Order Squamata
Suborder Scincomorph
Family Scincidae (Skinks)
The family Scincidae is the most species-rich lizard family with
about 1200 species. Many species-rich genera (e.g. Sphenomorphus,
Mabuya) are still studied insufficiently and their systematics is
controversial.
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Appearance:
Typically scincids are slighly to
markedly elongate lizards that have relatively long-snouted
and somewhat flattened skulls, in which the upper temporal
opening is usually reduced or lost. The head is usually
covered with enlarged plates, termed head shields, and
osteoderms are frequently present in some or all scales.
These osteoderms are unusual because each is composed
of a set of smaller ones in contrast to a single bone as in
other lizards. Smooth, shiny cycloid scales (few exceptions,
e.g. members of the genus Tribolonotus).
The partially to well-developed
secondary palate is a distinctive feature of the
skull. It is formed primarily
by development of a novel lamina of the palatine bone on
each side, which together essentially floor and prolong the
choanal passage. In some species the palatal rami of the
pterygoids extend the secondary palate posteriorly to about
the level of the back of the tongue. Other osteological
characteristics include paired premaxillae, descending
processes from the parietals which meet the epipterygoids
and an enlarged coronoid process of the dentary. The inner
ear has an accessory inertial body, the culmen, which
modulates hair cell sensitivity, and largely replaces the
tectorial membrane, which is vestigial in skinks. Preanal
and femoral pores are absent.
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Limb loss: Several lineages of
skinks have lost their limbs completely (e.g.
Brachymeles, Isopachys,
Typhlosaurus, Acontias). A few
genera have species with various degrees of limb loss (e.g.
Lerista and Chalcides, see Greer 1987).
The tail is usually long and tapering and,
except for a very few species, can be shed and regenerated. The
tongue is broad, has an arrowhead-shaped tip and is covered with
serrated scales. Limb reduction in some form has occurred more than
30 times within skinks (Greer, 1991). Several authors have argued
that there may have been a reversal of limb loss in a few lineages of
skinks but this has not been demonstrated convincingly (see
discussion in Greer 1991 and Ehiting et al. 2003).
Zoological definition:
(1) ossifications present in eyelids; (2)
osteoderms present dorsally, ventrally, and on head; (3) upper arcade
complete or nearly, with jugal and squamosal near or in contact; (4)
upper temporal fossa roofed over, mainly by postfrontal; (5) no
femoral or pre-anal pores; (6) dorsal scales flat and
imbricate
Distribution: Worldwide
Habitat: Terrestrial and
fossorial species are more prevalent than arboreal (e.g.
Corucia) or aquatic species (e.g.
Tropidophorus, Amphiglossus
astrolabi). Many species in desert regions are sand swimmers.
divergent paths.W hereas Ctenotus is primarily heliothermic (except
for C. pantherinus) and surface dwelling (Greer, 1989), Lerista is
primarily a fossorial group with the majority of the species
exhibiting some level of limb reduction (Greer, 1987, 1990).
Size: Small- to moderate-sized
(approximately 80% are 30-120 mm SVL maximum). A few skinks are
larger, for example, Tiliqua is 9&emdash;31 cm SVL and
Corucia is 35 cm SVL.
Food: Usually carnivorous.
Behaviour: Mostly diurnal;
some are nocturnal or crepuscular. Egernia is the most
sociable lizard known: 23 of the 31 species in the genus live in some
form of family group (O'Connor & Shine 2003: Mol. Ecol. 12: 743,
Chapple 2003 Herp. Monogr. 17: 145).
Reproduction: About 45% of
skinks are viviparous. Eggs are laid as single clutches (guarded or
abandoned) or, infrequently, communally. Clutch size is commonly low
(~ six) and is limited to one or two eggs in some species groups
(e.g., Tribolonotus and Emoia,
respectively).
Taxonomic notes:
Mittleman (1952) recognized the following lygosome genera:
Ablepharus, Anotis (= Nannoscincus), Ateuchosaurus, Carlia,
Cophoscincopus, (Cophoscincus (=Lipinia, Calyptotis and
Cophoscincopus, Cryptoblepharus, Dasia, Emoia, Eugongylus, Eumecia,
Hemiergis, Lampropholis, Leiolopisma, Leptosiaphos, Lipinia,
Lygosoma, Mochlus, Nodorha (= Lerista), Norbea (=Tropidophorus),
Ophioscincus, Otosaurus (=Sphenomorphus), Panaspis, Rhodona (=
Lerista), Riopa, Ristella, Saiphos, Scincella, Sphenomorphus,
Squamicilia (= Lygosoma), Tachygyia, Tribolonotus,
Tropidophorus.
