Comparative skeletal osteology of three species of Scincid lizards (Genus: Ablepharus) from Turkey

Abstract

Despite the abundance and diversity of lizards in the family Scincidae, descriptions of their cranial and postcranial osteologies are almost nonexistent. Here, we provide detailed descriptions of adult skeletal morphologies in three scincid species: Ablepharus kitaibelii, A. cher­ novi and A. budaki. The skeletal elements of these lizards are described on cleared and double-stained specimens. The general pattern of the cranial and postcranial skeletons in the three scincid species is characterized by the absence of the palatal teeth, presence of thirteen scleral ossicles in each eye, pattern of fore-hindlimb, and shape of the clavicle and interclavicle. Additionally, there are some remarkable variations regarding the number, size and position of the bones. These include the size and shape of the nasal, the degree of fusion or separation of the postfrontal and postorbital and the number of presacral vertebrae and marginal teeth.

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ISSN 1864-5755
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(2): 251 – 259
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© Senckenberg Gesellschaft für Naturforschung, 2017.
Comparative skeletal osteology of three species of
Scincid lizards (Genus: Ablepharus) from Turkey
E Yııı, Y K, K C & Ç I
Department of Biology, Faculty of Science, Dokuz Eylül University, 35160, Buca, İzmir, Turkey — Corresponding author: yildirim.elif@deu.edu.tr
Accepted 12.x.2016.
Published online at www.senckenberg.de / vertebrate-zoology on 13.x.2017.
Abstract
Despite the abundance and diversity of lizards in the family Scincidae, descriptions of their cranial and postcranial osteologies are almost
nonexistent. Here, we provide detailed descriptions of adult skeletal morphologies in three scincid species: Ablepharus kitaibelii, A. cher-
novi and A. budaki. The skeletal elements of these lizards are described on cleared and double-stained specimens. The general pattern of the
cranial and postcranial skeletons in the three scincid species is characterized by the absence of the palatal teeth, presence of thirteen scleral
ossicles in each eye, pattern of fore- hindlimb, and shape of the clavicle and interclavicle. Additionally, there are some remarkable varia-
tions regarding the number, size and position of the bones. These include the size and shape of the nasal, the degree of fusion or separation
of the postfrontal and postorbital and the number of presacral vertebrae and marginal teeth.
Key words
Scincidae, Ablepharus, Ablepharus kitaibelii, Ablepharus chernovi, Ablepharus budaki, osteology, Turkey.
Introduction
Squamata is one of the largest orders of vertebrates with
approximately 9000 recognized species. Scincidae is one
of the most abundant and diverse families with more than
1200 described species that are found in Africa, Asia,
Australia, Europe and North and South America. The ge-
nus Ablepharus is part of the Scincidae and is commonly
known as snake-eyed skink. This name is based on the
fact that they have eyelids like snakes. The Snake-eyed
Skink Ablepharus kitaibelii (BiBron & Bory, 1833), the
Chernov’s Snake-eyed Skink A. chernovi (Darevsky,
1953) and the Budak’s Snake-eyed Skink A. budaki
(Göçmen, Kumlutaş & tosunoğlu, 1996) are three out
of the ten described species of the genus Ablepharus. The
scincid lizards are mostly terrestrial and miniaturized
species with elongated bodies and short limbs (Baran &
atatür, 1998).
There are few descriptions that detail the skeletal
morphology of lizard species, despite their abundance
and diversity (Baur, 1889; Cope, 1892; arriBas, 1998,
2013; Zalusky et al., 1980; shuBin & alBerCh, 1986;
rieppel, 1992; Maisano, 2001; nanCe, 2007; Bell et al.,
2009; rosCito & roDrigues, 2010, 2012; el-Bakry et
al., 2013). However, osteological characters have provid-
ed important data for phylogenetic and functional stud-
ies (arnolD, 1983; arnolD et al., 2007; evans, 2008;
arriBas et al., 2013). Despite their systematic impor-
tance, the osteology of scincid lizards is less known than
its phylogenetic relationships. Although cranial osteol-
ogy of scincid species was covered by Caputo (2004),
saDDlier et al. (2006) and young et al. (2009), a detailed
study is lacking. Herein, we compare the adult osteology
of the three scincid species (A. kitaibelii, A. budaki and
A. chernovi) and provide detailed comparative osteologi-
cal descriptions for other scincids.

