Template:Short description Template:For Template:Automatic taxobox
Eurydactylodes is a small genus of geckos commonly referred to as chameleon geckos<ref name=":1" /> from the subfamily Diplodactylidae, endemic to New Caledonia and few adjacent islands.<ref name=":0">AG Kluge (1967). "Systematics, phylogeny, and zoogeography of the lizard genus Diplodactylus Gray (Gekkonidae)". Australian Journal of Zoology, 15(5), 1007–1108. {{#invoke:doi|main}}</ref> Within the Diplodactylidae, Eurydactylodes resides in the Carphodactylini tribe,<ref name=":0" /> and consists of four species. All species share similar morphology as well as lifestyle and habits.<ref name=":1">Bauer, A. M., Jackman, T., Sadlier, R. A., & Whitaker, A. H. (2009). "Review and phylogeny of the New Caledonian diplodactylid gekkotan genus Eurydactylodes Wermuth, 1965, with the description of a new species". Memoires Du Museum National d'Histoire Naturelle - Zoologia Neocaledonica 6.</ref> The first of the Eurydactylodes species to be classified, E. vieillardi, was discovered in 1869.<ref name=":0" />
SpeciesEdit
Eurydactylodes comprises four species:<ref name=":1" />
| Image | Scientific Name | Common Name | Distribution |
|---|---|---|---|
| Eurydactylodes agricolae Henkel & Böhme, 2001 | Bauer's chameleon gecko | New Caledonia | |
| Eurydactylodes occidentalis Bauer et al., 2009 | New Caledonia | ||
| Eurydactylodes symmetricus (Andersson, 1908) | symmetrical gecko | New Caledonia | |
| File:Eurydactylodes vieillardi.JPG | Eurydactylodes vieillardi (Bavay, 1869) | Vieillard's chameleon gecko, Bavay's gecko | New Caledonia |
Nota bene: A binomial authority in parentheses indicates that the species was originally described in a genus other than Eurydactylodes.
Appearance and anatomyEdit
BodyEdit
Eurydactylodes geckos are approximately 55mm in length<ref name=":4">Fauna and Flora of New Caledonia. (n.d.). Retrieved from https://endemia.nc/en/</ref> with a laterally compressed and narrow body shape,<ref name=":1" /> whom are covered in enlarged scales which are smooth and flattened along the dorsal body. These geckos are pale green in colouration yet lack peritoneal pigmentation.<ref name=":5">Bauer, A. M. (1986). Systematics, biogeography and evolutionary morphology of the carphodactylini (Reptilia: Gekkonidae) (New caledonia, Australia). ProQuest Dissertations Publishing.</ref> They also feature high, prominent spines as well as an increased amount of inscriptional ribs<ref name=":1" /> which are infrequent amongst other gekkota. On the back of the hindlimb there are loose folds of skin.<ref name=":5" /> Species of Eurydactylodes are closely related in appearance to the Rhacodactylus genus.<ref name=":0" />
HeadEdit
Their head has large and flattened anterior headshields as well as an indentation of unscaled skin between the jaw and ear opening which may be complete or partial<ref name=":4" /> – and is the primary diagnostic character used to distinguish Eurydactylodes species.<ref name=":8">Skipwith, P. L. (2011). The Phylogenetic Relationships of New Caledonian Diplodactylid Geckos with Special Emphasis on Rhacodactylus. ProQuest Dissertations Publishing.</ref> Enlarged endolymphatic sacs are located extracranially, and the tongue and mouth lining is yellow or orange.<ref name=":1" /> Premaxilla are completely paired, and the maxilla is in close contact with the frontal.<ref name=":0" /> The jugal bone is large and in contact with the gecko's infraorbital processes<ref name=":0" /> while ornamentation upon the dorsal surface of the skull is present.<ref name=":0" /> Eurydactylodes have 27 scleral ossicles present in one eyeball and nasal process which is wide, short and large.<ref name=":0" /> These geckos also have approximately 30 premaxillary and 30 dental teeth which are conical and blunt.<ref name=":5" /> Such teeth are also homodont and pleurodont and increase in size anteriorly.<ref name=":5" />
TailEdit
