Academic literature on the topic 'Diplodactylidae'

We employed a molecular phylogenetic approach using the mitochondrial ND2 gene and five associated tRNAs(tryptophan, alanine, asparagine, cysteine, tyrosine) and the nuclear RAG1 gene to investigate relationships within thediplodactylid geckos of New Caledonia and particularly among the giant geckos, Rhacodactylus, a charismatic group oflizards that are extremely popular among herpetoculturalists. The current generic allocation of species within NewCaledonian diplodactylids does not adequately reflect their phylogenetic relationships. Bavayia madjo, a high-elevationendemic is not closely related to other Bavayia or to members of any other genus and is placed in a new genus, Paniegekkogen. nov. Rhacodactylus is not monophyletic. The small-bodied and highly autapomorphic genus Eurydactylodes isembedded within Rhacodactylus as sister to R. chahoua. Rhacodactylus ciliatus and R. sarasinorum are sister taxa but arenot part of the same clade as other giant geckos and the generic name Correlophus Guichenot is resurrected for them.Remaining New Caledonian giant geckos (R. leachianus, R. trachrhynchus, R. auriculatus) receive weak support as amonophyletic group. Although the monophyly of Rhacodactylus (including Eurydactylodes) exclusive of Correlophuscannot be rejected, our results support the recognition of a R. chahoua + Eurydactylodes clade separate fromRhacodactylus sensu stricto. Because of the distinctiveness of Eurydactylodes from R. chahoua (and other NewCaledonian ‘giant geckos’), we retain this name for the four species to which it has been consistently applied and erect anew genus, Mniarogekko gen. nov. to accommodate R. chahoua. There is little genetic differentiation within the narrowlydistributed Corrrelophis sarasinorum, but C. ciliatus from southern New Caledonia are both genetically andmorphologically differentiated from a recently discovered Correlophus from the Îles Belep, north of the Grande Terre,which is here described as C. belepensis sp. nov. Although only subtley different morphologically, the populations ofMniarogekko from the far northwest of the Grande Terre and from the Îles Belep are strongly differentiated geneticallyfrom M. chahoua populations in the central part of the Grande Terre and are described as M. jalu sp. nov. Rhacodactylusauriculatus exhibits some genetic substructure across its nearly island-wide range in New Caledonia, but overalldivergence is minimal. Rhacodactylus leachianus exhibits low levels of divergence across its range and southern insularforms previously assigned to R. l. henkeli are not divergent from southern Grande Terre populations. The few populationsof R. trachyrhynchus sampled are strongly divergent from one another and a specimen from Îlot Môrô near the Île des Pinsis especially distinctive. This specimen and others examined from Îlot Môrô are morphologically assignable to the speciesdescribed by Boulenger in 1878 as Chameleonurus trachycephalus and is recognized here as a full species. New diagnosesare provided for each of the eight genera of endemic New Caledonian diplodactylid geckos now recognized. The resultsof our study necessitate determinations of the conservation status of the new species described or recognized.Mniarogekko jalu sp. nov. is considered Endangered, but is locally abundant. Correlophus belepensis sp. nov. isconsidered Critically Endangered and is restricted to the ultramafic plateaux of Île Art. Although described from the Îledes Pins, we have only been able to confirm the existence of Rhacodactylus trachycephalus on the tiny satellite island ÎlotMôrô and consider it to be Critically Endangered. If indeed restricted to this islet, R. trachycephalus may well have the smallest range and perhaps the smallest population of any gecko in the world.

The stone geckos of the Diplodactylus vittatus species-group are robust terrestrial geckos, mainly distributed through the southern half of Australia. Recent molecular analyses indicate that the current taxonomy significantly under-represents the true diversity in this group. Here we assess the morphological variation in the currently recognized species D. vittatus and D. granariensis, including the subspecies D. g. rex. We redescribe D. vittatus and D. granariensis, resurrect D. furcosus from the synonymy of D. vittatus and describe D. calcicolus sp. nov. and D. wiru sp. nov. from semiarid habitats in western and southern Australia. Other than D. g. rex, most taxa are very similar for such characters as scalation, body and tail shape and size, but colour patterns show species-specific modal conditions, and the largely allopatric distributions mean that most areas support only one or two species which can be distinguished through a combination of characters. Further genetic data is required to resolve the systematic status and geographic distribution of additional deeply divergent genetic lineages in eastern Australia.

