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2 IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 GRISMER

Cat Geckos (Aeluroscalabotes felinus) are most commonly found in shrubs and low trees in the vicinity of streams. Although this is the
most ancient of all living gecko lineages, these lizards bear a number of highly specialized features to accommodate their arboreal
lifestyle.

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Geckos are one of the largest and most distinctive groups of
lizards in the world and, in some regions, are among the

most conspicuous elements of the ecosystem. Well over 800 cur-
rently recognized species of geckos are distributed worldwide,
with the highest concentration occurring in tropical and sub-
tropical regions. Most geckos are nocturnal, thin-skinned, large-
headed with bulging, lidless eyes boasting extravagantly sculpted
pupilary margins, and adept climbers. In fact, this latter charac-
teristic, accompanied by its myriad of digital specializations, is
the iconic trademark of geckos and a key feature of their overall
success and diversity. The vast majority of geckos have varying
degrees of digital specializations involving the modification of
the scales beneath their toes. These enhance their ability to gain
purchase on a wide range of substrates, be they vertical or
inverted, rough or smooth. The most common specialization
comes in the form of “toe pads.” The scales on the underside of

the digits (subdigital lamellae) have become transversely
expanded to increase their overall surface area and are adorned
with microscopic structures that enhance adhesion to almost any
substrate. Toe pads may occur along the entire length of the
digit, as in the majority of species, including the familiar Tokay
Gecko (Gekko gecko) and the Common House Gecko
(Hemidactylus frenatus), or they may involve only the terminal
scales at the tips of the digits as in the many species of New
World Leaf-toed Geckos (Phyllodactylus spp.). Still others have
digits on which expanded scales occur only at the base and the
remainder of the digit is slender and unmodified. In all of these
digits, the claw may or may not be present.

In the ancient, tropical lowlands of southern peninsular
Malaysia and the associated islands of the Seribuat Archipelago,
which is cradled along its eastern shore, geckos are not only the
most diverse group of lizards, but among the most conspicuous

Slender Toes in Southern Malaysia
L. Lee Grismer

Department of Biology, La Sierra University, Riverside, California

IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 3GECKOS OF SOUTHERN MALAYSIA

�

Many of the Bent-toed Geckos (Cyrtodactylus spp.) have only recently been discovered and named; the article formally describing C. aurensis,
which is endemic to Aur Island, was published in 2005.

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nocturnal elements in these rainforest ecosystems. Although a
number of the species have “typical” gekkonid fingers and toes,
on which the toe pads extend along the length of the entire digit,
the most speciose groups have a different type of digit — one
where the digits are kinked or bent along their length, and the
subdigital scales for the most part remain unmodified or are only
slightly expanded at the base of the digit. This bend or inflec-
tion, which can occur in geckos with toe pads as well, results
from modifications in the shapes of the phalanges (the bones in
the digits) and the way they articulate with one another, result-
ing in yet another adaptation for climbing. The padless geckos
with bent fingers and toes in this part of the world are the Cat
Gecko (Aeluroscalabotes felinus), the Bent-toed Geckos
(Cyrtodactylus ssp.), and the Rock Geckos (Cnemaspis spp.).

Aeluroscalabotes felinus is a slow moving, catatonic species
most commonly found in shrubs and low trees in the vicinity of
streams. The species’ distribution extends from southern
Thailand south through peninsular Malaysia and Singapore to
Borneo. Although this is the most ancient of all living gecko lin-
eages (Grismer, 1988), it bears a number of highly specialized
features to accommodate its arboreal lifestyle. These include
more forwardly directed eyes, a prehensile tail, and, of course,
bent, padless digits. Additionally, digits one and two are nearly
parallel in arrangement and they oppose digits four and five,

which also are parallel to one another, thus providing A. felinus
with a chameleon-like grasp of the substrates on which it climbs.

The Bent-toed Geckos, genus Cyrtodactylus, comprise one
of the largest groups of geckos in the world. This genus contains
at least 90 species and ranges across all of Asia and into the
South Pacific. It also is one of the fastest growing groups, with
over 15 new species being discovered and described within the
last five years. One-third of those came from southern peninsu-
lar Malaysia and the Seribuat Archipelago: C. aurensis, endemic
to Aur Island (Grismer 2005); C. semenanjungensis, endemic to
southern peninsular Malaysia (Grismer and Leong 2005); C.
seribuatensis, endemic to seven islands in the Seribuat
Archipelago (Youmans and Grismer 2005); C. sworderi, endemic
to southern peninsular Malaysia and just recently rediscovered
and redescribed (Grismer et al. 2006); and C. tiomanensis,
endemic to Tioman Island (Das and Lim 2001). In addition to
these species, the more common and widely distributed C. con-
sobrinus and C. quadrivirgatus also occur in the region.

