus made up the largest percentage of their diet in comparison to other insect orders. Also, grasshoppers were consistently found in the diets of fat-tailed pseudantechinuses despite seasonal fluctuation in availability, and beetles were found in fecal pellets more often than relative availability in biomass would suggest. Overall, the study found that the greatest percentage of fecal pellets included termites (69%), beetles (63%), grasshoppers (42%), spiders (29%), and wasps/bees (28%). Additionally, unidentifiable invertebrate larvae were found in 33% of examined fecal pellets. Multiple orders of insects were found in almost every examined pellet. (Baker and Dickman, 2018; Burwell, et al., 2005; Edwards, 2013; Gilfillan, 2001b; Menkhorst and Knight, 2011; Walton and Richardson, 1989)
Humans (Homo sapiens), specifically indigenous Australians, are known to hunt fat-tailed pseudantechinuses for sustenance either by catching them off guard at the entrance of a termite mound or taking advantage of the animals’ behavior of basking. In addition, black-headed monitors (Varanus tristis) have been observed attempting to prey on fat-tailed pseudantechinuses.
Presumed predators include varanid lizards such as perenties (Varanus giganteus) and spiny-tailed monitors (Varanus acanthurus). Other presumed predators are snakes, such as Stimson's pythons (Antaresia stimsoni), centralian carpet pythons (Morelia bredli), desert death adders (Acanthophis pyrrhus), mulga snakes (Pseudechis australis), gwardars (Pseudonaja nuchalis), and eastern brown snakes (Pseudonaja textilis). Presumed predatory birds of prey include whistling kites (Haliastur sphenurus), brown goshawks (Accipiter fasciatus), brown falcons (Falco berigora), Australian kestrels (Falco cenchroides), tawny frogmouths (Podargus strigoides), moreporks (Ninox novaeseelandiae), and barn owls (Tyto alba). Other introduced presumed predators include feral cats (Felis catus) and dingos (Canis lupus dingo).
Western populations (synonymously Rory Cooper's false pseudantechinuses Pseudantechinus roryi) have a red-brownish fur that resembles their geographic region’s red soils, helping them blend in within their environment. (Baker and Dickman, 2018; Pavey, et al., 2003; Van Dyck and Strahan, 2008)
Fat-tailed pseudantechinuses are carnivorous and generally consume insects, yet they are preyed on by tertiary consumers such as birds of prey, lizards and snakes, or feral cats (Felis catus).
The only confirmed endoparasite for fat-tailed pseudoantechinuses is the apicomplexan protozoan, Toxoplasma gondii.
Common ectoparasites of dasyurids are mites (Astigmata), ticks (Ixodida) and fleas (Siphonaptera). Sandstone dibblers (Pseudantechinus bilarni) are commonly parasitized by lice (Phthiraptera). Endoparasites of dasyurids include roundworms (Nematoda), liver flukes (Trematoda), tapeworms (Cestoda), and protozoans. It is possible that fat-tailed pseudantechinuses could host these parasites, as well. (Attwood, et al., 1975; Burwell, et al., 2005; Walton and Richardson, 1989)
Historically, indigenous Australians have hunted fat-tailed pseudantechinuses for food, and it is possible some tribes still do so. (Baker and Dickman, 2018; Van Dyck and Strahan, 2008)
There are no known negative economic effects of fat-tailed pseudantechinuses on humans.
The IUCN Red List has the status of Pseudantechinus macdonnellensis listed as “Least Concern.” The US Federal List, the CITES appendices, and the State of Michigan List all have no special status for fat-tailed pseudantechinuses.
Threats for fat-tailed pseudantechinuses include non-native carnivorous species, especially feral cats (Felis catus).
Fat-tailed pseudantechinuses are assumed to be common within suitable habitats. A significant portion of their range geographically falls under Australian national parks or other protected and monitored areas. Therefore, no conservation efforts are in place. (Baker and Dickman, 2018; Burbidge, et al., 2016; Pavey and Geiser, 2008; Woinarksi, et al., 2016)
In 2018, Umbrello et al. published an analysis of nuclear and mitochondrial gene sequences. They proposed that, despite some clinical variation and morphological differences over a vast geographic range, fat-tailed false antechinuses (Pseudantechinus macdonnellensis) and Rory Cooper's false antechinuses (Pseudantechinus roryi) are taxonomically synonymous species due to a lack of genetic boundaries. This taxonomic disagreement has been borne in mind for this account, and was written under the assumption that both species are now synonymous.
Rory Cooper's false antechinuses (now referred to as a western variant of fat-tailed false antechinuses) were found throughout the Northern Pilbara region with its range stretching into the Gibson and Great Sandy Deserts. Also, the false antechinuses populations on Barrow Island and North West Cape peninsula were presumed to be Pseudantechinus roryi (now Pseudantechinus macdonnellensis), but further research is needed to confirm whether these are just geographical isolated populations or an unrepresented species. (Cooper, et al., 2000; Menkhorst and Knight, 2011; Umbrello, et al., 2018)
Christopher Wozniak (author), Radford University, Logan Platt (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
flesh of dead animals.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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