Egernia
Encyclopedia
Egernia is a genus
of skink
s (family
Scincidae) that occurs in Australia
. These skinks are ecologically diverse omnivore
s that inhabit a wide range of habitat
s. However, in the loose delimitation (which incorporates about 30 species
) the genus is not monophyletic but an evolutionary grade
, as has long been suspected due to its lack of characteristic apomorphies.
Some of the skinks traditionally placed in Egernia appear to be among the most intelligent squamates. They have been shown to be able to distinguish
between relatives and unrelated conspecifics, and can recognize relatives individually. Several species form monogamous pair-bonds. In that respect, it is interesting to note that most of these species belong to Egernia sensu stricto, and that similar behaviour is also known in the related Solomon Islands Skink
(Corucia zebrata). The latter means that the high intelligence and social skills are probably plesiomorphic for the Egernia genus-group as a whole, and that the solitary species appear to have evolved towards being less intelligent and social again. It may still be, however, that the intelligent behaviour is a homoplasy that evolved several times in the Egernia genus-group; the fact that Corucia is a monotypic
and rather distinct genus makes it impossible to decide at present.
(Corucia), Cyclodomorphus
and the blue-tongued skinks (Tiliqua). In some older works, it is considered closely related to Mabuya
, but even among the subfamily Lygosominae
this genus does not seem to be particularly closely related and would—were the genus-groups treated at the rarely-used rank of infrafamily—certainly constitute an infrafamily of its own. On the other hand, the enigmatic crocodile skinks (Tribolonotus) might be a very basal member of the Egernia genus-group.
The genus Egernia proper, as well as the other lineages, appear to be of Miocene
—probably Early Miocene
—origin, meaning they radiated at least 15, maybe 20 million years ago (mya). There are fossil
s of Egernia-like Lygosominae from around the Oligocene
-Miocene
boundary 23 mya, but these cannot be assigned to the present genus with certainty. Rather, they appear to be basal members of the Egernia genus-group, still very plesiomorphic Lygosominae with a habitus
similar to Mabuya
.
subunit
4, 12S rRNA, c-mos and β-fibrinogen
intron
7 DNA sequence
data delimits 4 clade
s in Egernia sensu lato, which are best regarded as separate genera
—as had already been proposed in former times, often as early as the 19th century:
Bellatorias Wells & Wellington, 1984 (= Hortonia)
Largish to very large skinks (adult snout-vent length 160–310 mm and more) with a bulky angular body and rather large eyes. 26–36 rows of midbody scales; dorsal
scales smooth or weakly keeled. The nasal scale has a postnarial groove running to the first supralabial scale; the subocular scale row is incomplete. Eyelids usually have conspicuous cream-coloured margins.
Egernia sensu stricto – spiny-tailed skinks and crevice-skinks
Mid-sized to large skinks (adult snout-vent length 100–240 mm) with a bulky, usually somewhat flattened body and small eyes. 24–46 rows of midbody scales; dorsal scales smooth, ridged, keeled or spiny (the tail is often notably spiny). The nasal scale has a postnarial groove; the subocular scale row is incomplete. Eyelids similar in colour to the adjacent scales.
Liopholis Fitzinger, 1843 (= Flamoscincus) – Australian desert and rock skinks
Smallish to largish-sized skinks (adult snout-vent length 75–200 mm) with a bulky angular body and rather large eyes. 34–52 rows of midbody scales; dorsal scales usually smooth. The nasal scale has no postnarial groove; the subocular scale row is incomplete. Eyelids usually have conspicuous cream-coloured margins.
Lissolepis Peters, 1872 – mourning skinks
Mid-sized skinks (adult snout-vent length 100–130 mm) with a bulky angular body and small eyes. 20–28 rows of midbody scales; dorsal scales smooth. The nasal scale has a postnarial groove; the subocular scale row is complete. Eyelids similar in colour to the adjacent scales.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of skink
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...
s (family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Scincidae) that occurs in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. These skinks are ecologically diverse omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
s that inhabit a wide range of habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s. However, in the loose delimitation (which incorporates about 30 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
) the genus is not monophyletic but an evolutionary grade
Evolutionary grade
In alpha taxonomy, a grade refers to a taxon united by a level of morphological or physiological complexity. The term was coined by British biologist Julian Huxley, to contrast with clade, a strictly phylogenetic unit.-Definition:...
, as has long been suspected due to its lack of characteristic apomorphies.
