Saiphos

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Saiphos
Yellow-bellied three-toed skink.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Scincidae
Genus: Saiphos
Gray, 1830
Species:
S. equalis
Binomial name
Saiphos equalis
(Gray, 1825)
Three-toed Skink.png
Distribution of the Yellow-bellied three-toed Skink
Synonyms [2] [3] [4] [5] [6]
  • Seps equalisGray, 1825
  • Anguis lacertinaGray, 1831
    ( nomen nudum )
  • Siaphos[ sic ]aequalis
    — Gray, 1839
    (emendation)
  • Lygosoma (Siaphos) aequale
    Longman, 1915
  • Saiphos aequalis
    Greer et al., 2006
  • Siaphos aequalis(Gray, 1839)
  • Saiphos samueliWells & Wellington, 1985
  • Saiphos equalis
    Cogger, 1983

Saiphos equalis, commonly known as the yellow-bellied three-toed skink or simply three-toed skink, is a species of burrowing skink found in eastern Australia. It is the only species classified under the genus Saiphos.

The lizard has attracted scientific attention due to its dual reproduction habits of producing young via eggs in coastal populations, or via live young in colder mountain regions. [7]

Description

Saiphos equalis grows to a length of 18 cm (7.1 in) including the tail. It has a brown back and an orange belly. The skink is active at night, and feeds on insects. Along the coastal lowlands of Australia, the skink has been observed laying eggs and giving birth to live young for reproduction. Individuals of the species in the lowlands lay eggs (oviparous), while its neighbors to the north in the mountains are almost exclusively giving birth to live young (viviparous). [7] [8]

Taxonomy and nomenclature

Saiphos equalis was originally described by the British zoologist John Edward Gray in 1825 as Seps equalis. [9] In 1831, Gray reclassified it under a genus he separately established, Saiphos. [3]

Saiphos equalis is now considered to be the only member of the genus Saiphos. It belongs to the subfamily Lygosominae of the skink family Scincidae. [10] Phylogenetic analysis in 2003 showed that the closest sister taxa of Saiphos equalis are Coeranoscincus reticulatus and members of the genus Ophioscincus . [11] They are part of the Australian Sphenomorphus group, a large monophyletic clade within Lygosominae. [12]

Distribution and habitat

Saiphos equalis are common in New South Wales and Queensland of eastern Australia. [13]

Reproduction

Saiphos equalis includes populations of three main reproductive modes: oviparous with long (15 days) incubation periods, viviparous with no incubation period (0 days), and intermediate populations that are oviparous with short (~5 days) incubation periods. No populations of this skink exhibit normal scincid oviparity behavior with greater-than-30-day incubation periods, which could further indicate this skink is truly making the transition to exclusively viviparity. [14]

In a study, published in 2001, of coastal Saiphos equalis populations, mitochondrial nucleotide sequences (ND2 and cytochrome b) were used to organize the relationships among the various populations. According to Smith et al. the analysis suggests that the long incubation period oviparous lineage is the sister group to the other short-period oviparous and viviparous populations. These clades are consistent and correspond to variation in reproductive modes as well as geographic location according to latitude and altitude. [15]

Lizards from high elevation sites (greater than 1,000 m (3,300 ft)) in north-eastern New South Wales are viviparous, while low-elevation populations from northern and southern in New South Wales exhibit short-period oviparity, an intermediate between viviparity and typical oviparous behaviors. [16] The viviparous populations give birth to fully developed offspring in transparent membranes, while the short-day oviparous populations give birth to partly shelled eggs that contain mostly developed embryos. The embryo continues to develop in the egg prior to hatching. In the northernmost coastal region of New South Wales, the lizards have relatively long incubation periods (approximately 15 days), and the eggshells are thicker. [11]

In April 2019 Saiphos equalis made news when researchers from the University of Sydney reported observing a female laying eggs and giving birth to live young from the same pregnancy, the first reported observation of a vertebrate doing this. [17]

Related Research Articles

<span class="mw-page-title-main">Skink</span> Family of reptiles

Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. Skinks are characterized by their smaller legs in comparison to typical lizards and are found in different habitats except arctic and subarctic regions.

<i>Egernia</i> Genus of lizards

Egernia is a genus of skinks that occurs in Australia. These skinks are ecologically diverse omnivores that inhabit a wide range of habitats. However, in the loose delimitation the genus is not monophyletic but an evolutionary grade, as has long been suspected due to its lack of characteristic apomorphies.

<i>Eulamprus</i> Genus of lizards

Eulamprus is a genus of lizards, commonly known as water skinks, in the subfamily Sphenomorphinae of the family Scincidae. The genus is native to Australia.

