''Pseudemoia entrecasteauxii'', also known commonly as Entrecasteaux's skink, the southern grass skink, the tussock cool-skink, and the tussock skink, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Scincidae. The species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Australia.

Geographic range

''P. entrecasteauxii'' is found in the south-east of the continent of Australia, as well as in

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

and the islands of Bass Strait.

Habitat

Although it occurs in a variety of habitats, ''P. entrecasteauxii'' is most commonly found in open grassy

woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...

s. Cogger HG (1979). ''Reptiles and Amphibians of Australia''. Sydney: Reed.

Longevity

The southern grass skink has a lifespan of about 5 or 6 years.

Description

''P. entrecasteauxii'' grows up to in length (not including the tail). Male skinks change colouration during the breeding season.

Etymology

The specific name, ''entrecasteauxii'', is in honor of French naval officer and explorer

Antoine Bruni d'Entrecasteaux Antoine Raymond Joseph de Bruni, chevalier d'Entrecasteaux (; 8 November 1737 – 21 July 1793) was a French Navy officer, explorer and colonial administrator who served as the Governor of Isle de France (Mauritius), governor of Isle de Fran ...

Reproductive biology

The southern grass skink has become a model species for reproductive biology in reptiles because it gives birth to live young and exhibits non-invasive epitheliochorial

placentation Placentation is the formation, type and structure, or modes of arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to re ...

. Unlike the majority of live bearing reptiles, ''Pseudemoia'' develop complex placentae, which provide a substantial amount of nutrients to the embryo through pregnancy. Pregnancy in squamates is supported by the evolution of a novel state of gene regulation. The amount of nutrients provided is dependent on the amount of food females consume during pregnancy, and, unlike other live-bearing reptiles, scarcity of food during pregnancy can cause developmental failure. When food is limiting, females will also cannibalize their offspring. Together, these results suggest that placental nutrient transport may only be a successful mode of reproduction if food is abundant throughout pregnancy, which may limit its opportunities to evolve in some reptiles. Lipid transport in this species most likely occurs through the yolk sac placenta and is facilitated in part by the production of the protein

lipoprotein lipase Lipoprotein lipase (LPL) (EC 3.1.1.34, systematic name triacylglycerol acylhydrolase (lipoprotein-dependent)) is a member of the lipase gene family, which includes pancreatic lipase, hepatic lipase, and endothelial lipase. It is a water-solubl ...

. The first observation of an extra-uterine pregnancy in a

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

was found in this species. The extra-uterine

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

did not invade maternal tissue, suggesting fundamental differences between the nature and

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

of placentation in the southern grass skink and eutherian

mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...