The Bent-toed Geckos are notorious for their climbing
abilities, and each species seems content to spend the majority
of its time in one type of microhabitat. For the smaller (65–75
mm SVL) Cyrtodactylus quadrivirgatus, C. semenanjungensis, and
C. sworderi, this microhabitat usually consists of branches and
leaves of the small trees in which they forage, and these species
are most frequently encountered while they are precariously
perched at the end of some small twig or on the surface of a leaf.
The larger species (120–135 mm SVL), such as C. consobrinus,
C. tiomanensis, and, to some extent, C. aurensis, spend most of
their time on tree trunks and boulders. The former two species
are commonly seen as high as 15 m above the forest floor on the
sides of trees, whereas C. aurensis is a bit more discriminating in
that it is almost exclusively found on relatively small boulders
that are partially concealed by overhanging vegetation.

The most specialized species of all the Bent-toed Geckos in
southern Malaysia is the newly discovered and described
Cyrtodactylus seribuatensis of the Seribuat Archipelago. This
remarkable endemic is restricted to the periphery of seven tiny
islands, where it makes its living in the harsh, ever-changing
interface between land and sea known as the intertidal zone.
This is one of the most extreme environments in which a ter-
restrial vertebrate may choose to live and, not surprisingly, few
species successfully exploit this microhabitat. Making a living
here means an individual must gauge its activities around a daily
cycle of advancing and receding tides, which is further compli-
cated by the fact that each episode dramatically alters the habi-
tat. Additionally, food can be scare and what is available is usu-
ally hypersaline because of its marine origin. The handful of
lizards known to live in intertidal areas and feed exclusively (or
nearly so) from such a salty menu have evolved some extraordi-
nary anatomical and physiological adaptations for eliminating
the excess salt they ingest (e.g., Dunson 1976, Grismer 1994,
Hazard et al. 1998). Although our studies of C. seribuatensis have
just begun, stomach content analyses and field observations con-
firm it is eating intertidal invertebrates — but we do not yet
know how it deals with the excess salt load. During the day,
these lizards remain hidden beneath surface debris such as
coconut husks, palm fronds, and pieces of driftwood that accu-
mulate on the beach. At night, they emerge to search for food,

4 IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 GRISMER

Another Bent-toed Gecko (Cyrtodactylus quadrivirgatus) is common
and ranges widely across southeastern Asia.

Smaller (65–75 mm SVL) species of Bent-toed Geckos (Cyrtodactylus
spp.), such as C. sworderi, are most frequently encountered when pre-
cariously perched at the end of a small twig or on the surface of a leaf.

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IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 5GECKOS OF SOUTHERN MALAYSIA

and lizards can be seen moving about, hopping from rock to
rock, and foraging in the cobble at the water’s edge.

The Rock Geckos (Cnemaspis spp.) of southern Malaysia
are a curious, somewhat cartoonish looking group of lizards that,
as their common name would suggest, spend the vast majority
of their time on rocks — in this case, boulders. This is a rela-
tively large group of nearly 50 species dispersed to areas as dis-
tant as eastern Africa and India, although their highest diversity
is in Indochina and southeastern Asia. The digits of Rock
Geckos lack all traces of toe pads and, for the most part, appear
completely unmodified — save for that same old bend, which,
as in Cyrtodactylus, is an adaptation to its bouldering lifestyle.
This, however, is not the only specialization in this group. The
digits are also very long, which is functionally complementary
to their very long limbs and tails and flattened heads and bod-
ies. All of this serves to bring the lizard’s center of gravity close
to the substrate, which any good rock-climber will tell you, is
essential to keep from falling. So, the flattened body with the
long, splayed, limbs and elongate digits is the perfect morphol-
ogy for moving about on vertical and inverted flat surfaces.
Attendant with this lifestyle and microhabitat preference, how-
ever, is the fact that many potential predators will be coming
from “above.” As such, these lizards have evolved flattened heads
with widened snouts, making them somewhat duck-like in
appearance, and their eyes have moved inward toward the cen-
ter of the head and have rotated slightly upward, enabling them
to see “up” without having to raise their heads too far off the
substrate. Cnemaspis steps even further out of the typical gecko
mold in that it does not have the weird looking eyes and elabo-
rate pupils of most species, but instead has simple, round pupils,
which, surprisingly, is in line with its other gecko-mold-break-
ing characteristic — it is diurnal.