Yııı, E. et al.: Comparative skeletal osteology of three species of Ablepharus
252
Material and Methods
Twenty-eight specimens of three scincid Ablepharus
specimens were used for this study (Table 2). All speci-
mens used here were museum materials (Zoology
Department Dokuz Eylül University (ZDEU) collec-
tion of Dokuz Eylül University). Snout-vent lengths
(SVL), skull lengths and ages were measured to analyze
the relationship between age and length (Table 3). All
specimens were cleared and double stained following
the methodology of Wassersug (1976). The osteologi-
cal terminology follows Bell et al. (2003), torres-
Carvajal (2003), taraZona et al. (2008) and guerra &
Montero (2009). The cranial and postcranial characters
selected for our study follow arriBas (1998). All de-
scriptions and illustrations were made using Olympus
SZ61 Stereoscope equipped with an Olympus digital
camera. Illustrations were digitized and arranged in
CORELDRAW (Ver. X3).
Skeletochronology
Twenty-eight specimens were used for skeletochronol-
ogy of the long bones (femur or phalanges) of the limbs.
Clipped limb bones were xed in 70% alcohol, washed
in running water for 12h, decalcied in 5% nitric acid
for 2 – 3h, and rinsed overnight in distilled water. They
were dehydrated using increasing ethanol series and then
cleared in xylene. This was followed by the immersion
of the femurs in parafn for 24 h at 58°C, followed by
the embedding in parafn. Specimens were sectioned at
12 μ cross sections from the mid-diaphysis and stained in
hematoxylin for 20 min. Sections were observed under
a light microscope and the number of lines of arrested
growth (LAGs) was counted.
Results
Premaxilla. The premaxilla forms the anterior margin of
the upper jaw (Fig. 1B). Bones have an alveolar and a na-
sal process. The nasal process of the premaxilla is slender
and posterodorsally oriented between the nasals. The al-
veolar process of the premaxilla is thinner and bears teeth
along its ventral edge. The alveolar and nasal processes
of the premaxilla are similar in the three scincid species.
The premaxilla articulates with the maxillae posterolater-
ally, the vomer posteroventrally, and nasals posteriorly.
The maxillary process of the premaxilla articulates with
the premaxillary process of the maxilla.
Maxillae. The maxillae form the lateral margin of the
upper jaw (Fig. 1B). The maxillae have three processes,
a premaxillary process, an orbital process and a facial
process. The maxillary process of the premaxilla is sim-
ple in the three scincid lizards. The facial process of the
maxilla is oriented towards the nasals dorsomedially and
contacts with the prefrontals posteriorly. The orbital pro-
cess forms the posterior part of the maxilla. The bones ar-
ticulate with the premaxilla, nasals, prefrontals, lacrimals
and jugals. Ventrally, the alveolar portion of the maxilla
bears teeth.
Nasals. The nasals articulate with the premaxillae ante-
riorly, the frontal posteriorly, the maxillae anterolateally
and the prefrontals posterolaterally (Fig. 1A). The nasal
process of the premaxilla separates the nasals anterome-
dially. The shape of the nasal is different in A. budaki
compared to the other two species (A. kitaibelii and
A. chernovi). In A. kitaibelii and A. chernovi, the posteri-
or ends of the nasals are blunt and oriented to the prefron-
tals (Fig. 2B and C). In A. budaki the posterior ends of
the bones are rounded and overlap the frontal (Fig. 2A).
Frontal. The frontal is a single bone in the roof of the
skull (Fig. 1A). The bone articulates with the nasals an-
teriorly, the prefrontals anterolaterally, the postfrontals
posterolaterally and the parietal posteriorly. The antero-
lateral process of the frontal extends between the poste-
rior edge of the nasals and prefontals. The posterolateral
process in A. chernovi is sharp, whereas this process in
A. kitaibelii and A. budaki is rounded. In A. budaki only
the nasals cover the anteromedial margin of the frontal.