Eurydactylodes geckos have a long and slender tail<ref name=":0" /> – being approximately the same length as their body<ref name=":4" /> and possessing a snout-vent length of 100%<ref name=":6">Bauer, A. M. (1998). Morphology of the adhesive tail tips of carphodactyline geckos (Reptilia: Diplodactylidae). Journal of Morphology (1931), 235(1), 41–58. {{#invoke:doi|main}}</ref> - and are round in cross section.<ref name=":0" /> The tail is muscular<ref name=":6" /> and prehensile,<ref name=":0" /> aided by a subcaudal scansorial pad and adhesive subcaudal tissue with soft, long hairs.<ref name=":1" /> Covered in numerous small scales,<ref name=":4" /> the tail also has pores which are located near the anal opening and are concentrated in a large singular patch.<ref name=":0" /> A caudal glandular ability enables the serial openings in the tail to squirt a defensive secretion.<ref name=":7">Henkel, F. W., & Bohme, W. (2001). A new carphodactyline gecko of the New Caledonian genus Eurydactylodes (Sauria: Gekkonidae). Salamandra-Bonn-, 37(3), 149-156.</ref> Regenerated tails appear similar to the gecko's previous tail.<ref name=":6" />
DigitsEdit
The digits of the species within the Eurydactylodes genus are short and slender as well as dilated and strongly depressed.<ref name=":0" /> Distal phalangeal elements are neither compressed nor raised and follow gekkonid formula of 2-3-4-5-3 in hands and 2-3-4-5-4 in feet.<ref name=":0" /> All digits possess claws<ref name=":0" /> which are high at the base, compressed, robust and decurved<ref name=":5" /> and feature large, singular expanded pads underneath.<ref name=":4" /> Webbing between digits is lacking or absent completely.<ref name=":0" />
Behaviour and dietEdit
Eurydactylodes geckos are actively mobile yet slow moving<ref name=":1" /> and able to live for over a decade.<ref name=":5" /> These geckos are arboreal<ref name=":0" /> and spend little time on the ground.<ref name=":1" /> These geckos display diurnality, and choose to perch on the stalks and leaves of plants even in periods of inactivity as opposed to seeking cover.<ref name=":2">The IUCN Red List of Threatened Species. (n.d.). Retrieved from https://www.iucnredlist.org/</ref> When threatened or approached, Eurydactylodes geckos may flatten their bodies against substrate, flee, hiss, growl or croak without a physical display or bite without warning.<ref name=":5" /> All Eurydactylodes species possess a defensive mechanism present in their tail which enables them to squirt a sticky liquid when stressed.<ref name=":2" /> In accordance with gekkonidae, the genus display ability of crypsis,<ref name=":1" /> possess an ability to lick their eyeballs in order to keep them clean<ref>Holub, J. (2004). Why do snakes hiss?: and other questions about snakes, lizards, and turtles. Penguin.</ref> and are insectivores<ref name=":0" /> yet also eat worms, fruit, and flower nectar.<ref>Bauer, A. M., & Sadlier, R. A. (1994). Diet of the new Caledonian gecko Rhacodactylus auriculatus (Squamata, Gekkonidae). Russian Journal of Herpetology, 1(2), 108-113.</ref>
HabitatEdit
This genus of geckos inhabits a variety of woodland environments including Maquis shrublands, sclerophyll forest, gallery forest and montane forest.<ref name=":2" /> Such forests are humid with a tropical/subtropical climate,<ref name=":2" /> with both high and low rainfall,<ref name=":5" /> and offer opportunity for the arboreal geckos to perch on plants<ref name=":7" /> including trees, shrubs, vines, sedges, grasses and ferns.<ref name=":1" /> All geckos within the genus have been recorded at 20 metres above sea level, and have an upper elevation limit of approximately 1000 metres above sea level except for E. occidentalis with an upper limit of 20 metres.<ref name=":2" />
ReproductionEdit
Eurydactylodes geckos are oviparous,<ref name=":0" /> and only breed once a year.<ref name=":5" /> They lay a hard and mostly impermeable shelled egg which is composed of calcium carbonate.<ref name=":9">Glasby, C. J., Ross, G., & Beesley, P. (Eds.). (1993). Fauna of Australia (Vol. 2A). Canberra, Australia: Canberra: AGPS.</ref> These eggs are among the largest relative to female body size of any gecko.<ref name=":8" /> Such eggs are initially pliable yet harden on exposure to air,<ref name=":9" /> and are more elongated<ref>Kratochvíl, L., & Frynta, D. (2006). Egg shape and size allometry in geckos (Squamata: Gekkota), lizards with contrasting eggshell structure: why lay spherical eggs? Journal of Zoological Systematics and Evolutionary Research, 44(3), 217–222. {{#invoke:doi|main}}</ref> and elliptical in shape in comparison to other gekkonine subfamilies.<ref name=":9" /> Enlarged endolymphatic sacs along each side of the neck are postulated to act as reservoirs storing calcareous material aiding in egg shell formation<ref name=":5" /> – being larger in females and increasing in size and density prior to egg-laying.<ref name=":9" /> However, endolymphatic sacs may also be required for assistance with periods of rapid bone growth.<ref name=":5" />
