Grismer, L. Lee

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The University of Kansas: Journals@KU

2 IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 GRISMERCat Geckos (Aeluroscalabotes felinus) are most commonly found in shrubs and low trees in the vicinity of streams. Although this is themost ancient of all living gecko lineages, these lizards bear a number of highly specialized features to accommodate their arboreallifestyle.Iguana 13.1 b&w text.QX6  3/3/06  7:15 AM  Page 2Geckos are one of the largest and most distinctive groups oflizards in the world and, in some regions, are among themost 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 sculptedpupilary margins, and adept climbers. In fact, this latter charac-teristic, accompanied by its myriad of digital specializations, isthe iconic trademark of geckos and a key feature of their overallsuccess and diversity. The vast majority of geckos have varyingdegrees of digital specializations involving the modification ofthe scales beneath their toes. These enhance their ability to gainpurchase on a wide range of substrates, be they vertical orinverted, rough or smooth. The most common specializationcomes in the form of “toe pads.” The scales on the underside ofthe digits (subdigital lamellae) have become transverselyexpanded to increase their overall surface area and are adornedwith microscopic structures that enhance adhesion to almost anysubstrate. Toe pads may occur along the entire length of thedigit, as in the majority of species, including the familiar TokayGecko (Gekko gecko) and the Common House Gecko(Hemidactylus frenatus), or they may involve only the terminalscales at the tips of the digits as in the many species of NewWorld Leaf-toed Geckos (Phyllodactylus spp.). Still others havedigits on which expanded scales occur only at the base and theremainder of the digit is slender and unmodified. In all of thesedigits, the claw may or may not be present.In the ancient, tropical lowlands of southern peninsularMalaysia and the associated islands of the Seribuat Archipelago,which is cradled along its eastern shore, geckos are not only themost diverse group of lizards, but among the most conspicuousSlender Toes in Southern MalaysiaL. Lee GrismerDepartment of Biology, La Sierra University, Riverside, CaliforniaIGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 3GECKOS OF SOUTHERN MALAYSIAMany 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.Iguana 13.1 b&w text.QX6  3/3/06  7:15 AM  Page 3nocturnal elements in these rainforest ecosystems. Although anumber 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 — onewhere the digits are kinked or bent along their length, and thesubdigital scales for the most part remain unmodified or are onlyslightly expanded at the base of the digit. This bend or inflec-tion, which can occur in geckos with toe pads as well, resultsfrom modifications in the shapes of the phalanges (the bones inthe digits) and the way they articulate with one another, result-ing in yet another adaptation for climbing. The padless geckoswith bent fingers and toes in this part of the world are the CatGecko (Aeluroscalabotes felinus), the Bent-toed Geckos(Cyrtodactylus ssp.), and the Rock Geckos (Cnemaspis spp.).Aeluroscalabotes felinus is a slow moving, catatonic speciesmost commonly found in shrubs and low trees in the vicinity ofstreams. The species’ distribution extends from southernThailand south through peninsular Malaysia and Singapore toBorneo. Although this is the most ancient of all living gecko lin-eages (Grismer, 1988), it bears a number of highly specializedfeatures to accommodate its arboreal lifestyle. These includemore forwardly directed eyes, a prehensile tail, and, of course,bent, padless digits. Additionally, digits one and two are nearlyparallel in arrangement and they oppose digits four and five,which also are parallel to one another, thus providing A. felinuswith a chameleon-like grasp of the substrates on which it climbs.The Bent-toed Geckos, genus Cyrtodactylus, comprise oneof the largest groups of geckos in the world. This genus containsat least 90 species and ranges across all of Asia and into theSouth Pacific. It also is one of the fastest growing groups, withover 15 new species being discovered and described within thelast five years. One-third of those came from southern peninsu-lar Malaysia and the Seribuat Archipelago: C. aurensis, endemicto Aur Island (Grismer 2005); C. semenanjungensis, endemic tosouthern peninsular Malaysia (Grismer and Leong 2005); C.seribuatensis, endemic to seven islands in the SeribuatArchipelago (Youmans and Grismer 2005); C. sworderi, endemicto southern peninsular Malaysia and just recently rediscoveredand redescribed (Grismer et al. 2006); and C. tiomanensis,endemic to Tioman Island (Das and Lim 2001). In addition tothese 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 climbingabilities, and each species seems content to spend the majorityof its time in one type of microhabitat. For the smaller (65–75mm SVL) Cyrtodactylus quadrivirgatus, C. semenanjungensis, andC. sworderi, this microhabitat usually consists of branches andleaves of the small trees in which they forage, and these speciesare most frequently encountered while they are precariouslyperched 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 oftheir