''Rhacodactylus trachycephalus'', commonly known as the lesser rough-snouted giant gecko, dwarf rough-snouted giant gecko, or tough-snouted giant gecko, is a species of gecko

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

to two small areas of islands in New Caledonia. Its body grows to around and has a mosaic pattern with a variety of colors. '' Rhacodactylus trachyrhynchus'' is a closely related species, but ''R. trachycephalus'' is smaller and has a number of other noticeable differences. ''R. trachycephalus'' is

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...

, giving birth to only one or two young a year. Its restricted humid forest habitat is vulnerable due to multiple threats. As a result of habitat reduction, low reproduction rate and small population, it is one of the rarest geckos in the world.

Description

''R. trachycephalus'' has a body length of around and a snout-to-vent length of no more than , with its tail being roughly the same length as its body. The species' scales create a mosaic pattern, with patches of white, brown, grey, and green in various hues. Its toes are somewhat broad and it has a tail exhibiting

prehensility Prehensility is the quality of an appendage or organ that has adapted for grasping or holding. The word is derived from the Latin term ''prehendere'', meaning "to grasp". The ability to grasp is likely derived from a number of different origi ...

. ''R. trachycephalus'' is closely related to '' Rhacodactylus trachyrhynchus'', but has a number of noticeable differences. In particular, ''R. trachycephaluss body size is smaller than that of ''R. trachyrhynchus'' and it has larger eyes. In addition, ''R. trachycephalus'' has fewer scale rows on its midbody, as well as fewer scales in the area in between its eyes and nostrils; the scales that are in the eye-nostril area are also smaller than those on ''R. trachyrhynchus''. File:Rhacodactylus trachycephalus head.jpg, The head

Taxonomy

''Rhacodactylus trachycephalus'' was originally described by

George Albert Boulenger George Albert Boulenger (19 October 1858 – 23 November 1937) was a Belgian-British zoologist who described and gave scientific names to over 2,000 new animal species, chiefly fish, reptiles, and amphibians. Boulenger was also an active botan ...

in 1878. It was described as ''Chameleonurus trachycephalus'' the same year, also by Boulenger. In 2005, it was named as ''R. trachyrhynchus trachycephalus'', a subspecies of '' Rhacodactylus trachyrhynchus'', by Myers and again by Yuri Kaverkin in 2009. It was assigned to genus ''

Rhacodactylus ''Rhacodactylus'' is a genus of medium to large geckos of the 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-developed lamellae. ...

'' by

Aaron M. Bauer According to Abrahamic religions, Aaron ''′aharon'', ar, هارون, Hārūn, Greek (Septuagint): Ἀαρών; often called Aaron the priest ()., group="note" ( or ; ''’Ahărōn'') was a prophet, a high priest, and the elder brother of ...

in 2012, a treatment that produced the combination ''Rhacodactylus trachycephalus''.

Behavior

''R. trachycephalus'' is

, with it and ''R. trachyrhynchus'' being the only two species in their genus to exhibit viviparity. Viviparity in geckos is exclusive to New Zealand. ''R. trachycephalus'' generally gives birth to no more than two young per year, which is a very low rate of reproduction and partially why the species is so rare. To maintain a high level of heat and humidity, a large number of ''R. trachyrhynchus'' individuals will sometimes collect close together in shelters, a characteristic that is also exhibited by '' Underwoodisaurus milii''. ''R. trachyrnhynchus'' individuals sleep in tree holes with their family.

Distribution and conservation

''R. trachycephalus'' is a rare species, living exclusively in New Caledonia. The species' range is extremely restricted; it only occurs on a small area of Isle of Pines and a small island off its shore, in humid forest habitats. The offshore island is small enough that its population could be completely destroyed in the event of a single disaster and both of these populations are extremely vulnerable. ''R. trachycephalus'' is listed as Critically Endangered on the

IUCN Red List 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 the world's most comprehensive inventory of the global conservation status of biol ...

and ''Endemia.nc'', and it is protected in the Northern Province. The organism is threatened by illegal trade and fragmentation of habitat. Another factor is the infestation of the invasive little fire ant, which causes the offshore island populations to be especially at risk. It is also threatened by cats and rats, which prey on eggs, young, and adults; these invasive species, like the little fire ant, especially threaten the offshore island populations. These factors make it one of the most uncommon geckos alive currently, and possibly the rarest in the world.

References

{{Taxonbar, from=Q3429034 Rhacodactylus Reptiles described in 1878 Taxa named by George Albert Boulenger Geckos of New Caledonia Endemic fauna of New Caledonia