Some of the skinks traditionally placed in Egernia appear to be among the most intelligent squamates. They have been shown to be able to distinguish
Kin recognition
Kin recognition is animals' abilities to distinguish between close genetic kin and non-kin. In evolutionary biology and in psychology, such capabilities are presumed to have evolved to serve the adaptive functions of kin altruism and inbreeding avoidance...
between relatives and unrelated conspecifics, and can recognize relatives individually. Several species form monogamous pair-bonds. In that respect, it is interesting to note that most of these species belong to Egernia sensu stricto, and that similar behaviour is also known in the related Solomon Islands Skink
Solomon Islands skink
The Solomon Islands skink is an arboreal species of skink endemic to the Solomon Islands. It is the largest known extant species of skink...
(Corucia zebrata). The latter means that the high intelligence and social skills are probably plesiomorphic for the Egernia genus-group as a whole, and that the solitary species appear to have evolved towards being less intelligent and social again. It may still be, however, that the intelligent behaviour is a homoplasy that evolved several times in the Egernia genus-group; the fact that Corucia is a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
and rather distinct genus makes it impossible to decide at present.
Systematics, taxonomy and evolution
It is the namesake genus of the Egernia genus-group, which also includes the Solomon Islands SkinkSolomon Islands skink
The Solomon Islands skink is an arboreal species of skink endemic to the Solomon Islands. It is the largest known extant species of skink...
(Corucia), Cyclodomorphus
Cyclodomorphus
Cyclodomorphus is a genus of small to medium-sized skinks . It belongs to the Egernia group which also includes the blue-tongued skinks .-Species:*Cyclodomorphus branchialis...
and the blue-tongued skinks (Tiliqua). In some older works, it is considered closely related to Mabuya
Mabuya
Mabuya is a genus of long-tailed skinks nowadays restricted to species from the Americas. The American mabuyas are primarily carnivorous, though many are omnivorous. Formerly, many Old World species were placed here, as Mabuya was a kind of "wastebasket taxon"...
, but even among the subfamily Lygosominae
Lygosominae
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...
this genus does not seem to be particularly closely related and would—were the genus-groups treated at the rarely-used rank of infrafamily—certainly constitute an infrafamily of its own. On the other hand, the enigmatic crocodile skinks (Tribolonotus) might be a very basal member of the Egernia genus-group.
The genus Egernia proper, as well as the other lineages, appear to be of Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
—probably Early Miocene
Early Miocene
The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....
—origin, meaning they radiated at least 15, maybe 20 million years ago (mya). There are fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of Egernia-like Lygosominae from around the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
-Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
boundary 23 mya, but these cannot be assigned to the present genus with certainty. Rather, they appear to be basal members of the Egernia genus-group, still very plesiomorphic Lygosominae with a habitus
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
similar to Mabuya
Mabuya
Mabuya is a genus of long-tailed skinks nowadays restricted to species from the Americas. The American mabuyas are primarily carnivorous, though many are omnivorous. Formerly, many Old World species were placed here, as Mabuya was a kind of "wastebasket taxon"...
.
Splitting Egernia in four
Cladistic analysis of NADH dehydrogenaseNADH dehydrogenase
NADH dehydrogenase is an enzyme located in the inner mitochondrial membrane that catalyzes the transfer of electrons from NADH to coenzyme Q...
subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
4, 12S rRNA, c-mos and β-fibrinogen
Fibrinogen
Fibrinogen is a soluble plasma glycoprotein, synthesised by the liver, that is converted by thrombin into fibrin during blood coagulation. This is achieved through processes in the coagulation cascade that activate the zymogen prothrombin to the serine protease thrombin, which is responsible for...
intron
Intron
An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...
7 DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data delimits 4 clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
s in Egernia sensu lato, which are best regarded as separate genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
—as had already been proposed in former times, often as early as the 19th century:
Bellatorias Wells & Wellington, 1984 (= Hortonia)
Largish to very large skinks (adult snout-vent length 160–310 mm and more) with a bulky angular body and rather large eyes. 26–36 rows of midbody scales; dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
scales smooth or weakly keeled. The nasal scale has a postnarial groove running to the first supralabial scale; the subocular scale row is incomplete. Eyelids usually have conspicuous cream-coloured margins.
- Egernia frerei (Günther, 1897) – Major Skink
- Egernia major (Gray, 1845) – Land MulletLand MulletEgernia major, also known as Land Mullet, is one of the largest members of the skink family .The species may reach total lengths of up to 60 cm. They are uniform glossy black to brown, with a paler ring around the eye...
- Egernia obiri (Wells & Wellington, 1985) – Arnhem Land Skink (formerly E. arnhemensis)
Egernia sensu stricto – spiny-tailed skinks and crevice-skinks
Mid-sized to large skinks (adult snout-vent length 100–240 mm) with a bulky, usually somewhat flattened body and small eyes. 24–46 rows of midbody scales; dorsal scales smooth, ridged, keeled or spiny (the tail is often notably spiny). The nasal scale has a postnarial groove; the subocular scale row is incomplete. Eyelids similar in colour to the adjacent scales.