time on tree trunks and boulders. The former two speciesare commonly seen as high as 15 m above the forest floor on thesides of trees, whereas C. aurensis is a bit more discriminating inthat it is almost exclusively found on relatively small bouldersthat are partially concealed by overhanging vegetation.The most specialized species of all the Bent-toed Geckos insouthern Malaysia is the newly discovered and describedCyrtodactylus seribuatensis of the Seribuat Archipelago. Thisremarkable endemic is restricted to the periphery of seven tinyislands, where it makes its living in the harsh, ever-changinginterface 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, fewspecies successfully exploit this microhabitat. Making a livinghere means an individual must gauge its activities around a dailycycle 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 oflizards known to live in intertidal areas and feed exclusively (ornearly so) from such a salty menu have evolved some extraordi-nary anatomical and physiological adaptations for eliminatingthe excess salt they ingest (e.g., Dunson 1976, Grismer 1994,Hazard et al. 1998). Although our studies of C. seribuatensis havejust begun, stomach content analyses and field observations con-firm it is eating intertidal invertebrates — but we do not yetknow how it deals with the excess salt load. During the day,these lizards remain hidden beneath surface debris such ascoconut 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 GRISMERAnother Bent-toed Gecko (Cyrtodactylus quadrivirgatus) is commonand ranges widely across southeastern Asia.Smaller (65–75 mm SVL) species of Bent-toed Geckos (Cyrtodactylusspp.), 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.Iguana 13.1 b&w text.QX6  3/3/06  7:15 AM  Page 4IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 5GECKOS OF SOUTHERN MALAYSIAand lizards can be seen moving about, hopping from rock torock, and foraging in the cobble at the water’s edge.The Rock Geckos (Cnemaspis spp.) of southern Malaysiaare a curious, somewhat cartoonish looking group of lizards that,as their common name would suggest, spend the vast majorityof 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 diversityis in Indochina and southeastern Asia. The digits of RockGeckos lack all traces of toe pads and, for the most part, appearcompletely 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. Thedigits are also very long, which is functionally complementaryto their very long limbs and tails and flattened heads and bod-ies. All of this serves to bring the lizard’s center of gravity closeto the substrate, which any good rock-climber will tell you, isessential to keep from falling. So, the flattened body with thelong, 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 comingfrom “above.” As such, these lizards have evolved flattened headswith widened snouts, making them somewhat duck-like inappearance, and their eyes have moved inward toward the cen-ter of the head and have rotated slightly upward, enabling themto see “up” without having to raise their heads too far off thesubstrate. Cnemaspis steps even further out of the typical geckomold 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, threeof which are some of the largest members of the group (90–100mm SVL) and endemic to their own island in the SeribuatArchipelago: C. baueri, an endemic of Aur Island (Das andGrismer 2003), C. lim, an endemic of Tioman and Tulai islands(Das and Grismer 2003), and C. pemanggilensis, which isendemic to Pemanggil Island (Grismer and Das 2005). A fourthand somewhat smaller species (C. kendallii) is widespreadthroughout Malaysia. During the day, C. baueri, C. limi, and C.pemanggilensis can be observed moving about in their bouldermicrohabitat — 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 intothe cave-like boulder piles looking for them. Cnemaspis kendal-lii, on the other hand, is commonly seen foraging on rocks andthe trunks of large trees, darting to and fro in the green filteredsunlight beneath the canopy. In fact, this species is so obvious attimes, it has evolved an anti-predator defensive display duringwhich it curls its tail high above its back, showing off the bright-yellow underside while wagging it slowly back and forth. Atnight, C. kendallii turns a ghostly white and can be found sleep-ing on rocks and the trunks of trees, or even clinging to theundersides of leaves as much as 20 m above the forest floor.Unfortunately, some of these bent-toed denizens ofMalaysia are in danger of losing major tracts of their habitat.Much of the lowland forest of southern peninsular Malaysia, towhich Cyrtodactylus sworderi and C. semenanjungensis areendemic, is being converted into oil palm plantations (think ofthis the next time you order popcorn at the movies, the yellowcoloration of which comes from palm oil). Although our dataLarger species (120–135 mm SVL) of Bent-toed Geckos (Cyrto-dactylus spp.), such as C. tiomanensis, spend most of their time on treetrunks 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 makesits living in harsh, ever-changing intertidal zones.The Rock Geckos, such as Cnemaspis lim, are a curious, somewhatcartoonish looking group of lizards that, as their common namewould suggest, spend the vast majority of their time on boulders.Iguana 13.1 b&w text.QX6  3/3/06  7:15 AM  