Prefrontals. The prefrontals are approximately triangu-
lar shaped in three scincid lizards (Fig. 1A). The bones
are anterior to the orbital cavity. The anterior process is
broad and extends to the angle formed by the facial pro-
cess of the maxilla, nasal and anterolateral process of the
frontal. The posterodorsal process is slender and elon-
gated and extends to the lateral margin of the frontal in
the three species.
Parietal. The parietal is a single bone at the end of the
skull (Fig. 1A). The bone has two processes: a short an-
terolateral and a long supratemporal process. The ante-
rolateral process of the parietal articulates with the post-
frontals whereas the supratemporal process is in contact
with the supratemporals. The bone articulates with the
postfrontals anterolaterally, the postorbitals laterome-
dially, the squamosals posterolaterally and the frontal
anteriorly. The posttemporal fenestra is present in all
species.
Postfrontals. The postfrontals are triradiate bones and
form the posterodorsal portion of the orbit (Fig. 1A). The
shape of the bones is similar in A. budaki and A. chernovi
(Fig. 3A and B). In dorsal view, the bones lie between the
frontal and postorbitals.
Postorbitals. These elongated bones are posterior to the
orbit and lie between the postfrontals and squamosals
(Fig. 1A). The bone in A. budaki and A. chernovi be-
comes slender and its end is a sharp-shaped. In A. kita-

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Table 3. Mean SVL (mm), SL (skull length; mm), age and marginal
teeth; PT: Premaxillary teeth, MT: Maxillary teeth, DT: Dentary in
28 specimens used in the present study.
Species Skull length SVL Age PT MT DT
A. budaki (n = 11) 6.69 34.24 4.83 8.7 14.0 17.0
A. chernovi (n = 7) 7.01 41.23 5.85 8.4 13.0 15.0
A. kitaibelii (n = 10) 6.88 40.68 5.72 8.5 13.0 15.0
belii, the postorbitals combine with the postfrontal as
a single bone whereas the postorbitals and postfrontals
seem to be two distinct bones in A. budaki and A. cher-
novi (Fig. 3).
Jugals. The jugals are approximately L-shaped bones
that enclose the orbit (Fig. 1B). The bones bear two
processes: the anterior and posterior process. There is a
small protuberance on the connection between anterior
and posterior processes of the jugal. The anterior pro-
cess articulates with the maxilla anterolaterally and ec-
topterygoid posteriorly. The posterior process is directed
towards to the postorbital.
Squamosals. The squamosals are elongated and slender
bones that lie lateral to the supratemporal fossa (Fig.
1A). In the dorsal view, the squamosals lie between the
supratemporals and quadrates. The bones articulate with
the quadrate ventrally and supratemporal laterally.
Vomer. The vomer lies between the premaxilla and pa-
la tines (Fig. 1B). The vomer is in loose contact with
the premaxillary process of the maxilla and forms the
fenestra vomeronasalis externa and exochoanalis.
Supratemporal. The supratemporal is a small and paired
bone that lies between the squamosal and the supratem-
poral process of the parietal. Ventrally, the bone is in con-
tact with the quadrate (Fig. 1A).
Palatines. The palatines are separated by the pyriform
space. Anteriorly, the bones articulate with the vomer and
maxilla via the vomerine and maxillary process, respec-
tively (Fig. 1B). Posteriorly, the pterygoid process articu-
lates with the pterygoids.
Ectopterygoids. The ectopterygoid is a small and slen-
der bone in the three scincid lizards. The ectopterygoids
have anterolateral, posterolateral and medial processes,
which articulate with the maxillae, jugals and pterygoids,
respectively (Fig. 1B).
Pterygoids. The pterygoids are not edentated bones that
occupy the posterior part of the palate (Fig. 1B). The
bones are separated by the pyriform space. The poste-
rior part of this space is formed by both the pterygoids
and parabasisphenoid. The bones bear three processes:
the palatine, transverse, and quadrate. The palatine and
transverse processes are present anteriorly, whereas the
quadrate process lies posteriorly. The palatine process ar-
ticulates with the pterygoid process of the palatine. The
transverse process articulates with the medial process of
the ectopterygoid. Posteriorly, the quadrate process ar-
ticulates with the quadrate.