Four species of Cnemaspis occur in southern Malaysia, three
of which are some of the largest members of the group (90–100
mm SVL) and endemic to their own island in the Seribuat
Archipelago: C. baueri, an endemic of Aur Island (Das and
Grismer 2003), C. lim, an endemic of Tioman and Tulai islands
(Das and Grismer 2003), and C. pemanggilensis, which is
endemic to Pemanggil Island (Grismer and Das 2005). A fourth
and somewhat smaller species (C. kendallii) is widespread
throughout Malaysia. During the day, C. baueri, C. limi, and C.
pemanggilensis can be observed moving about in their boulder
microhabitat — but only in dark, shady areas where one boul-
der leans against another or in the deep recesses of large cracks.
This would lead one to think that these species are nocturnal.
However, at night they are hard to find unless you go deep into
the cave-like boulder piles looking for them. Cnemaspis kendal-
lii, on the other hand, is commonly seen foraging on rocks and
the trunks of large trees, darting to and fro in the green filtered
sunlight beneath the canopy. In fact, this species is so obvious at
times, it has evolved an anti-predator defensive display during
which it curls its tail high above its back, showing off the bright-
yellow underside while wagging it slowly back and forth. At
night, C. kendallii turns a ghostly white and can be found sleep-
ing on rocks and the trunks of trees, or even clinging to the
undersides of leaves as much as 20 m above the forest floor.

Unfortunately, some of these bent-toed denizens of
Malaysia are in danger of losing major tracts of their habitat.

Much of the lowland forest of southern peninsular Malaysia, to
which Cyrtodactylus sworderi and C. semenanjungensis are
endemic, is being converted into oil palm plantations (think of
this the next time you order popcorn at the movies, the yellow
coloration of which comes from palm oil). Although our data

Larger species (120–135 mm SVL) of Bent-toed Geckos (Cyrto-
dactylus spp.), such as C. tiomanensis, spend most of their time on tree
trunks and are commonly seen as high as 15 m above the forest floor.

Cyrtodactylus seribuatensis of the Seribuat Archipelago is the most spe-
cialized of all Bent-toed Geckos. This newly discovered species makes
its living in harsh, ever-changing intertidal zones.

The Rock Geckos, such as Cnemaspis lim, are a curious, somewhat
cartoonish looking group of lizards that, as their common name
would suggest, spend the vast majority of their time on boulders.

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on the natural history of these two species comes only from
anecdotal observations made during the collection of the type
series, these geckos are clearly lowland rainforest specialists. In
nearby mountainous regions, where we have been conducting
field research, we have not yet found these species and believe
the habitat there is inappropriate. Nor is this habitat appropri-
ate for the oil palm industry, which is rapidly replacing the
extremely diverse flora and fauna of the lowland rainforests with
a single species of palm. This will not only affect the species of
Cyrtodactylus, but every other species in the region. Currently,
these isolated mountain ranges amid a sea of oil palms are all

that is left of the native rainforest in some areas. If not for the
existence of the Endau-Rompin National Forest in this general
area, which thus far has resisted habitat conversion and has been
host to a number of scientific expeditions (see Wood et al. 2006
for summary), our knowledge of the natural history of this por-
tion of southern peninsular Malaysia would be all but lost.

Equally bleak is the future of the islands on which endemic
Cnemaspis baueri, C. limi, and C. pemanggilensis enjoy the safety
of their shaded, rocky retreats. These are rapidly becoming pop-
ular tourist get-aways, with all the accoutrements of a growing
tourism infrastructure — and they are beginning to make
inroads into the forest. In fact, the villagers on Tioman Island
and many of Malaysia’s leading scientists and naturalist are strug-
gling right now to halt the construction of a marina and a large
airport along a portion of virgin, unspoiled coastline (Grismer
2005). Currently, none the species are listed on the IUCN Red
List, although the endemic, insular species would clearly qualify
(see http://www.redlist.org/info/categories_criteria.html).

References
Das, I. and L.L. Grismer. 2003. Two new species of Cnemaspis Strauch, 1887

(Squamata: Gekkonidae) from the Seribuat Archipelago, Pahang and
Johor states, West Malaysia. Herpetologica 59:546–554.

Das, I. and L.J. Lim., 2000. A new species of Cyrtodactylus (Sauria: Gekkonidae)
from Pulau Tioman, Malaysia. The Raffles Bulletin of Zoology 48:223–231.

Dunson, W.A. 1976. Salt glands in reptiles, pp. 413–445. In: A.C. Gans and
W.R. Dunson (eds.), Biology of the Reptilia. Vol. 5. Physiology A.
Academic Press, New York.

Grismer, L.L. 1988. Phylogeny, taxonomy, classification, and biogeography of
eublepharid geckos, pp. 369–469. In: R. Estes and G. Pregill (eds.),
Phylogenetic Relationships of the Lizard Families. Stanford University Press,
Stanford, California.