<i>Lygosoma</i> Genus of lizards

Lygosoma is a genus of lizards, commonly known as supple skinks or writhing skinks, which are members of the family Scincidae. Lygosoma is the type genus of the subfamily Lygosominae. The common name, writhing skinks, refers to the way these stubby-legged animals move, snake-like but more slowly and more awkwardly.

<span class="mw-page-title-main">Viviparity</span> Development of the embryo inside the mother

In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juvenile that is at least metabolically independent. This is opposed to oviparity, where the embryos develop independently outside the mother in eggs until they are developed enough to break out as hatchlings; and ovoviviparity, where the embryos are developed in eggs that remain carried inside the mother's body until the hatchlings emerge from the mother as juveniles, similar to a live birth.

<span class="mw-page-title-main">Oviparity</span> Animals that lay their eggs, with little or no other embryonic development within the mother

Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings known as hatchlings with little or no embryonic development within the mother. This is the reproductive method used by most animal species, as opposed to viviparous animals that develop the embryos internally and metabolically dependent on the maternal circulation, until the mother gives birth to live juveniles.

<span class="mw-page-title-main">Lygosominae</span> Subfamily of lizards

Lygosominae is the largest subfamily of skinks in the family Scincidae. The subfamily can be divided into a number of genus groups. If the rarely used taxonomic rank of infrafamily is employed, the genus groups would be designated as such, but such a move would require a formal description according to the ICZN standards.

<span class="mw-page-title-main">Bougainville's skink</span> Species of lizard

Bougainville's skink is a species of skink, a lizard in the family Scincidae. This species is also commonly called the south-eastern slider and Bougainville's lerista.

<span class="mw-page-title-main">Eastern three-lined skink</span> Species of lizard

The eastern three-lined skink, also known commonly as the bold-striped cool-skink, is a species of skink, a lizard in the family Scincidae. The species is endemic to Australia. A. duperreyi has been extensively studied in the context of understanding the evolution of learning, viviparity in lizards, and temperature- and genetic-sex determination. A. duperreyi is classified as a species of "Least Concern" by the IUCN.

<i>Pseudemoia entrecasteauxii</i> Species of lizard

Pseudemoia entrecasteauxii, also known commonly as Entrecasteaux's skink, the southern grass skink, the tussock cool-skink, and the tussock skink, is a species of lizard in the family Scincidae. The species is endemic to Australia.

<i>Oligosoma suteri</i> Species of lizard

Oligosoma suteri, known commonly as Suter's skink, the black shore skink, the egg-laying skink, and Suter's ground skink, is a species of lizard in the family Scincidae. The species is endemic to New Zealand.

<i>Chioninia</i> Genus of lizards

Chioninia is a genus of skinks, lizards in the subfamily Lygosominae. For long, this genus was included in the "wastebin taxon" Mabuya. The genus Chioninia contains the Cape Verde mabuyas.

<i>Lankascincus deignani</i> Species of lizard

Lankascincus deignani, commonly known as Deignan's tree skink and the Deignan tree skink, is a species of lizard in the family Scincidae. The species is endemic to the island of Sri Lanka.

Lankascincus dorsicatenatus, also known as the catenated lankaskink, is a species of skink, a lizard in the family Scincidae. The species is endemic to island of Sri Lanka.

<i>Concinnia</i> Genus of lizards

Concinnia is a genus of skinks in the subfamily Lygosominae.

<i>Kaestlea</i> Genus of lizards

Kaestlea is a genus of skinks. These skinks are small, shiny, smooth-scaled species. They are diurnal, terrestrial and insectivorous. They lay eggs to reproduce. These skinks are identified by their distinct blue tail colour. They live in tropical rainforest and montane forest habitats. These secretive skinks silently move through thick leaf-litter on forest floor. They are all endemic to the Western Ghats mountains and in some parts of Eastern Ghats (Shevaroys) of South India.

<span class="mw-page-title-main">Stokes's skink</span> Species of lizard

Egernia stokesii is a gregarious species of lizard of the Scincidae family. This diurnal species is endemic to Australia, and is also known as the Gidgee skink, spiny-tailed skink, Stokes's skink and Stokes's egernia. The species forms stable, long-term social aggregations, much like the social groups seen in mammalian and avian species. This characteristic is rarely found in the Squamata order, but is widespread within the Australian subfamily of Egerniinae skinks. Populations of E. stokesii are widely distributed, but fragmented, and occur in semi-arid environments. There are three recognised subspecies. The conservation status for the species is listed as least concern, however, one subspecies is listed as endangered.

<span class="mw-page-title-main">Sphenomorphinae</span> Subfamily of skinks

Sphenomorphinae is a large subfamily of skinks, lizards within the family Scincidae. The genera in this subfamily were previously found to belong to the Sphenomorphus group in the large subfamily Lygosominae.

<i>Silvascincus tryoni</i> Species of lizard

Silvascincus tryoni, the Border Ranges blue-spectacled skink or forest skink, is a species of lizard in the family Scincidae. It is endemic to the McPherson Range bordering New South Wales and Queensland, Australia.