DistributionEdit
Species within the Eurydactylodes genus are endemic to New Caledonia along with few adjacent islands theorised to be due to Diplodactylinae dispersion from Southeast Asia through the Indo-Australian islands.<ref name=":0" /> E. symmetricus is located in the southern part of Grande Terre with a northernmost location of Pic Ningua.<ref name=":2" /> E. symmetricus is allopatric with E. occidentalis yet sympatric with E. vieillardi.<ref name=":2" /> E. occidentalis is present in Province Sud and distributed in the central west coast of Grande Terre between Poya and Bourail.<ref name=":2" /> E. agricolae is parapatric with E. vieillardi and dispersed amongst Province Nord within Northern Grande Terre and also on the Iles Belep and Ile Yandé.<ref name=":2" /> E. vieillardi is widespread on Grande Terre south of the Koniambo and Tchingou massifs and also located from Ile des Pins.<ref name=":2" />
EvolutionEdit
The Diplodactylidae family with which Eurydactylodes resides is postulated to have evolved from a primitive gekkonid radiation located in south-east Asian tropics within the upper Cretaceous.<ref name=":0" /> Dispersion of this ancestral stock occurred toward Australia through the Indo-Australian Archipelago.<ref name=":0" /> Within this family, the Carphodactylini tribe containing Eurydactylodes are characterised as more primitive due to presence of numerous preanal pores concentrated into a large patch as well as a large nasal process and arboreal lifestyle.<ref name=":0" /> The extensive differences between the opposing Diplodactylini tribe indicate Carphodactylini differentiation occurring as early as Palaeocene-Eocene time.<ref name=":0" /> Genera present within the New Caledonia-Loyalty Islands radiation as a result of evolutionary migration include Eurydactylodes, Rhacodactylus, and likely Bavayia.<ref name=":0" /> Eurydactylodes are convergent with Australian diplodactylid genus Strophurus, twig anoles and other gekkonids according to traits involving crypsis, defense, and reproduction.<ref name=":1" />
HistoryEdit
French herpetologist Arthur René Jean Baptiste Bavay described the species E. vieillardi under the name of Platydactylus vieillardi in his first catalogue of reptiles in New Caledonia titled Catalogue des reptiles de la Nouvelle-Caledonia et description dupuces nouvelle during 1869.<ref>Beolens, B., Grayson, M., & Watkins, M. (2011). The eponym dictionary of reptiles . Baltimore: Johns Hopkins University Press.</ref> The genus Eurydactylus was named by Henri Émile Sauvage to accommodate the new specimen described by Bavay.<ref name=":1" /> Swedish herpetologist Lars Gabriel Andersson described a second species associated with the Eurydactylus genus named E. symmetricus in the article Two new Lizards (Eurydactylus and Lygosoma) from New Caledonia according to a single specimen and without specific locality data.<ref>Andersson, L. G. (1908). Two new lizards (Eurydactylus and Lygosoma) from New Caledonia. Arkiv För Zoologi / Utgivet Af K. Svenska Vetenskaps-Akademien., 4, 1–5.</ref> The systematic placement of the genus was previously unknown until the efforts of Garth Leon Underwood who allocated the genus into the Gekkoninae according available literature in 1954.<ref name=":1" /> Underwood then proceeded to transfer the genus to the Diplodactylinae as justified by several characteristics in 1955 which has since been accepted by all following authors.<ref name=":1" /> In 1965, Heinz Fritz Wermuth altered the genus name to Eurydactylodes upon discovering that Andersson's name was a homonym for Eurydactylus LaFerté-Sénectère – an insect and member of Carabidae.<ref name=":1" /> Recently, German herpetologist Wolfgang Böhme and Friedrich Wilhelm Henkel described a third species E. agricolae in 2001 and suggested that further species may be discovered under the genus.<ref name=":7" /> D. Han reevaluated the higher order relationships of gekkotans and hence reallocated Eurydactylodes to the Family Diplodactylidae in 2004.<ref name=":1" /> An additional species E. occidentalis was also described by American herpetologists Aaron Matthew Bauer and Todd R Jackman as well as Ross Allen Sadlier and Anthony Hume Whitaker in 2009.<ref name=":1" />
ThreatsEdit
Eurydactylodes species range from CR (critically endangered) to NT (Near threatened) referring to the IUCN red list of threatened species.<ref name=":2" /> The following threats are common causations for the decreasing population trend<ref name=":2" /> of all species within the Eurydactylodes genus:
