Plains rat

The name Pseudomys comes from the combined form of the Greek word pseudes (meaning "false") and the Latin word mys (meaning "mouse"), presumably because of the plains rat's puzzling similarities and differences to "true mice" in the genus mus. The name australis comes from the Latin word australis (meaning "south land"). Thus, the name Pseudomys australis, first described by Grey in 1832, means 'false mouse from the southern land'. The taxonomy of Australian rodents remains controversial; however, it is commonly accepted that there are two major groups including the Australo-Papuan Old Endemics and the Australo-Papuan New Endemics. The plains rat is considered an Australo-Papuan Old Endemic as DNA sequencing from fossilised evidence suggests that its ancestors first arrived in Australia between 4.2 and 5 million years ago, during the Pliocene era. Old endemics, particularly the Family Muridae, are believed to have originated in Southern Asia and then diversified through multiple rodent lineages. Relationships between Australian members of the Order Rodentia suggest that a New Guinean lineage gave rise to the Australo-Papuan Old Endemics and thus the early ancestors of the plains rat. contributing to difficulties in determining the differences between populations of the same species and different species within the Genus Pseudomys. == Distribution and habitat ==

The primary extant population of the plains rat can be divided into five broad geographic zones: 1) the Arcoona Tableland, SA; 2) the Southern Lake Eyre region, SA; 3) the Moon Plain region, SA; 4) the Oodnadatta region (including Witjira National Park), SA/NT; and, 5) the Andado Station and Mac Clark Conservation Reserve, NT. however, the current assumed distribution of the plains rat is limited to the gibber (stone-covered) plains in central-northern South-Australia. These areas are characterised by cracking clay, productive depressions and minor drainage lines which support low open scrublands and ephemeral grass or herb lands. Similarly, during times of high rainfall, populations displaced due to flood inundation may migrate temporarily into surrounding habitat types. == Physical description ==

The plains rat has a stocky build of around 65 grams with long ears and a rounded muzzle and is grey to brown along its back with white or cream lining its underbelly. Its combined head and body length is usually between 90 and 145 millimetres and its tail is roughly as long as its body. During lactation, females can be observed dragging their young as they each latch to one of the four teats located on its underbelly. == Behaviour and ecology ==

The plains rat constructs a complex system of shallow connected tunnels beneath the cracking clay of gibber plains, emerging only at night to feed on seeds, stems and arthropods. The home range of an adult is roughly 1.6 hectares. Similarly, during severe drought most will only survive one year. == Threats ==

Habitat degradation, introduced predators and drought collectively threaten the survival of the plains rat. Hoofed stock lessen vegetation cover, crush the seed bank and trample burrows while land clearing removes food sources vital to the survival of the plains rat. Reduced vegetation cover and damaged burrows only makes it easier for introduced predators such as the European fox (Vulpes vulpes) and feral cat (Felis catus) to excavate shallow burrows. This can contribute to local extinctions, particularly when populations are already low during periods of drought. Other potential threats to the plains rat include altered fire regimes, leading to increased intensity of bushfires; competition with the introduced house mouse (Mus musculus) and European rabbit (Oryctolagus cuniculus); and, climate change. == Conservation ==

The Action Plan for Australian Mammals 2012 == See also ==