Rhacodactylus leachianus,commonlyknown as theNew Caledonian giant gecko,Leach's giant gecko,leachianus gecko,orLeachie,is the largest livingspeciesofgeckoand a member of the familyDiplodactylidae.It is native to most ofNew Caledonia.
| Rhacodactylus leachianus | |
|---|---|
| |
Scientific classification
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Infraorder: | Gekkota |
| Family: | Diplodactylidae |
| Genus: | Rhacodactylus |
| Species: | R. leachianus
|
| Binomial name | |
| Rhacodactylus leachianus (Cuvier,1829)
| |
| |
| Approximate distribution (New Caledonia, Oceania)
Range
| |
| Synonyms[2] | |
Taxonomy
editThespecific name,leachianus,is in honor of EnglishzoologistWilliam Elford Leach.[3]Historically, there have been three recognizedsubspeciesofR. leachianus(including thenominotypical subspecies):R. l. aubrianus,R. l. henkeli(first described bySeippandObstin 1994),[4]andR. l. leachianus.However, based on recent molecular data, no populations ofR. leachianusare granted subspecies status at the present time.[1][5]Instead, locality basedmorphotypesare used to distinguish populations ofR. leachianus.[6]
Description
edit
R. leachianusis the largestextantgecko in the world[7]and is considered an example ofisland gigantism.R. leachianusof theGrande Terrelocalities are capable of growing 14–17 inches (360–430 mm) long, with a weight range between 250 and 500 grams.[6]R. leachianusof the Insular localities are capable of growing 9–12 "(23–30 cm) long, and weighting between 150 and 300 grams. It has a heavy body, loose skin, and a small, stumpy tail. It is variable in color, coming in shades of mottled green, gray, and brown, sometimes with highlights of white, orange, and/or pink.[1]It was only exceed in size by the now extinctGigarcanum delcourtiknown from a single specimen 50% longer and probably several times heavier than the largestR. leachianusspecimens, which also originated from New Caledonia.[8]
Distribution and habitat
editR. leachianusis found in all of the southern and eastern portions of the main island ofNew Caledonia,as well as on several of the smaller islands in the group. Topographical and ecological differences observed at each locality may have contributed to the phenotypical and morphological differences seen inR. leachianus.The insular locality of Duu Ana is thought to no longer have an extant population ofR. Leachianus.[6]
Localities ofR. leachianus
editR. Leachianusoften show locality-specificphenotypicalcoloration, size, and morphological differences calledmorphotypes.The largest locality group ofR. leachianusare those found on the main island of New Caledonia, Grande Terre. The localities associated with Grande Terre, often referred to as the "mainland localities", include theYatelocale, theMount Khogislocale, theGorolocale, thePoindimielocale, and theMount Humboldtlocale. Early on, a typing system was created in attempt to group phenotypical traits seen on Grande Terre together. This typing system includedType A,Type B,andType CR. leachianus.However, this typing system is no longer considered an accurate means of locale identification, but is still commonly used for generalization within the pet trade.Type AR. leachianuswere those that had little to no patterning on the laterals, containing a dark, solid or webbed background coloration.Type BR. leachianuswere those that displayed lateral patterning in the form of linear blotches, or solid-colored vertical bars, commonly paired with a dark base coloration. Type BR. leachianuswere said to be the most patterned of the various types.Type CR. leachianuswere those that are slow growing, large geckos, commonly paired with light blotching and a dark base color. Type CR. leachianusare reported to grow up to 17 inches in length.[6][9]
R. leachianusare also found on the neighboring islands of Grant Terre, commonly referred to as the "insular localities". These Insular localities include theIsle of Pineslocale, theNuu Amilocale, theNuu Analocale, theDuu Analocale, theMorolocale, theBayonnaiselocale, theBrosselocale, and theCaanawalocale.[6][9]
Yate (mainland)
edit
R. leachianusfound in the Yate region are recognized as one of the largest localities, being heavy bodied, bulky animals. They often have elongated tails in comparison to most other locales. YateR. leachianuscan reach above 400 grams, and grow up to 15 inches in length. they are found to have a base coloration that can range from a dark brown to golden yellow. Dark netting or thin webbing is also commonly found accompanying the base coloration. Thin, white lines may also be present on the laterals.[9]
Mount Khogis (mainland)