Table 1. Cranial and postcranial characters in A. kitaibelii, A. budaki and A. chernovi.
Cranial characters A. budaki A. chernovi A. kitaibelii
Shape of the nasal process of the premaxilla Distal part is wider than proximal one Distal part is wider than proximal one Distal part is wider than proximal one
Shape of the posterior margin of the nasal Rounded Blunt Blunt
Fusion or separation of the postfrontal and
postorbital
Seperation Seperation Fusion
Overlap of the postorbital and the squamosal More than half of the length of the
postorbital
More than half of the length of the
postorbital
More than half of the length of the
postorbital
Postcranial characters
Small bony ribs on the third presacral vertebra Present Present Present
Ribs of the sixth presacral vertebra Small rib Small rib Small rib
Sternal-xiphisternal costal formula (3 + 2) (3 + 2) (3 + 2)
Number of the presacral vertebrae 31 ± 1 36 ± 1 36 ± 1
Number of short-ribbed posterior presacral
vertebrae
444
Shape of the sternal fontanelle Heart-shaped Heart-shaped Oval-shaped or Heart-shaped
Shape of the clavicle Closed-shaped Closed-shaped Closed-shaped
Table 2. Information on the specimens used in the present study.
Species Locality
A. kitaibelii Kalkan, Antalya
Köyceğiz, Muğla
Bergama, İzmir
Kaş, Antalya
Bala, Ankara
A. budaki Kaş, Antalya
Fethiye, Muğla
A. chernovi Between Bozkır and Hadim, Konya
Between Zeyne and Gülnar, Mersin
Between Mut and Karaman
Meke, Karapınar Konya
Pozantı, Adana

Yııı, E. et al.: Comparative skeletal osteology of three species of Ablepharus
254
Scleral ossicles. The scleral ossicles are thin plates that
overlap one another. There are thirteen scleral ossicles in
each eye of the three scincid species.
Basioccipital. The basioccipital is the posterior oor of
the braincase, whereas the supraoccipital forms the pos-
terior roof of it. It lies anterior to the occipital condyl and
posterior to the parabasisphenoid (Fig. 1B).
Parabasisphenoid. The parasphenoid and basisphenoid
form a single parabasisphenoid. The bone forms the an-
terior oor of the braincase, whereas the basioccipital
constitutes the posterior part. In the ventral aspect, the
bone lies between the pterygoid anteriorly and basi-
occipital posteriorly (Fig. 1B). The bone bears a long
cultriform process that is located at the anteromedial
part of the parabasisphenoid. The posterolateral process
overlaps the basioccipital and the basipterygoid process
articulates with the quadrate process of the pterygoid.
The anteromedial process overlaps the cultriform pro-
cess.
Supraoccipital. In the dorsal view, the supraoccipital is
located between the parietal and occipital condly (Fig.
1A). Anteriorly, the bone is separated from the posterior
margin of the parietal but it is only processus ascendes
that provide connection between the parietal and su-
praoccipital.
Prootic. The prootic forms the anterolateral part of the
braincase. Each bone possesses three processes: an alar
process, an anteroventral process and a posterodorsal
process. The alar process articulates with the supraoc-
cipital. The anteroventral process contacts the parabasi-
sphenoid anteriorly and the basioccipital ventrally (Fig.
1B).
Quadrates. The quadrates, which articulate with the low-
er jaw, occupy the posterolateral corner of the skull (Fig.
1A).
Mandible
The mandible comprises six paired elements: the dentary,
splenial, coronoid, angular, surangular and articular (Fig.
4). The bones articulate with the posterolateral margin
of the skull via the connection between the quadrate and
articular.
Dentary. The dentary is a long bone that forms the lower
jaw with other mandibular bones (Fig. 4B). The dentary
is the largest element of the jaw and it is only portion
of the lower jaw that bears teeth. The posterior margin
of the bone is in contact with the angular and splenial
ventrally and coronoid dorsally. Posteriorly, the bone ar-
ticulates with the surangular.
