| Crenadactylus | |
|---|---|
 | |
| Crenadactylus ocellatus | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Family: | Diplodactylidae |
| Genus: | Crenadactylus Dixon & Kluge, 1964 [1] |
Crenadactylus, the clawless geckos, are named for their distinguishing feature, the absence of terminal claws on the digits. They are the only Australian members of Diplodactylidae to lack claws, the endemic genus is also the smallest in size.
Smaller geckos found in central and western Australia, the smallest of the Gekkota species found on the continent and notable for the absence of claws at the end of any the toes. [2] An early osteological comparison to related taxa presented considerable and unusual variation, such as being clawless, but in particular the forked arrangement of phalangeal bones within the digits of the gecko. [1] A genus, sometimes assigned to the Diplodactylidae family, whose tiny and superficially similar species have diverged in isolation at a range of habitats across a wide geographic area.
The genus has been placed with the Diplodactylidae, a family allied to the Gekkota (geckos and limbless lizard species). This is a list of species recognised at the Australian Faunal Directory, the IUCN and elsewhere, [3] [4]
Crenadactylus was erected in 1964 by the authors James R. Dixon and Arnold G. Kluge to separate the taxon described by John Edward Gray as Diplodactylus ocellatus in 1845 and referred to as a species of Phyllodactylus , the combination published by Boulenger. The authors identified the most remarkable characteristic of the new genus, the unique morphology of the phalange structures at the end of the digits. [1] These later authors noted Gray's description of Diplodactylus bilineatus, [5] specimens he had separated from the type at the British Museum, and placed this in synonymy with the name Gray had published just a few lines before. Another description published by Lucas and Frost, Ebenavia horni, was also referred to Dixon and Kluge's monotypic genus. [1] [2] In describing the new genus, Gray's note on the source of the holotype as "W. Australia" (Western Australia) could not be refined, so this was restricted to a nominated type locality at Darlington, Western Australia, inferred by comparison to specimens found at that location. [1]
Consideration of Crenadactylus as a single species, Crenadactylus ocellatus, was also recognised by various authorities as three to four subspecies. [3] [6] However, molecular evidence revealed the phylogeny of the genus indicated numerous 'hidden species', and a revision in 2016 of accepted and new descriptions recognised a total of seven species.
A molecular analysis of northern populations in 2012 examined the reported ancient divergence and up to ten lineages in northwestern Crenadactylus, with indication of geographical ranges restricted to less than 100 km2. [7] The study examined the conclusions of testing for cryptic species, published in 2010, within the poorly understood and rare populations of a purportedly monotypic species. The authors of the 2010 research had sought to test the ability of a genetic study to reveal hidden taxa, with implications for research and conservation of diversity, and the conclusion in this example was number of definable species was grossly underestimated; the authors comment on their surprise at the number of potential species discovered within a 'developed country'. [8] The phylogenetic evidence supported the proposed divergence of populations during the Oligocene-Miocene period (circa 20–30 mya). [8] A revision in 2016 of the genus, using genotyped specimens for a morphological study, elevated previous descriptions to the rank of species and published three new descriptions. [2] The conclusion of the molecular and morphological revision acknowledged greater divergence within the group, and distinguishable species that have persisted in locations for millions of years.
Prior to the reclassification of the Crenadactylus species, the population was recognised as occurring in a large distribution range that covered most of the western and central regions of Australia. The various species are found in habitat that includes the leaf-layer at the floor of woodlands, underneath rocks, in hummocks of Trioda vegetation in spinifex country, under logs and other dead woody litter, and beneath the rubbish piles introduced to their environment by human activity. [6]
The newly described species were sometime recognised as occurring in restricted ranges, becoming isolated and specialised within particular environments. The small size is a limiting factor to the species ability to move beyond the local ecology, but may have allowed them to persist in the environment with less vulnerability to the continent's climatic changes. [2]
Crenadactylus ocellatus, also known as the southwestern clawless gecko or western clawless gecko, is the smallest species of nocturnal Gecko found in Australia.
Diplodactylus is a genus of geckos of the family Diplodactylidae from Australia. They are sometimes called stone geckos or fat-tailed geckos. Member species are morphologically similar but genetically distinct.
Oedura is a genus of medium to large geckos, lizards in the family Diplodactylidae. The genus is endemic to Australia. Species in the genus are referred to by the common name velvet geckos.
The western beaked gecko is a species of gecko found throughout the interior of Australia.
The Carphodactylidae, informally known as the southern padless geckos, are a family of geckos, lizards in the infraorder Gekkota. The family consists of 32 described species in 7 genera, all of which are endemic to Australia. They belong to the superfamily Pygopodoidea, an ancient group of east Gondwanan geckos now only found in Australasia. Despite their well-developed limbs, molecular phylogenies have demonstrated that Carphodactylidae is the sister group to Pygopodidae, a highly specialized family of legless lizards.
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 geckos in both Australia and New Caledonia, and are the only family of geckos found in New Zealand. Three diplodactylid genera have recently been split into multiple new genera.
Arnold G. Kluge is professor emeritus of zoology and curator emeritus of amphibians and reptiles at the University of Michigan, Museum of Zoology.
Lucasium byrnei, also known commonly as the gibber gecko, Byrne's gecko, and the pink-blotched gecko, is a species of small, nocturnal lizard in the family Diplodactylidae. The species is endemic to Australia.
Lucasium stenodactylum, also known as the crowned gecko or pale-snouted ground gecko, is a species of gecko from Australia.
Nephrurus sheai, also known commonly as the Kimberley rough knob-tailed gecko and the northern knob-tailed gecko, is a species of lizard in the family Carphodactylidae. The species is endemic to Australia.
Diplodactylus fulleri, sometimes called the Lake Disappointment ground gecko, is a species of gecko, a lizard in the family Diplodactylidae. The species is endemic to Australia.
Main's ground gecko is a species of gecko, a lizard in the family Diplodactylidae. The species is endemic to Australia.
The Pilbara ground gecko also known commonly as Wombey's gecko, is a species of lizard in the family Diplodactylidae. The species is endemic to Australia.
The short-tailed striped gecko, also known commonly as McMillan's spiny-tailed gecko, is a species of lizard in the family Diplodactylidae. The species is endemic to Australia.
The Exmouth spiny-tailed gecko, also known commonly as Rankin's spiny-tailed gecko, is a species of lizard in the family Diplodactylidae. The species is endemic to Western Australia.
The Mount Augustus spiny-tailed gecko, also known commonly as the Mount Augustus striped gecko and Wilson's spiny-tailed gecko, is a species of lizard in the family Diplodactylidae. The species is endemic to Australia.
Pygopodoidea is a gecko superfamily and the only taxon in the gekkotan subclade Pygopodomorpha. The clade includes three Australasian families: Diplodactylidae, Carphodactylidae, and Pygopodidae. Traditional gekkotan systematics had considered Diplodactylidae and Carphodactylidae as subfamilies of the family Gekkonidae, but recent molecular work have placed Pygopodidae within Gekkonidae making it paraphyletic. These analyses have shown support of Pygopodidae and Carphodactylidae being sister taxa, with Diplodactylidae occupying a basal position in Pygopodoidea.
Crenadactylus horni, the Central Uplands clawless gecko, is a species of gecko endemic to the central desert region of Australia.
Crenadactylus occidentalis, also called the western clawless gecko, is a species of gecko endemic to the western coast of Australia.
Crenadactylus pilbarensis is a species of gecko found in the Pilbara region of Western Australia. They resemble other species of the genus Crenadactylus, tiny clawless Australian geckos found across a large area of the continent, but has persisted as an ancient lineage in a region of the northwest.