editR. leachianusfound in the Mount Khogis region are also among the largest of the locales, commonly reaching over 300 grams. Mount KhogisR. leachianusdisplay base colorations that range from jet black to olive green. These individuals may possess enlarged scales that run the length of the snout ridges, which can be used as a differentiating factor for this locale. White blotches may also be present on the laterals, varying widely in size.[9]
Goro (mainland)
editR. leachianusfound in the Goro locality are a large locale, reaching up to 17 inches in length and 500 grams. GoroR. leachianusare dark in coloration, with accompanying white blotches that run vertically in rows along the lateral sides. White specking may also be present along the entire body of the individual.[9]
Poindimie (mainland)
editR. leachianusfound in the Poindimie region are often longer and leaner than other mainland localities. PoindimieR. leachianusare one of the largest localities, reaching over 400 grams. Base coloration is often variable, including greens, blacks, yellows, and browns. Little to no patterning is seen in the Poindimie locale, however, yellow or white spotting may occur with age.[9]
Mount Humboldt (mainland)
edit
R. leachianusfound in the Mount Humboldt region are large bodied, bulky individuals. Base coloration is often described as variable, ranging from blacks to browns and greens. White blotches may be present, commonly covering the laterals and occasionally on the dorsal. Mount HumboldtR. Leachianusmay reach up to 420 grams in weight.[9]
Brosse (Insular)
editR. leachianusfound on the island Brosse are often referred to as one of the larger insular forms with a robust shape. The coloration is often yellow or green, with large pink or white blotching, accompanied by black flecking. this locality may be referred to as the "striped neck" locale, due to bars that begin just after the head and continue down the neck area. Brosse LocalityR. leachianuscan weigh roughly 250g, and measure up to 10 inches in length. The island of Brosse is also referred to as "Isle D".[9]
Bayonnaise (Insular)
editR. leachianusfound on the island Bayonnaise are characterized by a yellow-green base color, often displaying banding that covers the laterals and dorsal. This banding can range from thinner blotched white band to larger pink, purple, or white bands. The Island of Bayonnaise is also known as "Isle C".[9]
Nuu Ana (Insular)
editR. leachianusfound on the island of Nuu Ana is the smallest recorded locality ofR. leachianus.Nuu Ana individuals often have shorter limbs with an overall robust appearance. The Nuu Ana locale may reach up to 9 inches in length, and remain under 200 grams. The base color can range from various shades of greenish yellow, often with large colorful blotching or barring along the entire body of the gecko. The island of Nuu Ana is also known as "Isle G".[9]
Nuu Ami (Insular)
edit
R. leachianusfound on the island of Nuu Ami are a small locale, reaching up to 200 grams. Nuu AmiR. leachianusoften display a darker gray iris in comparison to other localities. Base coloration may range from deep greens to bright yellows, commonly accompanied by white or pink blotching. Nuu Ami localityR. leachianusmay also have spots or blotching arranged in a "W" shape along the dorsal area. The island of Nuu Ami is also known as "Isle H".[9]
Duu Ana (Insular)
editR. leachianusfound on the island of Duu Ana are characterized by their dark green-brown base coloration, along with light colored barring that lines the laterals of the gecko. Barring may also be present along the dorsal. Duu AnaR. leachianusoften display morphological traits, such as larger legs in comparison to other insular localities. It is speculated that this locality may eat crabs, due to low availability of fruit matter on the island. The Duu Ana locale is thought to be extinct in the wild, though, evidence is needed. Smaller breeding populations remain in captivity. The island of Duu Ana is also known as "Isle I".[9]
Caanawa (Insular)
editR. leachianusfound on the island of Caanawa are a larger insular locality. The base coloration is often variable, ranging from browns to light green. The patterning on CaanawaR. leachianusoften display deep purple blotching or barring, with a significant amount of black peppering. The island of Caanawa is also known as "Isle K".[9]
Isle of Pines (Insular)
editR. leachianusfound on the Isle of Pines are the largest of the Insular localities, reaching up to 12 inches in length and surpassing 300 grams. The Isle of Pines locality is often characterized by large head and neck regions, with a robust appearance. Base coloration is often deep green, but also can range from brown to yellow. This is accompanied by white blotches present on the laterals and dorsal area of the gecko. The Isle of Pines can also be referred to as "Pine Island".[9]
