''Eurydactylodes'' is a small genus of geckos commonly referred to as chameleon geckos from the subfamily

Diplodactylidae The Diplodactylidae are a Family (biology), family in the suborder Gekkota (geckos), with over 150 species in 25 Genus, genera. These geckos occur in Australia, New Zealand, and New Caledonia. Diplodactylids are the most ecologically diverse and ...

, endemic to

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

and few adjacent islands.AG Kluge (1967). "Systematics, phylogeny, and zoogeography of the lizard genus Diplodactylus Gray (Gekkonidae)". ''Australian Journal of Zoology'', 15(5), 1007–1108. Within the Diplodactylidae, ''Eurydactylodes'' resides in the Carphodactylini tribe, and consists of four species. All species share similar

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

as well as lifestyle and habits.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. The first of the ''Eurydactylodes'' species to be classified, ''E. vieillardi'', was discovered in 1869.

Species

Eurydactylodes comprises four species: ''

Nota bene ( ; plural: ) is the Latin language, Latin phrase meaning ''note well''. In manuscripts, ''nota bene'' is abbreviated in upper-case as NB and N.B., and in lower-case as n.b. and nb; the editorial usages of ''nota bene'' and ''notate bene'' fi ...

'': A

binomial authority In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

in parentheses indicates that the species was originally described in a genus other than ''Eurydactylodes''.

Appearance and anatomy

Body

Eurydactylodes geckos are approximately 55mm in lengthFauna and Flora of New Caledonia. (n.d.). Retrieved from https://endemia.nc/en/ with a laterally compressed and narrow body shape, 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.Bauer, A. M. (1986). Systematics, biogeography and evolutionary morphology of the carphodactylini (Reptilia: Gekkonidae) (New caledonia, Australia). ProQuest Dissertations Publishing. They also feature high, prominent spines as well as an increased amount of inscriptional ribs which are infrequent amongst other

gekkota Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates. They range from . Geckos are unique among lizards f ...

. On the back of the hindlimb there are loose folds of skin. Species of Eurydactylodes are closely related in appearance to the

Rhacodactylus ''Rhacodactylus'' is a genus of medium to large geckos of the Family (biology), family Diplodactylidae. All species in this genus are found on the islands that make up New Caledonia. Genus characteristics include long limbs and toes with well-d ...

genus.

Head

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 – and is the primary diagnostic character used to distinguish Eurydactylodes species.Skipwith, P. L. (2011). The Phylogenetic Relationships of New Caledonian Diplodactylid Geckos with Special Emphasis on Rhacodactylus. ProQuest Dissertations Publishing. Enlarged

endolymph Endolymph is the fluid contained in the membranous labyrinth of the inner ear. The major cation in endolymph is potassium, with the values of sodium and potassium concentration in the endolymph being 0.91 mM and 154 mM, respectively. ...

atic sacs are located extracranially, and the tongue and mouth lining is yellow or orange. Premaxilla are completely paired, and the maxilla is in close contact with the frontal. The jugal bone is large and in contact with the gecko's infraorbital processes while ornamentation upon the dorsal surface of the skull is present. Eurydactylodes have 27 scleral ossicles present in one eyeball and nasal process which is wide, short and large. These geckos also have approximately 30

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

ry and 30 dental teeth which are conical and blunt. Such teeth are also homodont and

pleurodont Pleurodont is a form of tooth implantation common in reptiles of the order Squamata, as well as in at least one temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 've ...

and increase in size anteriorly.

Tail

Eurydactylodes geckos have a long and slender tail – being approximately the same length as their body and possessing a snout-vent length of 100%Bauer, A. M. (1998). Morphology of the adhesive tail tips of carphodactyline geckos (Reptilia: Diplodactylidae). Journal of Morphology (1931), 235(1), 41–58. - and are round in cross section. The tail is muscular and prehensile, aided by a subcaudal scansorial pad and adhesive subcaudal tissue with soft, long hairs. Covered in numerous small scales, the tail also has pores which are located near the anal opening and are concentrated in a large singular patch. A caudal glandular ability enables the serial openings in the tail to squirt a defensive secretion.Henkel, F. W., & Bohme, W. (2001). A new carphodactyline gecko of the New Caledonian genus Eurydactylodes (Sauria: Gekkonidae). ''Salamandra-Bonn-'', ''37''(3), 149-156. Regenerated tails appear similar to the gecko's previous tail.

Digits

The digits of the species within the Eurydactylodes genus are short and slender as well as dilated and strongly depressed. 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. All digits possess claws which are high at the base, compressed, robust and decurved and feature large, singular expanded pads underneath. Webbing between digits is lacking or absent completely.