Sphenomorphus derooyae is a species of skink, a lizard in the family Scincidae. The species is native to Oceania.

References

  1. Shea G, Clemann N, Hutchinson M, Chapple D (2018). "Saiphos equalis ". The IUCN Red List of Threatened Species 2018: e.T109481120A109481148. https://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T109481120A109481148.en. Downloaded on 15 September 2018
  2. Saiphos at the Reptarium.cz Reptile Database. Accessed 3 April 2020.
  3. 1 2 John Edward Gray (1831). "A synopsis of the species of Class Reptilia Volume IX: The Class Reptilia". In Edward Griffith; Edward Pidgeon (eds.). The animal kingdom arranged in conformity with its organisation by the Baron Cuivier with additional descriptions of all the species hither named, and of many before noticed. Whittaker, Treacher, and Co., London. p. 72. ISBN   9780127826226.
  4. Karl P. Schmidt (1943). "Amphibians and Reptiles from the Sudan" (PDF). Zoological Series of Field Museum of Natural History. 24 (29): 331–338.
  5. Peter Uetz; Jakob Hallermann & Jiri Hosek. "Saiphos equalis (Gray, 1825)". The Reptile Database.
  6. Glenn M. Shea & Ross A. Sadlier (1999). "A Catalogue of the Non-fossil Amphibian and Reptile Type Specimens in the Collection of the Australian Museum: Types Currently, Previously and Purportedly Present" (PDF). Technical Reports of the Australian Museum. 15 (15). Australian Museum: 1–91. doi: 10.3853/j.1031-8062.15.1999.1290 . ISSN   1031-8062.
  7. 1 2 Marshall,M., Live birth, evolving before our eyes, New Scientist, 25 August 2010.
  8. Linville, Brent J.; Stewart, James R.; Ecay, Tom W.; Herbert, Jacquie F.; Parker, Scott L.; Thompson, Michael B. (2010). "Placental calcium provision in a lizard with prolonged oviductal egg retention". Journal of Comparative Physiology B. 180 (2): 221–227. doi:10.1007/s00360-009-0400-2. PMID   19727762.
  9. John Edward Gray (1825). "A synopsis of the genera of reptiles and Amphibia, with a description of some new species". Annals of Philosophy . 10. British Museum: 193–217.
  10. George R. Zug; Laurie J. Vitt & Janalee P. Caldwell (2001). Herpetology: an Introductory Biology of Amphibians and Reptiles. Academic Press. p. 494. ISBN   978-0-12-782622-6.
  11. 1 2 Reeder, Tod W. (2003). "A phylogeny of the Australian Sphenomorphus group (Scincidae: Squamata) and the phylogenetic placement of the crocodile skinks (Tribolonotus): Bayesian approaches to assessing congruence and obtaining confidence in maximum likelihood inferred relationships". Molecular Phylogenetics and Evolution. 27 (2003): 384–397. doi:10.1016/S1055-7903(02)00448-7. PMID   12742744.
  12. Skinner, Adam (2007). Phylogeny and Evolution of Lerista (Lygosominae, Scincidae, Squamata) (PDF) (PhD thesis). Department of Environmental Biology, The University of Adelaide.
  13. Queensland CRA/RFA Steering Committee (1997). Systematic Vertebrate Fauna Survey Project: Stage IIB – Assessment of Habitat Quality for Priority Species in Southeast Queensland Bioregion (PDF) (Report). Department of Natural Resources, Department of Environment, and Environment Australia, Queensland Government, Government of Australia. pp. 71–72. Archived from the original (PDF) on 2011-06-07.
  14. de Fraipont, M.; Clobert, J.; Barbault, R. (1996). "The evolution of oviparity with egg guarding and viviparity in lizards and snakes: A phylogenetic analysis". Evolution. 50 (1): 391–400. doi:10.1111/j.1558-5646.1996.tb04501.x. JSTOR   2410809. PMID   28568867.
  15. Smith, Sarah A.; Austin, Christopher C.; Shine, Richard (2001). "A phylogenetic analysis of variation in reproductive mode within an Australian lizard (Saiphos equalis, Scincidae)". Biological Journal of the Linnean Society. 74 (2): 131–139. doi: 10.1111/j.1095-8312.2001.tb01382.x .
  16. Smith, Geoffrey R.; Ballinger, Royce E.; Congdon, Justin D. (1993). "Thermal ecology of the high-altitude bunch grass lizard, Sceloporus scalaris". Canadian Journal of Zoology. 71 (11): 2152–2155. doi:10.1139/z93-302.
  17. "Which came first, the lizard or the egg?". sydney.edu.au. 3 April 2019. Retrieved 5 April 2019.

Further reading