- Egernia cunninghami (Gray, 1832) – Cunningham's SkinkCunningham's SkinkCunningham's Skink is a large skink species native to southeastern Australia. It can reach up to 30 cm in length, and may be confused with blue-tongued lizards....
- Egernia depressa (Günther, 1875) – Pygmy Spiny-tailed Skink
- Egernia douglasi Glauert, 1956 – Kimberley Crevice-skink
- Egernia formosa Fry, 1914 – Goldfield's Crevice-skink (tentatively placed here)
- Egernia hosmeri Kinghorn, 1955 – Hosmer's Spiny-tailed Skink
- Egernia kingiiEgernia kingiiEgernia kingii, King's Skink, is a species of skink native to coastal regions of south-western Australia common on Rottnest Island and Penguin Island and some coastal areas with open forest and open heath...
(Gray, 1838) – King's Skink - Egernia mcpheei Wells & Wellington, 1984 – Eastern Crevice-skink, McPhee's Egernia
- Egernia napoleonis (Gray, 1838) – South-western Crevice-skink
- Egernia pilbarensis Storr, 1978 – Pilbara Crevice-skink
- Egernia richardi (Peters, 1869) – Bright Crevice-skink, Dark Spiny-tailed Skink (= E. carinata)
- Egernia rugosa De Vis, 1888 – Yakka Skink (tentatively placed here)
- Egernia saxatilis Cogger, 1960 – Black Crevice-skink, Black Rock Skink
- Egernia stokesii (Gray, 1845) – Gidgee Spiny-tailed Skink, Gidgee Skink, Stoke's Skink
- Egernia striolata (Peters, 1870) – Tree Crevice-skink, "tree skink"
Liopholis Fitzinger, 1843 (= Flamoscincus) – Australian desert and rock skinks
Smallish to largish-sized skinks (adult snout-vent length 75–200 mm) with a bulky angular body and rather large eyes. 34–52 rows of midbody scales; dorsal scales usually smooth. The nasal scale has no postnarial groove; the subocular scale row is incomplete. Eyelids usually have conspicuous cream-coloured margins.
- Egernia guthega Donnellan, Hutchinson, Dempsey & Osborne, 2002 – Guthega Skink, Snowy Mountains Skink, Alpine Egernia
- Egernia inornata (Rosén, 1905) – Unadorned Desert-skink, "desert skink"
- Egernia kintorei – Great Desert SkinkGreat Desert SkinkThe Great Desert Skink is a species of skink in the genus Egernia native to the western half of Australia . They are burrowing lizards and extremely social.- Description :...
- Egernia margaretae (Storr, 1968) – Centralian Ranges Rock-skink, Flinder's Ranges Rock-skink
- Egernia modesta (Storr, 1968) – Eastern Ranges Rock-skink
- Egernia montana Donnellan, Hutchinson, Dempsey & Osborne, 2002 – Mountain Egernia, "mountain skinkMountain SkinkMountain Skink may refer to:* Chalcides montanus from Morocco* Egernia montana from continental Australia* Eumeces callicephalus from Arizona, New Mexico, and north-western Mexico...
" - Egernia multiscutata (Mitchell & Behrndt, 1949) – Southern Sand-skink, Heath Skink, Bull Skink
- Egernia pulchra (Werner, 1910) – South-western Rock-skink, Spectacled Rock-skink
- Egernia slateri (Storr, 1968) – Centralian Floodplains Desert-skink, Slater's Egernia
- Egernia striata (Sternfeld, 1919) – Nocturnal Desert-skink, Night Skink, Striated Egernia
- Egernia whitii – White's SkinkWhite's SkinkWhite's Skink is a species of skink in the Scincidae family. It is found in south-eastern Australia, including Tasmania and many Bass Strait islands. It is slow-growing, to a maximum length of about 90 mm, and may take four years to reach maturity. It gives birth to live young. It is...
, White's Rock-skink
Lissolepis Peters, 1872 – mourning skinks
Mid-sized skinks (adult snout-vent length 100–130 mm) with a bulky angular body and small eyes. 20–28 rows of midbody scales; dorsal scales smooth. The nasal scale has a postnarial groove; the subocular scale row is complete. Eyelids similar in colour to the adjacent scales.
- Egernia coventryi (Storr, 1978) – Eastern Mourning Skink
- Egernia luctuosa (Peters, 1866) – Western Mourning Skink, Western Glossy Swamp Skink