Moro (Insular)
editR. leachianusfound on the Island of Moro is one of the largest insular localities, reaching up to 12 to 13 inches in length. The Moro locality often displays a green base color, with large pink or white blotching. The head shape for the Moro locality is large with a snout that is squared off. The island of Moro is also known as "Isle E".[9]
Biology
edit
R. leachianusis an arboreal species; it is primarily nocturnal and remains hidden in tree hollows during the day.[6]it has a diet that includes insects, spiders, small vertebrates, fruit, nectar, and sap. The most common component ofR. leachianusdiet consists of the fruit fromCassine curtipendula,a small fruit with a large seed that is often seen in fecal matter. It is speculated that the elongated snouts of mainland localityR. leachianussuggest a diet model that contains more vertebrate and insect matter than their insular locality counter-parts. Records ofcannibalismamongR. leachianushave been recorded, but this phenomenon could be attributed to territorial defense.[6]These giant geckos can climb vertically up glass surfaces. This is due to adhesive pads on their feet calledlamellae,which are made up of tiny hairs which increase friction force when applied to surfaces.[10]R. Leachianusalso possess large claws that aid in climbing as well.R. leachianusare capable of dropping their tail, a self-amputation process known asautotomy.[6]UnlikeCorrelophus cilliatus,R. leachianusare capable of tail regeneration through a process known asepimorphosis.Males and females ofR. leachianusdisplay differentiating morphological characteristics known assexual dimorphism.MaleR. leachianusdisplay a hemipenal bulge at the base of the tail, whereas females do not have this bulge.R. leachianusis observed to have temperature dependent sex determination. In captivity, eggs with a sustained incubated at 85 °F will often result in male offspring, and eggs that have a sustained incubation temperature of 72 °F (22 °C) will result in female offspring.[6]
Mating behavior and reproduction
editPopular lore within the enthusiast lay community has promoted the notion thatR. leachianusmay pairmonogamouslyin the wild and may remain compatible and establish apair-bond,which may last for a single breeding season or persist for several years. In captivity, some hobbyists have responded to this notion of pair-bonding by keeping successful pairs together until the animals display incompatibility (fighting, injury, abject sequester by conspecific), at which time the bond-broken animals are separated permanently or reintroduced to one another at a later date (or introduced to different animals) in an attempt to establish a new pair-bond. It remains unclear whether the pair-bond is a real phenomenon forR. leachianus.Reports from the expeditions of herpetoculturalists philippe De Vosjoli, Frank Fast, and Bill Love, provide multiple accounts of monogamous pair bonding activity, as investigated tree hollows often housed a single pair of leachianus that remained for several weeks. Breeding behavior involves biting and thrashing that can become violent, often accompanied with locking jaws. The popular notion is that these behaviors may serve to test for pair compatibility and physical capability of a mate. However, it remains unclear whether the level of savagery witnessed in captivity is present in the wild populations. The necessary limits of an otherwise healthy captive environment may disallow some natural thresholds required for the resolution of conflict between conspecifics (for example, the natural required distance of separation may exceed the space limits in a captive setting). In the wild, a male-female pair ofR. leachianuswill commonly reside in an otherwise unoccupied tree hollow, which the pair will defend by displaying territorial behavior, such as vocalization. Tree hollow related behavior is similar to that of hollow nesting birds. Mate identification is thought to be done through a process called scent marking.[6]Adult females ofR. leachianususually lay two eggs at a time (universal trait for all geckos), having up to 10clutchesper year.[6][11]Older females in captivity may not lay clutches in a breeding season, even when paired with a compatible male. However, older females can lay clutches over the course of their entire adult lifespan. Pair incompatibility in a previously compatible pair may occur, often indicated by aggressive territorial behavior and injury. There have been reports ofparthenogenesisin unpaired females in captivity, with some parthenogenic offspring reaching maturity with no apparent defects.[6]
