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A new species of Acanthodactylus, A. tilburyi, is described from north and central Saudi Arabia. It occurs on aeolian sand slopes and is most closely related to A. gongrorhynchatus and A. haasi.

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Differences in surface structure (ober- hautchen) of body scales of lacertid lizards involve cell size, shape and surface profile, presence or absence of fine pitting, form of cell margins, and the occurrence of longitudinal ridges and pustular projections. Phylogenetic information indicates that the primitive pattern involved narrow strap-shaped cells, with low posteriorly overlapping edges and relatively smooth surfaces. Deviations from this condition produce a more sculptured surface and have developed many times, although subsequent overt reversals are uncommon. Like variations in scale shape, different patterns of dorsal body microornamentation appear to confer different and conflicting performance advantages. The primitive pattern may reduce friction during locomotion and also enhances dirt shedding, especially in ground-dwelling forms from moist habitats. However, this smooth microornamentation generates shine that may compromise cryptic coloration, especially when scales are large. Many derived features show correlation with such large scales and appear to suppress shine. They occur most frequently in forms from dry habitats or forms that climb in vegetation away from the ground, situations where dirt adhesion is less of a problem. Microornamentation differences involving other parts of the body and other squamate groups tend to corroborate this functional interpretation. Microornamentation features can develop on lineages in different orders and appear to act additively in reducing shine. In some cases different combinations may be optimal solutions in particular environments, but lineage effects, such as limited reversibility and different developmental proclivities, may also be important in their genesis. The fine pits often found on cell surfaces are unconnected with shine reduction, as they are smaller than the wavelengths of most visible light.

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The lizard fauna of Jordan is very diverse and forms 55.5% of the terrestrial herpetofauna of the country. Lizard species of Arabian origin form the highest percentage (43%) of the lizards, followed by Saharo-Sindian (35%), Palaearctic (20%) and only 2% with Afrotropical affinities. 69.1% of the lizard species inhabit two ecozones: Badia (Eastern Desert); and Wadi Araba and Wadi Rum. The Badia may form the focal point for the evolution of certain Acanthodactylus species. Jordan forms the southernmost limit of the distribution of some Palaearctic species (i.e. Lacerta media, L. laevis, Pseudopus apodus) and they inhabit the Mediterranean ecozone. The presence of diverse habitats in Jordan allowed certain allopatric congeneric species of the genus Ptyodactylus to live in isolation from one another. Southern Jordan and Wadi Rum are part of the Levantine land bridge and act as a “biogeographical filter”. Most of the species found in Wadi Rum are of Arabian affinities and their distribution does not extend towards the west.

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Aim Body size is instrumental in influencing animal physiology, morphology, ecology and evolution, as well as extinction risk. I examine several hypotheses regarding the influence of body size on lizard evolution and extinction risk, assessing whether body size influences, or is influenced by, species richness, herbivory, island dwelling and extinction risk. Location World-wide. Methods I used literature data and measurements of museum and live specimens to estimate lizard body size distributions. Results I obtained body size data for 99% of the world`s lizard species. The body size–frequency distribution is highly modal and right skewed and similar distributions characterize most lizard families and lizard assemblages across biogeographical realms. There is a strong negative correlation between mean body size within families and species richness. Herbivorous lizards are larger than omnivorous and carnivorous ones, and aquatic lizards are larger than non-aquatic species. Diurnal activity is associated with small body size. Insular lizards tend towards both extremes of the size spectrum. Extinction risk increases with body size of species for which risk has been assessed. Main conclusions Small size seems to promote fast diversification of disparate body plans. The absence of mammalian predators allows insular lizards to attain larger body sizes by means of release from predation and allows them to evolve into the top predator niche. Island living also promotes a high frequency of herbivory, which is also associated with large size. Aquatic and nocturnal lizards probably evolve large size because of thermal constraints. The association between large size and high extinction risk, however, probably reflects a bias in the species in which risk has been studied.