Behaviour and diet

Eurydactylodes geckos are actively mobile yet slow moving and able to live for over a decade. These geckos are

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

and spend little time on the ground. These geckos display

diurnality Diurnality is a form of plant and ethology, animal behavior characterized by activity during daytime, with a period of sleeping or other inactivity at night. The common adjective used for daytime activity is "diurnal". The timing of activity by ...

, and choose to perch on the stalks and leaves of plants even in periods of inactivity as opposed to seeking cover.The IUCN Red List of Threatened Species. (n.d.). Retrieved from https://www.iucnredlist.org/ 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. All Eurydactylodes species possess a defensive mechanism present in their tail which enables them to squirt a sticky liquid when stressed. In accordance with gekkonidae, the genus display ability of

crypsis In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be part of a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean life ...

, possess an ability to lick their eyeballs in order to keep them clean and are

insectivore file:Common brown robberfly with prey.jpg, A Asilidae, robber fly eating a hoverfly An insectivore is a carnivore, carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the Entomophagy ...

s yet also eat worms, fruit, and flower nectar.

Habitat

This genus of geckos inhabits a variety of woodland environments including

Maquis shrubland 220px, Low maquis in Corsica 220px, High ''macchia'' in Sardinia ( , , ) or ( , ; often in Italian; , ; ; ; ) is a savanna-like shrubland biome in the Mediterranean region, typically consisting of densely growing evergreen shrubs. Maquis ...

sclerophyll Sclerophyll is a type of vegetation that is adapted to long periods of dryness and heat. The plants feature hard leaves, short Internode (botany), internodes (the distance between leaves along the stem) and leaf orientation which is parallel or ...

forest,

gallery forest A gallery forest is one formed as a corridor along rivers or wetlands, projecting into landscapes that are otherwise only sparsely treed such as savannas, grasslands, or deserts. The gallery forest maintains a more temperate microclimate above th ...

and

montane forest Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...

. Such forests are humid with a tropical/subtropical climate, with both high and low rainfall, and offer opportunity for the

geckos to perch on plants including trees, shrubs, vines, sedges, grasses and ferns. 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.

Reproduction

Eurydactylodes geckos are

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

, and only breed once a year. They lay a hard and mostly impermeable shelled egg which is composed of

calcium carbonate Calcium carbonate is a chemical compound with the chemical formula . It is a common substance found in Rock (geology), rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skel ...

.Glasby, C. J., Ross, G., & Beesley, P. (Eds.). (1993). Fauna of Australia (Vol. 2A). Canberra, Australia: Canberra: AGPS. These eggs are among the largest relative to female body size of any gecko. Such eggs are initially pliable yet harden on exposure to air, and are more elongated and elliptical in shape in comparison to other gekkonine subfamilies. Enlarged endolymphatic sacs along each side of the neck are postulated to act as reservoirs storing

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

material aiding in egg shell formation – being larger in females and increasing in size and density prior to egg-laying. However, endolymphatic sacs may also be required for assistance with periods of rapid bone growth. Carte de la Nouvelle-Caledonie

Distribution

Species within the Eurydactylodes genus are endemic to

along with few adjacent islands theorised to be due to Diplodactylinae dispersion from

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

through the Indo-Australian islands. E. symmetricus is located in the southern part of Grande Terre with a northernmost location of Pic Ningua. E. symmetricus is

allopatric Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

with E. occidentalis yet

sympatric In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...

with E. vieillardi. E. occidentalis is present in Province Sud and distributed in the central west coast of Grande Terre between Poya and

Bourail Bourail (, Ajië language, Ajië: Bu Rhaï) is a communes of France, commune in the South Province, New Caledonia, South Province of New Caledonia, an overseas territory of France in the Pacific Ocean. Geography Bourail is a rural town of Grand ...

. 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. E. vieillardi is widespread on Grande Terre south of the Koniambo and Tchingou massifs and also located from Ile des Pins.

Evolution

The

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 The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

. Dispersion of this ancestral stock occurred toward Australia through the Indo-Australian

Archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the o ...

. 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

lifestyle. The extensive differences between the opposing Diplodactylini tribe indicate Carphodactylini differentiation occurring as early as

Palaeocene The Paleocene ( ), or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''palai ...

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

time. Genera present within the

Loyalty Islands Loyalty Islands Province (, ) is one of the three top-level administrative subdivisions of New Caledonia. It encompasses the Loyalty Islands () archipelago in the Pacific Ocean, located northeast of the New Caledonian mainland of Grande Terre. ...

radiation as a result of evolutionary migration include Eurydactylodes,

, and likely

Bavayia ''Bavayia'' is a genus of lizards in the family Diplodactylidae. Species in the genus ''Bavayia'' are also known commonly as New Caledonian geckos or bavayias. The genus is native to the remote New Caledonia and Loyalty Islands. The 41 species a ...