Grismer, L.L. 1994. Three new Side-blotched Lizards (genus Uta) from the Gulf
of California. Herpetologica 50:451–474.

Grismer, L.L. 2005a. A new species of Bent-toed Gecko (Cyrtodactylus Gray
1827) from Pulau Aur, Johor, West Malaysia. Journal of Herpetology
39:424–432.

Grismer, L.L. 2005b. Tioman Archipelago, evolution’s laboratory. Malaysian
Naturalist 59:12–23.

Grismer, L.L. and I. Das. 2006 (“2005”). A new species of Cnemaspis
(Squamata: Gekkonidae) from Pulau Pemanggil, Johor, West Malaysia.
Herpetological Natural History 10: in press.

Grismer, L.L. and T.M. Leong. 2005. A new species of Cyrtodactylus (Squamata:
Gekkonidae) from southern peninsular Malaysia. Journal of Herpetology
39:64–71.

Grismer, L.L., P.L. Wood, Jr., and T.M. Youmans. 2006. Redescription of the
gekkonid lizard Cyrtodactylus sworderi (Smith 1925) from Southern penin-
sular Malaysia. Journal of Herpetology 40: in press.

Hazard, L.C., V.H. Shoemaker, and L.L. Grismer. 1998. Salt gland secretion by
an intertidal lizard, Uta tumidarostra. Copeia 1998:231–234.

Wood, P.L., Jr., L.L. Grismer, T.M. Youmans, B.S. Jones, and B.N. Nurolhuda.
2006. Additions to the herpetofauna of Endau-Rompin, Johor, West
Malaysia. Hamadryad 30: in press.

Youmans, T.M. and L.L. Grismer. 2006 (“2005”). Description of a new species
of Cyrtodactylus (Reptilia: Squamata: Gekkonidae) from the Seribuat
Archipelago, West Malaysia. Herpetological Natural History 10: in press.

6 IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 GRISMER

Because many potential predators come from “above,” Rock Geckos,
such as Cnemaspis baueri, have evolved flattened heads with widened
snouts, making them somewhat duck-like in appearance, and eyes
that are rotated slightly upward, enabling them to see “up” without
having to raise their heads too far.

At night, Cnemaspis kendallii turns a ghostly white and can be found
clinging to the undersides of leaves as much as 20 m above the forest
floor.

The Geckophile Gathering 2006 will be held on 9–11 June 2006 in Austin, Texas (http://www.gathering.geckosunlimited.com/).
If you are a geckophile, you shouldn’t miss this exciting event. Some of the best-known gecko enthusiasts from around the world
will speak. All proceeds from the charity banquet will be donated to the International Reptile Conservation Foundation.

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IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 7GECKOS OF SOUTHERN MALAYSIA

The geckos of southern Malaysia occur in one of the most
biologically diverse and complex terrestrial ecosystems in the

world. Lowland rainforests are renowned for their diversity, but,
in southern Malaysia, and especially on Tioman Island where 13
species of geckos make their home, the diversity is even more
astounding. Tioman is the largest island in the Seribuat
Archipelago and is characterized by steep-sided mountainous ter-
rain reaching 1038 m. It supports lowland rainforest on its allu-
vial foothills and hill forest above 300 m. The coastline and low-
lying periphery are dominated by mangrove and coastal forests.
Exposed granitic outcroppings consisting of large boulders define
much of the island’s rugged topography, and its hillsides are cut
by a number of boulder-strewn, fast-flowing streams in both
open and closed canopy forest. This environmental diversity sup-
ports nearly 100 species of amphibians and reptiles on this small
island. These range from tree-hole nesting and stream-dwelling
frogs such as the White-spotted Treefrog (Nyctixalus pictus) and
the Spotted Stream Frog (Rana picturata), respectively, to strange
looking lizards such as the Chameleon Anglehead Lizard
(Gonocephalus chamaeleontinus). At least 44 species of snakes live
on Tioman Island, with adaptive types ranging from tiny blind
snakes in the family Typhlopidae to King Cobras (Ophiophagus
hannah), Red-headed Kraits (Bungarus flaviceps), and Reticulate

Pythons (Python reticulatus). Geckos are an intricate part of this
diverse ecosystem and function as both predators and prey for
many species.

Chameleon Anglehead Lizard (Gonocephalus chamaeleontinus).

White-spotted Treefrog (Nyctixalus pictus).

Spotted Stream Frog (Rana picturata).

King Cobra (Ophiophagus hannah).

Reticulate Python (Python reticulatus).

The Herpetological Community

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