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Jordan has a very diversified morphology, which is reflected also in the diversity of its herpetofauna. A total 90 amphibian and reptilian species is known to inhabit Jordan. Of those three are amphibians, with the fourth species most probably already extinct, 47 are lizard species, 35 are snake species and five turtle species. The amphibians are represented by three different families, lizards and snakes both by seven families and turtles by four families. The distribution, ecology and systematics for most species are given.

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Aim: Deserts are generally perceived as areas of low diversity, and hence receive little attention from researchers and conservationists. Squamates are the dominant group of vertebrates in arid regions, and as such represent an ideal model to study biodiversity patterns in these areas. We examine spatial patterns of diversity, evolutionary history and endemism of terrestrial squamates of the Arabian Peninsula and test hypotheses on the role of topography and history of isolation so as to identify possible environmental drivers of diversification. Location: The Arabian Peninsula. Taxon: Squamate reptiles (Squamata; lizards and snakes). Methods: We generated distribution maps for all Arabian squamate species (including yet undescribed) and reconstructed their phylogenetic relationships using existing and newly produced genetic data for nearly all the species. We assessed patterns of the distribution of species richness, phylogenetic diversity and phylogenetic en demism across the peninsula to identify areas that could be considered evolutionary or endemicity hotspots for squamates. We evaluated community turnover across the peninsula and assessed the possible environmental drivers affecting the diversity of Arabian squamates in a regression framework. Results: The main hotspots of Arabian squamate diversity are mostly along the mountains that rim the peninsula while the most arid, central regions support a low diversity of species. The distribution of the phylogenetic diversity mirrors that of the species richness. Phylogenetic endemism is also highest in the mountains, especially when only endemic species are analysed. The deserts of northern Arabia are poor in terms of species richness and they show low connectivity to the peninsular communities. Topographic heterogeneity is the strongest predictor for Arabian squamates, followed by elevation. There is no correlation between richness and temperature. Main conclusions: The mountains of Arabia support rich and unique squamate communities that are dominated by local radiations of closely related and narrow-ranging species. In particular, the Asir Mountains of SW Arabia, Dhofar Province of Oman and the Hajar Mountains of northern Oman and UAE show unprecedented levels of squamate endemism and phylogenetic endemism. While many generalist species range across Arabia, a low number of species is shared between the peninsula and mainland Asia, indicating an effective isolation of the Arabian fauna. Squamate richness is highest in heterogeneous, topographically complex habitats.

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Acanthodactylus lizards are among the most diverse and widespread diurnal reptiles in the arid regions spanning from North Africa across to western India. Acanthodactylus constitutes the most species-rich genus in the family Lacertidae, with over 40 recognized species inhabiting a wide variety of dry habitats. The genus has seldom undergone taxonomic revisions, and although there are a number of described species and species-groups, their boundaries as well as their interspecific relationships are largely unresolved. We constructed a multilocus phylogeny, combining data from two mitochondrial (12S, cytb) and three nuclear (MC1R, ACM4, c-mos) markers for 302 individuals belonging to 36 known species, providing the first large-scale time-calibrated molecular phylogeny of the genus. We evaluated phylogenetic relationships between and within species-groups, and assessed Acanthodactylus biogeography across its known range. Acanthodactylus cladogenesis is estimated to have originated in Africa due to vicariance and dispersal events from the Oligocene onwards. Radiation started with the separation into three clades: the Western and scutellatus clades largely distributed in North Africa, and the Eastern clade occurring mostly from Arabia to south-west Asia. Most Acanthodactylus species diverged during the Miocene, possibly as a result of regional geological instability and climatic changes. We support most of the current taxonomic classifications and phylogenetic relationships, and provide genetic validity for most species. We reveal a new distinct blanfordii species-group, suggest new phylogenetic positions (A. hardyi, A. masirae), and synonymize several species and subspecies (A. lineomaculatus, A. boskianus khattensis and A. b. nigeriensis) with their phylogenetically closely-related species. We recommend a thorough systematic revision of taxa exhibiting high levels of intraspecific variability as well as clear evidence of phylogenetic complexity such as A. guineensis, A. grandis, A. dumerilii, and A. senegalensis and the pardalis and erythrurus species-groups.