A new species of diplodactylid gecko in the genus Strophurus Fitzinger, from central Queensland, Australia, is described herein as Strophurus trux sp. nov. It is similar to the recently described Strophurus congoo Vanderduys from north Queensland and apparently shares a habitat preference for Triodia hummock open woodlands. It is notably different from the latter in possessing a vivid yellow to golden eye. It is only known from one small area of the Brigalow Belt Bioregion, although it is expected to occur more widely than the one area in which it has been found. It is likely that it is endemic to the Brigalow Belt Bioregion.

We describe a new species of velvet gecko (Diplodactylidae: Oedura) from north-east Queensland, Australia. Oedura jowalbinna sp. nov. is a robust, medium-sized (SVL 60–69 mm) gecko that is readily distinguished from its congeners by its distinctive dorsal colour pattern. The dorsum is grey with faint freckling and a pale, dark-edged band across the neck and another across the base of the tail. The combination of a yellow tail and a grey body is also distinctive. Oedura jowalbinna sp. nov. also differs significantly from the most similar congener, O. coggeri, in a multivariate analysis of morphology and scalation, primarily due to its smaller body size, higher interorbital, supralabial and infralabial scale counts, and lower subdigital lamellae scale count. These traits are generally non-overlapping between O. jowalbinna sp. nov. and O. coggeri, however, more individuals of O. jowalbinna sp. nov. need to be assessed to accurately determine variation within the new species. All O. jowalbinna sp. nov. were found at night on overhangs in dissected sandstone escarpment south-west of the town of Laura. Surveys are required to determine the distribution of O. jowalbinna sp. nov. across the sandstone escarpments of the Laura region. This species is the third reptile species (along with the skinks Ctenotus quinkan and C. nullum) described that has a highly localised range centred on the sandstone escarpments of the Laura region. Additionally, included herein is a comparison of O. coggeri and O. monilis. Typical dorsal colour pattern differs between these two species but the large amount of variation (particularly in O. coggeri) merges these differences. Oedura coggeri and O. monilis could not be distinguished in multivariate analyses of morphology and scalation. Genetic data and further analyses of colour pattern, morphology and scalation are required to resolve species boundaries within and between these two species.