Greer (1970) suggested 4 subfamilies for the skinks, the
Scincinae, Lygosominae, Acontinae, and Feylininae. However, they have
not been accepted universally. For example, there is no strong
support for the monophyly of the subfamilies Lygosominae and
Scincinae, but sub-Saharan African scincines + Feylinia
form a well supported monophyletic group (Whiting et al. 2003).
The Acontinae contains 3 genera (including
Acontias and Typhlosaurus).
GRIFFITH et al. (2000) suggested to erect separate subfamilies,
Eumecinae (for the 39 species of the genus
Eumeces) and Scincinae (for the 3 species of the
genus Mesoscincus). Note that these authors also
separated some species previously associated with
Eumeces in the genera Eurylepis (E.
poonaensis, E.taeniolatus), Novoeumeces (N.
indothalensis, N. schneiderii), Scincopus (S.
fasciatus), and Scincus (S. scincus, S.
mitranus, S. hemiprichii).
Trachydosaurus has been synonymized with
Tiliqua.
Neoseps has been synonymized with
Eumeces (Pariocela) by SCHMITZ et al. 2004.
List of genera:
Acontinae
Brandley et al . (2005) suggests that both Acontias and
Typhlosaurus are paraphyletic, with Acontophiops lineatus nested
within Acontias. In contrast to Brandley et al., Daniels et al.
(2006) found that Typhlosaurus is monophyletic but suggested to erect
a new genus, Microacontias, in order to avoid paraphyly within
Acontias. These authors also showed that the character used to define
Acontias (the moveable lower eyelid) is a symplesiomorphic feature,
precluding its utility as a diagnostic generic character. Within
Typhlosaurus, the characters used in its diagnosis (a head shield
that covers their eyes and a well-defined enlarged rostral area) have
evolved once, while the moveable lower eyelid in Acontias has evolved
independently at least twice (or once and lost once). Note that the
two studies used different species samples and thus require further
investigations for definitve conclusions.
Acontophiops can be distinguished from Acontias (clade 2) by
possessing two supraciliaries and with the external ear openings
hidden, while Acontias possesses three to four supraciliaries and no
external ear openings.
Click
on genus to get a list of species. Use
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* The genus Mabuya has been split into several
genera (Mabuya, Euprepis, Eutropis, Chioninia) by Mausfeld et
al. (2002) and further subdivided by BAUER 2003 (who moved many
of Mausfeld's Euprepis to Trachylepis).
Eremchenko & Das (2004) proposed a new genus,
Kaestlea for several species of Scincella.
Parachalcides has been renamed Hakaria for priority reasons.
Note that Neoseps has been renamed
Plestiodon.
Phylogeny of New Caledonian and Australasian skink genera (from Smith et al. 2007).
Phylogeny based on combined, partitioned Bayesian analysis of one mitochondrial and two nuclear genes. This tree covers 33 of the 132 skink genera accepted in this database. Paraphyletic genera are shown in color.
References:
Bauer, A.M. (2003)
On the identity of Lacerta punctata Linnaeus, 1758, the
type species of the genus Euprepis Wagler, 1830, and the
generic assignment of Afro-Malagasy skinks.
Afr. J. Herpetol. 52:1-7.
BRANDLEY, MATTHEW C.; ANDREAS SCHMITZ AND TOD W. REEDER (2005)
Partitioned Bayesian Analyses, Partition Choice, and the
Phylogenetic Relationships of Scincid Lizards.
Syst. Biol. 54 (3):1-18
Census
of Australian Vertebrate Species (CAVS) - Version 8.1 -
reptiles
Daniels, Savel R.; Neil J. L. Heideman, Martin G. J. Hendricks,
Keith A. Crandall (2006)
Taxonomic subdivisions within the fossorial skink subfamily Acontinae
(Squamata: Scincidae) reconsidered: a multilocus perspective.
Zoologica Scripta 35 (4): 353
Eremchenko, V. K & I. Das (2004)
Kaestlea: a new genus of scincid lizards (Scincidae:
Lygosominae) from the Western Ghats, south-western India.
Hamadryad, 28(1&2): 43-50.
Greer, Allen E. (1970)
A subfamilial classification of Scincid lizards.