Splenial. The splenial is present on the ventromedial part
of the mandible (Fig. 4B). Anteriorly, the bone overlaps
the dentary. Dorsally the splenial articulates with the an-
teromedial process of the coronoid.
Coronoid. The coronoid is triangular bone that lies be-
tween the mandibular tooth row and the surangular bone
(Fig. 4A). The coronoid has a large dorsal process that
extends to the dorsal margin of the mandible. The height
of the coronoid process is nearly equal to the height of
the dentary in lateral view.
Angular. The angular is a small bone that lies at the ven-
tral portion of the mandible (Fig. 4A) and is located pos-
terior to the splenial.
Fig. 1. Skull of A. chernovi. A. Dorsal view and B. Ventral view. boc – basioccipital; ecp – ectopterygoid; f – frontal; j – jugal; m – maxilla;
n – nasal; pa – parietal; pbas – parabasisphenoid; pf – prefrontal; pl – palatine; pm – premaxilla; po – postorbital; pof – postfrontal; pro –
prootic; pt – pterygoid; q – quadrate; soc – supraoccipital; sq – squamosal; sut – supratemporal; vo – vomer. Scale bar = 2 mm.
A B

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VERTEBRATE ZOOLOGY — 67
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Surangular. The surangular is located between the coro-
noid anterodorsally and angular ventrally (Fig. 3A). The
bone is one of the largest bones of the mandible and lies
posterior to the dentary. In a dorsal-to-ventral sequence,
the bone articulates with the coronoid, dentary and an-
gular.
Articular. The articular forms the posterior end of the
man
dible (Fig. 3B). In lingual aspect, the bone is en-
closed by the angular, splenial and surangular bones. In
labial view, the bone is surrounded by the angular and
surangular.
Hyoid apparatus. The hyoid apparatus is located under
the lower jaw and consists of the basihyal and three vis-
ceral arches (Fig. 5). The glossohyal is anterior to the
basihyal that is the main body of the hyoid apparatus.
The hypohyal, which is lies at the anterolateral margin
of the basihyal, is a short visceral arch and continues
with the posterolaterally oriented ceratohyal. The sec-
ond visceral arch connects the posterolateral margin of
the basihyal and forms the rst long ceratobranchial.
The third visceral arch comprises the second cerato-
branchial that is located posterior to the basihyal. The
rst ceratobranchial is continuous with the rst epi-
branchial.
Teeth
Marginal teeth. The premaxilla, maxillae and dentaries
are dentate bones of these three scincids species. The
number of marginal teeth in the three scincid species is
given in Table 3.
Palatal teeth. There is edentate.
Axial and Appendicular skeleton
Vertebrae. There is a sexual dimorphism in terms of the
number of presacral vertebrae. In the vertebral column,
the atlas, the second and third vertebrae do not bear any
ribs. The following three and last four vertebrae have
short ribs in three scincids species. There is interspecic
variation as observed by the variation in the number of the
remaining vertebrae, which have long ribs. There are 22
(female) and 20 (male) presacral vertebrae in A. budaki,
whereas there are 27 (female) and 25 (male) in A. cher-
novi and 28 (female) and 24 (male) in A. kitaibelii,
Pectoral Girdle and Forelimb. The pectoral girdle con-
sists of a single interclavicle, paired clavicles, scapulae,
coracoids, epicoracioids and suprascapulae (Fig. 6A).
Fig. 2. Shape of the nasal. A. A. budaki, B. A. chernovi and C. A. kitaibelii. Scale bar = 2 mm.
Fig. 3. Position of the postfrontal and the postorbital. A. A. budaki, B. A. chernovi and C. A. kitaibelii. Scale bar = 1mm.
A
A B C
B C

Yııı, E. et al.: Comparative skeletal osteology of three species of Ablepharus
256
In all scincids species examined here, the interclavicle,
the clavicles, the scapulas, and the coracoids are bony
elements whereas the epicoracoids and suprascapulae in
A. chernovi are partly ossied elements. The clavicle is
closed and simple rounded shaped while the interclavicle
is cruciform in three scincids species. The lengths of the
anterior interclavicular process are shorter than the poste-
rior interclavicular process in A. budaki and A. chernovi
(Table 1).