Vocalization
editR. leachianushave the widest range of vocalizations of any member of thegekkonidaefamily.[6]R. leachianuscan make a loud growling noise, and local people call it "the devil in the trees".[11]This growling vocalization is speculated to be a warning call is often made in the presence of a predator or a rivalingR. leachianus.Clucking is another common vocalization, commonly associated withmate calling,often heard at night. A light whistle sound is used to display discomfort, or mild stress. Bird-like chirping is seen in the larger mainland localities, which incorporates a heightened stance and a gaping mouth for a threat display, often followed by a lunging motion.[6]
Coloration and camouflage
editMany lizards exhibit an ability to alter the hue and/or intensity of skin color (chameleons are the extreme example), and New Caledonian Geckos are no exception. This phenomenon is facilitated by pigment-containing cells calledchromatophores.This is a form ofcamouflageand can help the gecko blend into their environments.[citation needed]Various factors may contribute to this change in skin color, including the endocrine system or environmental factors such as variations in sunlight and temperature.[10]
Folklore
editSome of the indigenousKanak peopleof New Caledonia fear Leach's giant gecko. This is because of an old superstition which purports that it has the ability to cling to a person's body and pull out that person's soul.[12]
Conservation status
editPopulations of the speciesR. leachianushave likely been reduced byhabitat destructionand degradation. This process is still a threat to the species. It also faces predation byintroduced speciessuch as cats and various rodents. It is alsopoached.It can be electrocuted when it travels along power lines. This species is protected and it lives in several nature reserves.[1]
In captivity
editThe New Caledonian giant gecko is occasionally kept as a pet. Individuals in the pet trade are propagated withcaptive breeding;wild populations are protected. This species may live over 20 years in captivity,[13]with some individuals reaching up to 50 years old.Selective breedingfor the pet trade has continued to maintain pure localityR. leachianusin captivity,with the addition of localitycross-breedingto create desirablephenotypes,such as dramatic coloration, size, and structure.[13][6][9]
See also
editReferences
edit
- ^abcdSadlier, R.A.;Bauer, A.M.;Jourdan, H.;Astrongatt, S.;Deuss, M.;Duval, T.; Bourguet, E.; McCoy, S.; Bouteiller, A.; Lagrange, A. (2021)."Rhacodactylus leachianus".IUCN Red List of Threatened Species.2021:e.T176166A123252801.doi:10.2305/IUCN.UK.2021-2.RLTS.T176166A123252801.en.Retrieved18 November2021.
- ^Rhacodactylus leachianus.The Reptile Database. www.reptile-database.org.
- ^Beolens, Bo;Watkins, Michael;Grayson, Michael(2011).The Eponym Dictionary of Reptiles.Baltimore: Johns Hopkins University Press.ISBN978-1-4214-0227-7.OCLC794700413.
- ^Seipp, R.;Obst, F.J.(1994-12-21). "Beschreibung einer neuen Unterart des neukaledonischenRhacodactylus leachianusCuvier 1829. (Reptilia: Sauria: Gekkonidae) ".Senckenbergiana Biologica.74(2):205–211.
- ^Bauer, Aaron M.;Jackman, Todd R.;Sadlier, Ross A.;Whitaker, Anthony H.(2012-07-31)."Revision of the giant geckos of New Caledonia (Reptilia: Diplodactylidae:Rhacodactylus) ".Zootaxa.3404(1):1–52.doi:10.11646/zootaxa.3404.1.1.
- ^abcdefghijklmnoVosjoli, Philippe de (2021).Life of giant geckos.Frank Fast, Allen Repashy (2nd ed.). Vista, California.ISBN978-0-9912816-7-1.OCLC1284294251.
{{cite book}}:CS1 maint: location missing publisher (link) - ^Brawley, Sean; Dixon, Chris (2012). "Rainbow Island".Hollywood's South Seas and the Pacific War.Palgrave Macmillan.doi:10.1057/9781137090676.ISBN9781137090676.
- ^Heinicke, Matthew P.;Nielsen, Stuart V.;Bauer, Aaron M.; Kelly, Ryan; Geneva, Anthony J.;Daza, Juan D.;Keating, Shannon E.;Gamble, Tony(2023-06-19)."Reappraising the evolutionary history of the largest known gecko, the presumably extinctHoplodactylus delcourti,via high-throughput sequencing of archival DNA ".Scientific Reports.13(1): 9141.Bibcode:2023NatSR..13.9141H.doi:10.1038/s41598-023-35210-8.ISSN2045-2322.PMC10279644.PMID37336900.
- ^abcdefghijklmnop"Gallery – Leapin Leachies".Retrieved2023-04-07.
- ^abSian Rutland, C.; Cigler, P.; Kubale, V. (2019). "Reptilian skin and its special histological structures".Veterinary Anatomy and Physiology.doi:10.5772/intechopen.84212
- ^abRhacodactylus leachianus.Australian Reptile Park.
- ^https://www.youtube.com/watch?v=0FJNE4V7aPILEACHIANUS GECKOS IN THE WILD, PART 1! |Rhacodactylus leachianus| (New Caledonia, 2018)
- ^abGuide to the Largest Geckos in the World.Stephen Cemelli.