Habitat loss and deforestationEdit
Eurydactylodes habitat loss is worsened through urban development and natural disasters. Expansion of massif nickel mining in Poum, Dôme de Tiébaghi, Kaala and Taom are resulting in the destruction of Maquis vegetation.<ref name=":2" /> Livestock and wild ungulates such as deer and pigs as well as cattle at Rivière Nehoué are resultant in agricultural deforestation.<ref name=":2" /> Wood and pulp plantations and also non-timber crops require cleared land to be farmed. Wildfires occur throughout the dry forest environment along the western coast of New Caledonia and in adjacent islands.<ref name=":2" /> Southern New Caledonia is subject to the threat of indigenous forestation being transformed into exotic forestry.<ref name=":2" /> Tourism development at Gouara-Déva requires land for development causing further habitat loss.<ref name=":2" />
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Invasive speciesEdit
Predation by introduced species along the sclerophyll remnants of the western coast of New Caledonia including rodents and feral cats<ref name=":2" /> are harmful to Eurydactylodes geckos. Lower- elevation forests are abundant in the invasive ant Wasmannia auropumctata which are speculated to have a damaging effect on Eurydactylodes populations.<ref>Jourdan, H., Sadlier, R.A. and Bauer, A.M. 2001. Little Fire Ant Invasion (Wasmannia auropunctata) as a Threat to New Caledonian Lizards: Evidences from a Sclerophyll Forest (Hymenoptera: Formicidae). Sociobiology 38(3A): 283-301.</ref>
Pet tradeEdit
The resemblance of Eurydactylodes geckos to chameleons as well as its diurnal activity makes them a suitable pet for many. Thus, these geckos have been in the international pet trade since at least 2017<ref name=":3">Altherr, S., & Lameter, K. (2020). "The Rush for the Rare: Reptiles and Amphibians in the European Pet Trade". Animals (Basel), 10(11), 2085–. {{#invoke:doi|main}}</ref> as well as a potential target for illegal collection and trafficking.<ref name=":2" /> Eurydactylodes specimens have appeared on the market in Europe for 1000 Euro in 2019, and prices have reached up to US$2300 for pairs.<ref name=":3" />
ConservationEdit
All species under the Eurydactylodes genus are protected in Province Nord under Code de l'environnement de la Province Nord (Délibération No. 306-2008/APN, 24 October 2008) as well as in Province Sud under Code de l'environnement de la Province Sud (Délibération No. 25-2009/APS, 20 March 2009).<ref name=":2" /> The geckos are present in many reserves throughout southern New Caledonia, including Pic Ningua, Pic du Grand Kaori and Forêt Nord as well as Parc Provincial de la Rivière Bleue.<ref name=":2" /> No other conservation effort is enacted to preserve Eurydactylodes geckos in New Caledonia.<ref name=":2" /> It has been suggested that management of protected areas be undertaken urgently including surveys monitoring Eurydactylodes population size and trends, habitat loss and invasive fire ants.<ref name=":2" />
ReferencesEdit
Further readingEdit
- Andersson LG (1908). "Two new Lizards (Eurydactylus and Lygosoma) from New Caledonia". Arkiv för Zoologi, Utgifvet af K. Svenska Vetenskapsakademien i Stockholm 4 (14): 1–5. (Eurydactylus symmetricus, new species, pp. 1–4, Figures 1a–1d).
- Bauer AM, Jackman TR, Sadlier RA, Whitaker AH (2009). "Review and phylogeny of the New Caledonian diplodactylid gekkotan genus Eurydactylodes Wermuth, 1965, with the description of a new species". Mémoires du Muséum national d'Histoire naturelle 198: 13–36. (Eurydactylodes occidentalis, new species).
- Bavay A (1869). "Catalogue des Reptiles de la Nouvelle-Calédonie et description d'espèces nouvelles ". Mémoires de la Société Linnéenne de Normandie 15: 1-37. (Platydactylus vieillardi, new species, p. 10). (in French).
- Böhme W, Serig M (1997). "Tail squirting in Eurydactylodes: Independent evolution of caudal defensive glands in a diplodactyline gecko (Reptilia, Gekkoninae)". Zoologischer Anzeiger 235: 225–229.
- Henkel FW, Böhme W (2001). "A new carphodactyline gecko of the New Caledonian genus Eurydactylodes (Sauria: Gekkonidae)". Salamandra 37 (3): 149–156. (Eurydactylodes agricolae, new species).
- Wermuth H (1965). "Liste der rezenten Amphibien und Reptilien, Gekkonidae, Pygopodidae, Xantusiidae ". Das Tierreich 80: i-xxii + 1–246. (Eurydactylodes, new genus, p. 30). (In German.)