Bulletin of the Museum of Comparative Zoology 139 (3):
151-184
Greer, Allen E. (1987)
Limb reduction in the lizard genus Lerista. 1. Variation in
the number of phalanges and presacral vertebrae.
J. Herpetol. 21 (4): 267-276
Greer, A.E. (1989) The Biology and Evolution of Australian
Lizards. Surrey Beatty and Sons, Chipping Norton.
Greer, A.E., 1990. Limb reduction in the scincid genus
Lerista.2. Variation in the bone complements of the front and rear
limbs and the number of postsacral vertebrae. J. Herpetol. 24:
142-150.
Greer, A.E., (1991)
Limb reduction in squamates: identification of the lineages and
discussion of the trends.
J. Herpetol. 25, 166-173.
Greer, A.E. & Biswas, S. (2004)
A Generic Diagnosis for the Southeast Asian Scincid Lizard Genus
Tropidophorus Duméril and Bibron, 1839 with Some
Additional Comments on Its Morphology and Distribution.
J. Herpetol. 38 (3): 426-430
Griffith, H., A. Ngo & R. W. Murphy (2000)
A cladistic evaluation of the cosmopolitan genus Eumeces
Wiegmann (Reptilia, Squamata, Scincidae).
Russ. J. Herpetol. 7 (1): 1-16
Honda, Masanao; Ota, Hidetoshi; Kobayashi, Mari;
Nabhitabhata,Jarujin; Yong, Soi-Sen & Hikida,Tsutomu (1999)
Evolution of Asian and African Lygosomine Skinks of the
Mabuya group (Reptilia: Scincidae): a molecular
perspective. Zoological Science 16: 979-984
Honda M., Ota H., Kobayashi, M.; Nabhitabhata, J.; Yong, H.-S.
& Hikida, T. (2000)
Phylogenetic relationships, character evolution, and biogeography
of the subfamily Lygosominae (Reptilia: Scincidae) inferred from
mitochondrial DNA sequences.
Mol. Phylogen. Evol. 15 (3): 452-461
Honda, M.; Ota, H.; Kohler, G.; Ineich, I.; Chirio, L.; Chen,
S.-L.; Hikida, T. (2003)
Phylogeny of the Lizard Subfamily Lygosominae (Reptilia:
Scincidae), with Special Reference to the Origin of the New World
Taxa.
Genes and Genetic Systems 78 (1): 71-80
Honda, Masanao; Ota, Hidetoshi; Murphy, Robert W.; and Hikida,
Tsutomu. (2006)
Phylogeny and biogeography of water skinks of the genus
Tropidophorus (Reptilia: Scincidae) a molecular approach.
Zoologica Scripta 35(1):85-95
Mausfeld, P.; Schmitz,A.; Böhme, W.; Misof, B.; Vrcibradic,
D.; Rocha, C.F.D. (2002)
Phylogenetic Affinities of Mabuya atlantica Schmidt, 1945,
Endemic to the Atlantic Ocean Archipelago of Fernando de Noronha
(Brazil): Necessity of Partitioning the Genus Mabuya
Fitzinger, 1826 (Scincidae: Lygosominae).
Zool. Anz. 241: 281-293
McCoy, M.
(2000)
Reptiles of the Solomon Islands.
ZooGraphics, Kuranda (Australia), CD-ROM.
Schmitz, Andreas; Patrick Mausfeld and Dirk Embert (2004)
Molecular studies on the genus Eumeces Wiegmann, 1834:
phylogenetic relationships and taxonomic implications.
Hamadryad Vol. 28 (1-2): 73-89
Smith, Sarah A.; Ross A. Sadlier, Aaron M. Bauer, Christopher C. Austin and Todd Jackman (2007)
Molecular phylogeny of the scincid lizards of New Caledonia and adjacent areas: Evidence for a single origin of the endemic skinks of Tasmantis.
Molecular Phylogenetics and Evolution 43 (3): 1151-1166
Whiting, A.S.; Aaron M. Bauer and Jack W. Sites, Jr. (2003)
Phylogenetic relationships and limb loss in sub-Saharan African
scincine lizards (Squamata: Scincidae).
Molecular Phylogenetics and Evolution 29 (3): 582-598
Zug,G.R.; Vitt, L.J. & Caldwell, J.P. (2001)
Herpetology,
2nd ed.
Academic Press San Diego, London, [...]XIV + 630 pp.
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Created: 31 Jan 1996 / Last updated: 8 July
2007