Page 5on the natural history of these two species comes only fromanecdotal observations made during the collection of the typeseries, these geckos are clearly lowland rainforest specialists. Innearby mountainous regions, where we have been conductingfield research, we have not yet found these species and believethe habitat there is inappropriate. Nor is this habitat appropri-ate for the oil palm industry, which is rapidly replacing theextremely diverse flora and fauna of the lowland rainforests witha single species of palm. This will not only affect the species ofCyrtodactylus, but every other species in the region. Currently,these isolated mountain ranges amid a sea of oil palms are allthat is left of the native rainforest in some areas. If not for theexistence of the Endau-Rompin National Forest in this generalarea, which thus far has resisted habitat conversion and has beenhost to a number of scientific expeditions (see Wood et al. 2006for 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 endemicCnemaspis baueri, C. limi, and C. pemanggilensis enjoy the safetyof their shaded, rocky retreats. These are rapidly becoming pop-ular tourist get-aways, with all the accoutrements of a growingtourism infrastructure — and they are beginning to makeinroads into the forest. In fact, the villagers on Tioman Islandand many of Malaysia’s leading scientists and naturalist are strug-gling right now to halt the construction of a marina and a largeairport along a portion of virgin, unspoiled coastline (Grismer2005). Currently, none the species are listed on the IUCN RedList, although the endemic, insular species would clearly qualify(see http://www.redlist.org/info/categories_criteria.html).ReferencesDas, I. and L.L. Grismer. 2003. Two new species of Cnemaspis Strauch, 1887(Squamata: Gekkonidae) from the Seribuat Archipelago, Pahang andJohor 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 andW.R. Dunson (eds.), Biology of the Reptilia. Vol. 5. Physiology A.Academic Press, New York.Grismer, L.L. 1988. Phylogeny, taxonomy, classification, and biogeography ofeublepharid 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 Gulfof California. Herpetologica 50:451–474.Grismer, L.L. 2005a. A new species of Bent-toed Gecko (Cyrtodactylus Gray1827) from Pulau Aur, Johor, West Malaysia. Journal of Herpetology39:424–432.Grismer, L.L. 2005b. Tioman Archipelago, evolution’s laboratory. MalaysianNaturalist 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 Herpetology39:64–71.Grismer, L.L., P.L. Wood, Jr., and T.M. Youmans. 2006. Redescription of thegekkonid 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 byan 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, WestMalaysia. Hamadryad 30: in press.Youmans, T.M. and L.L. Grismer. 2006 (“2005”). Description of a new speciesof Cyrtodactylus (Reptilia: Squamata: Gekkonidae) from the SeribuatArchipelago, West Malaysia. Herpetological Natural History 10: in press.6 IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 GRISMERBecause many potential predators come from “above,” Rock Geckos,such as Cnemaspis baueri, have evolved flattened heads with widenedsnouts, making them somewhat duck-like in appearance, and eyesthat are rotated slightly upward, enabling them to see “up” withouthaving to raise their heads too far.At night, Cnemaspis kendallii turns a ghostly white and can be foundclinging to the undersides of leaves as much as 20 m above the forestfloor.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 worldwill speak. All proceeds from the charity banquet will be donated to the International Reptile Conservation Foundation.Iguana 13.1 b&w text.QX6  3/3/06  7:15 AM  Page 6IGUANA  •  VOLUME 13, NUMBER 1  •  MARCH 2006 7GECKOS OF SOUTHERN MALAYSIAThe geckos of southern Malaysia occur in one of the mostbiologically diverse and complex terrestrial ecosystems in theworld. Lowland rainforests are renowned for their diversity, but,in southern Malaysia, and especially on Tioman Island where 13species of geckos make their home, the diversity is even moreastounding. Tioman is the largest island in the SeribuatArchipelago 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 definemuch of the island’s rugged topography, and its hillsides are cutby a number of boulder-strewn, fast-flowing streams in bothopen and closed canopy forest. This environmental diversity sup-ports nearly 100 species of amphibians and reptiles on this smallisland. These range from tree-hole nesting and stream-dwellingfrogs such as the White-spotted Treefrog (Nyctixalus pictus) andthe Spotted Stream Frog (Rana picturata), respectively, to strangelooking lizards such as the Chameleon Anglehead Lizard(Gonocephalus chamaeleontinus). At least 44 species of snakes liveon Tioman Island, with adaptive types ranging from tiny blindsnakes in the family Typhlopidae to King Cobras (Ophiophagushannah), Red-headed Kraits (Bungarus flaviceps), and ReticulatePythons (Python reticulatus). Geckos are an intricate part of thisdiverse ecosystem and function as both predators and prey formany 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 CommunityIguana 13.1 b&w text.QX6  3/3/06  7:15 AM  Page 7

Slender Toes in Southern Malaysia

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Slender Toes in Southern Malaysia

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