. Eurydactylodes are convergent with Australian diplodactylid genus Strophurus, twig anoles and other gekkonids according to traits involving

, defense, and reproduction.

History

French herpetologist

Arthur René Jean Baptiste Bavay Arthur René Jean Baptiste Bavay (29 April 1840 in Lamballe – 1923) was a French pharmacist, herpetologist and malacologist. Biography Trained as a naval pharmacist, Bavay's scientific contributions included investigations involving the ...

described the species E. vieillardi under the name of Platydactylus vieillardi in his first catalogue of reptiles in

titled ''Catalogue des reptiles de la Nouvelle-Caledonia et description dupuces nouvelle'' during 1869. The genus Eurydactylus was named by

Henri Émile Sauvage Henri Émile Sauvage (22 September 1842 in Boulogne-sur-Mer – 3 January 1917 in Boulogne-sur-Mer) was a French paleontologist, ichthyologist, and Herpetology, herpetologist. He was a leading expert on Mesozoic fish and reptiles.

to accommodate the new specimen described by Bavay. Swedish herpetologist

Lars Gabriel Andersson Lars Gabriel Andersson (22 February 1868 – 13 February 1951) was a Swedish schoolteacher and herpetologist. He studied at Uppsala University and earned his PhD in 1909. During his long career he taught classes at several schools in and near Sto ...

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. 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. Underwood then proceeded to transfer the genus to the

Diplodactylinae The Diplodactylidae are a family in the suborder Gekkota (geckos), with over 150 species in 25 genera. These geckos occur in Australia, New Zealand, and New Caledonia. Diplodactylids are the most ecologically diverse and widespread family of geck ...

as justified by several characteristics in 1955 which has since been accepted by all following authors. 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 Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

and member of

Carabidae Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it is one of the 10 most species-rich animal ...

. 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. D. Han reevaluated the higher order relationships of gekkotans and hence reallocated Eurydactylodes to the Family Diplodactylidae in 2004. 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.

Threats

Eurydactylodes species range from CR (critically endangered) to NT (Near threatened) referring to the

IUCN red list of threatened species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological spe ...

. The following threats are common causations for the decreasing population trend of all species within the Eurydactylodes genus:

Habitat loss and deforestation

Eurydactylodes habitat loss is worsened through urban development and natural disasters. Expansion of

massif A massif () is a principal mountain mass, such as a compact portion of a mountain range, containing one or more summits (e.g. France's Massif Central). In mountaineering literature, ''massif'' is frequently used to denote the main mass of an ...

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

mining in

Poum The Workers' Party of Marxist Unification (, POUM; , POUM) was a Spanish communist party formed during the Second Spanish Republic, Second Republic and mainly active around the Spanish Civil War. It was formed by the fusion of the Trotskyism, Tro ...

, Dôme de Tiébaghi, Kaala and Taom are resulting in the destruction of Maquis vegetation. Livestock and wild ungulates such as deer and pigs as well as cattle at Rivière Nehoué are resultant in agricultural deforestation. 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

and in adjacent islands. Southern New Caledonia is subject to the threat of indigenous forestation being transformed into exotic forestry. Tourism development at Gouara-Déva requires land for development causing further habitat loss.

Invasive species

Predation by introduced species along the

remnants of the western coast of

including

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

s and

feral cat A feral cat or a stray cat is an unowned domestic cat (''Felis catus'') that lives outdoors and avoids human contact; it does not allow itself to be handled or touched, and usually remains hidden from humans. Feral cats may breed over dozens ...

s 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.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.

Pet trade

The resemblance of Eurydactylodes geckos to

chameleon Chameleons or chamaeleons (Family (biology), family Chamaeleonidae) are a distinctive and highly specialized clade of Old World lizards with 200 species described as of June 2015. The members of this Family (biology), family are best known for ...

s 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 2017Altherr, S., & Lameter, K. (2020). "The Rush for the Rare: Reptiles and Amphibians in the European Pet Trade". Animals (Basel), 10(11), 2085–. as well as a potential target for illegal collection and trafficking. Eurydactylodes specimens have appeared on the market in Europe for 1000 Euro in 2019, and prices have reached up to US$2300 for pairs.

Conservation

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). The geckos are present in many reserves throughout southern

, including Pic Ningua, Pic du Grand Kaori and Forêt Nord as well as Parc Provincial de la Rivière Bleue. No other conservation effort is enacted to preserve Eurydactylodes geckos in

. 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.

References

External links

* {{Taxonbar, from=Q137420 Diplodactylidae Endemic fauna of New Caledonia Lizard genera Reptile genera Geckos of New Caledonia Squamata Taxa named by Heinz Wermuth