The sternal-xiphisternal costal formula is (3 + 2),
which indicates that the three pairs of ribs attach to the
sternum and two pairs of ribs to the xiphisternum. A ster-
nal fontanella is also present in all scincids species. How-
ever, the shape of the sternal fontanella in A. kitaibelii is
mostly oval-shaped (except 4 specimens), whereas it is
heart-shaped in A. budaki and A. chernovi (Table 1).
The forelimb is composed of the humeus, radius,
ulna, metacarpals and digits (Fig. 6B). The ulna in the
forelimb is larger than the radius. The carpus is composed
of the radiale, ulnare, centrale and ve distal carpals. The
phalangeal formulae for the forelimbs is as follows; 2, 3,
4, 4, 3.
Pelvic Girdle and Hindlimb. The pelvic girdle consists
of the epipubis, pubis, ilium, hypoischium and ischium
(Fig. 7A). The single and large ischio-pubic fenestra is
surrounded by the pubis and ischium. The epipubis is the
terminal element, which occupies anterior to the pubis.
The hypoischium is not present in the three scincid spe-
cies.
The hindlimb consists of the femur, tibia, bula, met-
atarsals and digits (Fig. 7B). The tarsus comprises the
bulare, tibiale and two distal tarsals. The bulare is the
biggest element of the tarsus. The phalangeal formulae
for the hindlimbs from medial to lateral is as follows; 2,
4, 4, 3, 2.
Discussion
Despite the numbers of the scincids’ lizards, only few os-
teological studies of these species have been published
(Caputo, 2004; saDlier & Bauer, 2000). The skull is the
most important and complicated element of lizard skel-
eton because of the size, shape and position of the bones.
Osteological characters have provided important data
for phylogenetic and functional studies (arnolD, 1983;
arnolD et al., 2007; arriBas et al., 2013). The taxo-
nomic position of Ablepharus species has been discussed
by many authors. A. kitaibelii was dened by BiBron &
Bory (1833) for the rst time. Then, Mertens & Muller
(1940) and Martens & WerMuth (1960) were dened
that A. k. kitaibelii, A. k. fabichi and A. k. tzingeri were
three subspecies of A. kitabelii. In the following years,
Fuhn (1969, 1970) was described A. kitaibelii into ve
subspecies (A. k. kitaibelii, A. k. chernovi, A. k. tzingeri,
A. k. stepaneki and A. k. fabichi). Finally, Schmitler (1997)
accepted that there are three species (A. kitaibelii,
A. chernovi and A. budaki) in Turkey. Taxonomic po-
sition of three species of skinks is still discussed. It is
worth to be studied to show the existence of three species
as a conrmation to earlier external morphological study
of sChMiDtler (1997).
Osteologically, we indicated that these three scincid
species differ from one another in some aspects of their
skeletal elements. Three remarkable differences were
found among three scincid species and these are as fol-
lows: 1) the shape of the nasal, 2) the fusion/separation
of the postfrontal and postorbital, 3) the numbers of the
marginal teeth and 4) the number of the presacral ver-
tebrae. Also, the subfamily Scincinae shows some os-
teological characters (greer, 1970). These are the fused
vomer, C-shaped palatine, separated nasal, frontal and
Fig. 5. Hyoid apparatus of A. budaki. bh – basihyal; cb1 – rst ce-
ra tobranchial; cb2 – second ceratobranchial; ch – ceratohyal; eb1 –
rst epibranchial; gh – glossohyal; hh – hypohyal; Scale bar =
2 mm.
Fig. 4. A. kitaibelii. A. Labial view and B. Lingual view. Scale
bar = 2 mm.
A
B

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VERTEBRATE ZOOLOGY — 67
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premaxillae. Unlike the subfamily Scincinae, the frontal
in these three scincids is a single element of the skull.
