Pseudemoia entrecasteauxii

The southern grass skink (Pseudemoia entrecasteauxii) is a species of lizard in the family Scincidae. The species is endemic to Australia, where it is found in the south-east of the continent, as well as in Tasmania and the islands of Bass Strait. Although it occurs in a variety of habitats, it is most commonly found in open grassy woodlands.[3][4]

Pseudemoia entrecasteauxii

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Scincidae
Genus: Pseudemoia
Species:
P. entrecasteauxii
Binomial name
Pseudemoia entrecasteauxii
Distribution of the southern grass skink
Synonyms
  • Lygosoma entrecasteauxii A.M.C. Duméril & Bibron, 1839
  • Leilopisma entrecasteauxi
    — Greer, 1974
  • Claireascincus entrecasteauxii — Wells & Wellington, 1985
  • Pseudemoia entrecasteauxii
    — Hutchinson et al., 1990
  • Niveoscincus entrecasteauxii
    — Bauer et al., 1995[2]

The Southern grass skink has a lifespan of about 5 or 6 years. It grows up to 7.5 cm (3.0 in) 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.[5]

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. Unlike the majority of live bearing reptiles, Pseudemoia develop complex placentae, which provide a substantial amount of nutrients to the embryo through pregnancy.[6] Pregnancy in squamates is supported by the evolution of a novel state of gene regulation.[7] 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.[8] 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.[9] The first observation of an extra-uterine pregnancy in a reptile was found in this species.[10] The extra-uterine embryo did not invade maternal tissue, suggesting fundamental differences between the nature and evolution of placentation in southern grass skinks and eutherian mammals.

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References
  1. Gillespie, G., Hutchinson, M., Michael, D., Melville, J., Chapple, D.C, Clemann, N. & Robertson, P. 2018. Pseudemoia entrecasteauxii. The IUCN Red List of Threatened Species 2018: e.T109480964A109480977. https://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T109480964A109480977.en. Downloaded on 28 March 2020.
  2. "Pseudemoia entrecasteauxii ". The Reptile Database. www.reptile-database.org.
  3. DPIW: Native Plants and Animals – Southern Grass Skink
  4. Cogger HG. (1979). Reptiles and Amphibians of Australia. Sydney: Reed. ISBN 0-589-50108-9
  5. Beolens B, Watkins M, Grayson M. (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Pseudemoia entrecasteauxii, p. 84).
  6. Thompson, MB; Stewart, JR; Speake, BK; Russell, KJ; McCartney, RJ; Surai, PF (1999). "Placental nutrition in a viviparous lizard (Pseudemoia pagenstecheri) with a complex placenta". Journal of Zoology. 248 (3): 295–305. doi:10.1111/j.1469-7998.1999.tb01030.x.
  7. Griffith, Oliver W.; Brandley, Matthew C.; Belov, Katherine; Thompson, Michael B. (2016-10-01). "Reptile Pregnancy Is Underpinned by Complex Changes in Uterine Gene Expression: A Comparative Analysis of the Uterine Transcriptome in Viviparous and Oviparous Lizards". Genome Biology and Evolution. 8 (10): 3226–3239. doi:10.1093/gbe/evw229. ISSN 1759-6653. PMC 5174741. PMID 27635053.
  8. Van Dyke, JU; Griffith, OW; Thompson, MB (2014). "High food abundance permits the evolution of placentotrophy: evidence from a placental lizard, Pseudemoia entrecasteauxii". The American Naturalist. 184 (2): 198–210. doi:10.1086/677138. PMID 25058280.
  9. Griffith, OW; Ujvari, B; Belov, K; Thompson, MB (2013). "Placental lipoprotein lipase (LPL) gene expression in a placentotrophic lizard, Pseudemoia entrecasteauxii". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 320 (7): 465–470. doi:10.1002/jez.b.22526. PMID 23939756.
  10. Griffith, OW; Van Dyke, JU; Thompson, MB (2013). "No implantation in an extra-uterine pregnancy of a placentotrophic reptile". Placenta. 34 (6): 510–511. doi:10.1016/j.placenta.2013.03.002. PMID 23522396.
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