Detailed examination and description of structures in nature, relative to the environments in which they occur, provides evidence for the function of these structures. Here I describe the oberhautchen (outer skin surface) of 24 species of Australian carphodactyline (Squamata: Carphodactylidae) and diplodactyline gecko (Squamata: Diplodactylidae). Using methods specially adapted for the purpose, I describe details of skin microornamentations, examined at high magnification, of these geckos, and examine relationships between these skin characteristics and environmental conditions, substrate use, hydrophobic properties, and evaporative water loss (EWL), with a view to determining the function of these features. I used 24 species (and populations therein) of geckos collected from northern and western Queensland, and from the Great Victoria Desert, South Australia, as subjects for my descriptions. To examine the oberhautchen of living lizards, I adapted and tested a method for creating extremely detailed moulds of surfaces using polyvinylsiloxane impression material and epoxy resin (Epirez 123®, ITW Polymers & Fluids). This method produces exceptional quality reproductions of complex microornamentations within the oberhautchen of living lizards. Using scanning electron microscopy on the moulds I created, I examined scale characteristics (primary scale size, secondary scale size, spinule length and density, pit diameter and density, furrow width and depth, percentage of knobs covering scales, and hair sensor characteristics including hair sensors per scale, hair sensors per square millimeter, bristles per sensor, bristles per square millimeter, and hair sensor diameter), I related these to body size, substrate use, environmental conditions at the centre of each species’ geographic range, and phylogeny, using univariate statistics and canonical discriminant function analysis. Carphodactyline geckos are quite different from diplodactyline geckos, and have larger body size, larger primary scales, shorter spinules, greater numbers of hair sensors and bristles per square millimeter, knobs and larger hair sensor diameters. Examining both carphodactyline and diplodactylines together, I found that terrestrial geckos tend to be smaller, live in xeric conditions, and usually have smaller scales and higher numbers of bristles and hair sensors per square millimeter. Nonterrestrial geckos tend to be larger, and live in more mesic and hydric conditions, and usually have larger scales and fewer hair sensors and bristles per square millimeter. Because geckos in xeric habitats live in dry conditions, they may need more sensory information about their environment, to enable them to select appropriate shelter. I traced the character evolution of hair sensor bristle shape, and found that bottlebrush-shaped hair sensors with many hairs appear to be primitive, whereas tapered hair sensors of various shapes with fewer hairs appear to be derived. The causes of evolutionary differences in bristle shape and hair sensor number was not clear from the variables I examined. Hydrophobicity is thought to enhance the adhesiveness of geckos with adhesive toe pads, by keeping these surfaces clean. Because specialized adhesive foot scales are evolutionarily derived from the body scales, I examined the hydrophobic properties of body scales. To estimate hydrophobicity, I used a sessile drop technique to quantify contact angles of droplets of distilled water. Tiny (0.25 μL) droplets of distilled water were incrementally increased in size and photographed at high resolution, and contact angles of droplets were used to predict the hydrophobic properties of the dorsal skin surface of geckos. I established which species were most hydrophobic and which dorsal scale characteristics had the strongest relationships with hydrophobic properties. Several species had superhydrophobic skin (advancing contact angles greater than 150°), including Lucasium damaeum, Strophurus taeniatus, Diplodactylus conspicillatus (Winton population), Oedura rhombifer, and Lucasium steindachneri. Geckos with high hydrophobicity were characterized by skin characteristics that promoted rough surface adaptation, especially small primary scales and long spinules. The great range of variation in gecko oberhautchen is likely to have some functional significance. However, most functions suggested in the literature (ecdysis, coping with varying temperatures on different parts of the body, pheromone capture, retention, and dispersal, the creation or reduction of friction, the reflection or channeling of solar radiation, wear prevention) can be rejected as explanations for variation in the oberhautchen of Australian gecko skin. I provide evidence that high hydrophobic properties of the skin help geckos remain clean. Hydrophobicity was, on average, higher in terrestrial species and in species living closer to the ground (and hence, likely to come into contact with dust and dirt), than in non-terrestrial species living away from the ground. Terrestrial geckos, as a group, had longer spinules and smaller scales than saxicolous and arboreal geckos, enhancing their hydrophobic properties. With the effects of phylogeny removed hydrophobicity was related to distance from the ground, indicating that these two characters evolve together. Recent studies have linked evaporative water loss rates with scale characteristics of reptiles. I measured the EWL of Australian geckos gravimetrically, using the flow-through chamber technique, to examine patterns in water loss rates of Australian geckos in relation to scale characteristics, body size and habitat. Evaporative water loss was strongly correlated with body size, larger geckos had larger body surface area and lost more water than smaller geckos. Mass-specific water loss rates were correlated with habitat use; terrestrial species lost more water than arboreal and saxicolous species, which did not differ in their water loss. In addition, species with larger scales tended to have lower water loss rates, and the evolution of deeper scale furrows was correlated with the evolution of higher EWL. In summary, my work provides evidence that, not only are variations in Australian gecko skin morphology influenced by phylogenetic relationships, but at least some characters appear to have functional significance. Xeric-dwelling, terrestrial geckos have more sensory organs than do non-terrestrial mesic and hydric-dwelling geckos, likely because they require accurate information on environmental conditions. Terrestrial geckos tended to have smaller scales and longer spinules than non-terrestrial geckos, possibly to enhance their hydrophobicity. Terrestrial geckos also had higher EWL rates than saxicolous and arboreal geckos, but may be able to avoid high water loss by using burrows as shelter. Finally, terrestrial and xeric dwelling species tended to be smaller than non-terrestrial mesic and hydric dwelling species.