Also, the palatine is approximately L-shaped in these
scincids. Morover, the nasals are separated by the nasal
process of the premaxilla anteriorly, whereas posterior
parts of them contact each other.
Studies of skeletal morphology of lizards are lim-
ited and the family scincidae is the least studied group
in this regard. There are some osteological studies that
are related to different lizard families such as Agamidae,
Tropiduridae, Lacertidae, Gymnophthalmidae (aBDala
et al., 1997; Bell et al., 2009; rostiCo & roDrigues,
2010; khosravani et al., 2011). But, detailed studies of
scincid osteology are limited (Caputo, 2004). Ablepharus
species share several features with each other including
the absence of the palatal teeth, presence of thirteen scle-
ral ossicles in each eye, pattern of fore- hindlimb, and
shape of the clavicle and interclavicle. These similarities
may be related to similar life habits (karDong, 2005).
The posttemporal fenestra is present in three scincids,
which shows that these species have a kinetic skull be-
cause the supraoccipital is not overlapped by the parietal
bone. It was formerly reported that it is present in min-
iaturized species (hanken & Wake, 1993). Specimens of
Ablepharus are one of the smallest lizards and some of
the heterochronic features are associated with the small
size. Miniaturazation give rise to reduced body size,
bones and energy expenditure. In addition to the suptem-
poral fenestra, the connections between the premaxillary
process of the maxilla and the maxillary process of the
premaxilla is simple in these three species.
Fusion or separation of the postfrontal and postorbital
is remarkable osteological character for the three scin-
cids. In A. kitaibelii, the postfrontal and the postorbital
bones are present as a single cranial element. It shows
that there is a fusion in this part of the skull of A. kita-
belii. But, both bones are distinct from one another in
A. budaki and A. chernovi.
The number of vertebrae is also an important ana-
tomical feature. It has interspecic and intraspecic vari-
ation within Squamata (hoFFstetter & gasC, 1969). In
our study, the numbers of the presacral vertebrae of the
Fig. 6. A. Pectoral girdle of A. chernovi and B. Forelimb of A. budaki. c – corocoid; cla – clavicle; ec – epicorocoid; hu – humerus; icl –
interclavicle; s – sternum; sc – scapula; ss – suprascapula; sf – sternal fontanella; xs – xiphisternum; Scale bar = 2 mm.
Fig. 7. A. Pelvic girdle of A.chernovi and B. Hindlimb of A. budaki. Scale bar = 2 mm.
A
A B
B

Yııı, E. et al.: Comparative skeletal osteology of three species of Ablepharus
258
three scincids differ from one another. Also, there is a
sexual variation among these species. In females, the
higher number of presacral vertebrae is associated with
the increased body length and also the shortest limb
(kaliontZopulou et al., 2007). The measures of the skulls
length, SVL and age are given in Table 3. A. chernovi
specimens are longer and get older than others (A. kitai-
belii and A. budaki). Also, ages in A. chernovi are cor-
related with their body length.
In the present study, we used skeletochronology to
determine whether any developmental changes occur
with the age or not. In our previous research, we found
that skeletal elements like the clavicle have some chang-
es with the age. The clavicle of the youngest specimens
of Eumesces schneideri pavimentatus has two fenestrae.
However, these fenestrae convert into a single one in the
oldest individuals (yilDiriM et al., 2015). We analyzed
that there are not any differences between the shape of
the skeletal elements and age.
Finally, the present study emphasizes the necessity of
this kind of osteological studies in lizards. Such studies
contribute the systematic and phylogenetic positions of
these lizards.
Conclusions
A. budaki, A. chernovi and A. kitaibelii show morphological dif-
ferences comparable to each other such as the shape of the nasals
or the fusion/separation of the postfrontals and postorbitals. These
differences among three scincid lizards provide important data for
future comparative morphological studies. Besides molecular stud-
ies, in the previous morphological studies have changed the taxo-
nomic position of some lizard species (arnolD, 1983; Fu, 1998;
arriBas et al., 2013). So, this kind of studies shed more light on the
systematic situation of these lizards.
Acknowledgements
The authors are indebted to two anonymous reviewers for their
helpful comments, and suggestions.
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