Temperature-Dependent Sex Determination in Gekko japonicus (Gekkonidae, Reptilia)

The effects of temperature on sexual differentiation in early development of the gekkonid lizard, Gekko japonicus were studied. The eggs were collected within 24 hr after the oviposition and were incubated at 20, 24, 28 and 32°C. The number of eggs hatched was 14 at 24°C, 20 at 28°C and 21 at 32°C. Hatching never occurred at 20°C. The hatched lizards without Müllerian ducts were judged as males. The sex of all lizards with Müllerian ducts were identified histologically. The sex ratios, male/(male+female), were 0.07 at 24°C, 0.75 at 28°C and 0.24 at 32°C. The disparities of the sex ratio from 1/2 were statistically significant and differences in the sex ratio with various incubation temperatures were also significant. These sex ratios can probably be best interpreted by a temperature-dependent sex determination. The different sex ratios do not seem to be related to a predetermination of sex with a differential mortality.     

A New Species of the Gekko japonicus Group(Squamata: Gekkonidae) from Southwest China

A new species of the Gekko(Squa ma ta:Gekkonidae)is described from the border of Sichuan and Yunnan Province,southwest China,based on distinct morphological and molecular features.Gekko jinjiangensis sp.nov.is distinguished from congeners by a combination of the following characters:size small(SVL 50.2–61.6 mm,n=13);nares in contact with rostral;interorbital scales between anterior corners of the eyes 20–24;ventral scales between mental and cloacal slit 146–169;midbody scale rows 111–149;ventral scale rows 31–47;subdigital lamellae on first toe 8–11,on fourth toe 11–15;no webbing in the fingers and toes;with tubercles on uapper surface of fore and hind limbs;precloacal pores 4–5 in males;postcloacal unilateral tubercles 1–2;dorsal surface of body with 8–9 large greyish brown markings between nape and sacrum.In molecular analyses,the new species is sister to G.scabridus,but separated from them by approximately 9.9%–12.2%in genetic divergence as shown by a fragment of the partial mitochondrial ND2 gene.The new species is the highest Gekko with elevation range from 2000 to 2476 m.Further surveys are recommended to better understand the occurrence and population status of the new species.     

Gas exchange morphometry of the lungs of the tokay,Gekko gecko L. (Reptilia: Squamata: Gekkonidae)

The tokay lizard (Gekko gecko) possesses singlechambered lungs, eacch of which is a mirror image of the other reflected in the midsagittal body plane. When standard techniques are employed for instilling 2% phosphate-buffered glutaraldehyde to three-quarters of the total lung capacity, neither the left nor the right lung is consistently larger. Internally, the lungs are characterized by a row of 11 dorsomedial niches and by honeycomb-like (faveolar) gas exchange tissue, which is deeper cranially than caudally. Based upon mean values for all experimental animals, a 100-g tokay would have an overall anatomical diffusion factor (respiratory surface area divided by the appropriate _ht) of 203 cm²·m^-1·100 g^-1, 61% of which is located on the interfaveolar septa. Of the total septal anatomical diffusion factor, 94% is evenly divided between the anterior and middle thirds of the lung, with 6% in the posterior third. The 39% of the anatomical diffusion factor located on the inner lung wall is predominantly (76%) in the middle and posterior lung thirds, with only 24% in the anterior region. These tendencies toward heterogeneous distribution of anatomical diffusion factor were most pronounced in a 55 g juvenile animal. In this animal the total anatomical diffusion faxtor/body mass was 3.6 times that of a 197 g adult. This difference was attributable to a greater body massspecific lung volume and respiratory surface area as well as to a greater surface-to-volume ratio in the parenchyma and to a thinner air-blood diffusion barrier in the juvenile animal.Abbreviations ADF anatomical diffusion factor - %AR percentage of potential respiratory surface area which makes up S_AR - DtO₂ diffusing capacity for air-blood tissue barrier - IUR isotropic uniform randomly distributed - bm body mass - %P percentage of lung volume devoted to parenchyma - S _A potential respiratory surface area (S _L minus the surface area of the trabeculae) - S _ANR non-respiratory surface area - S _AR respiratory surface area - S _L total internal surface area of the lung - S _v surface area-to-volume ratio in parenchyma - _ht harmonic mean thickness of the air-blood tissue barrier - V _L morphometrically determined volume of both lungs, fixed at 0.75· V _Lm - V _Lm maximal lung volume, similar to total lung capacity in mammals - V _Lr resting lung volume, similar to functional residual capacity in mammals - VP morphometrically determined volume of parenchyma of both lungs, fixed at three-quarters of V_Lm     

Genetic Structure of the Red-spotted Tokay Gecko,Gekko gecko(Linnaeus, 1758)(Squamata: Gekkonidae) from Mainland Southeast Asia

This study was performed to explore the genetic diversity and genetic structure of red-spotted tokay geckos(Gekko gecko) from 23 different geographical areas in Thailand, Lao PDR and Cambodia. The mitochondrial tRNAGln/tRNA-Met/partial NADH dehydrogenase subunit 2 from 166 specimens was amplified and sequenced. A total of 54 different haplotypes were found. Highly significant genetic differences occurred between populations from different localities. The haplotype network revealed six major haplogroups(G1 to G6) belonging to different clades(clade A–E). Clade D and clade E were newly observed in this study. Haplogroup G4(clade D) was a sympatric population with haplogroup G1(clade B). The populations from northern Thailand were divided into two distinct haplogroups separated by mountain range. Genetic structure and genetic differentiation of the tokay in Southeast Asia was related to the geographical region sampled, spatial distance and natural barriers. Our results indicate that red-spotted tokay geckos from mainland Southeast Asia are cryptically diverse. Morphological comparisons, in addition to an intensive genetic investigation covering the whole species range, are needed to clarify the systematic and population structure of this species group.     

Extensive Natural Hybridization Between Two Geckos,Gekko tawaensis and Gekko japonicus (Reptilia: Squamata), Throughout Their Broad Sympatric Area

The status of natural hybridization between the two Japanese geckos, Gekko tawaensis and Gekko japonicus, was surveyed by use of 15 diagnostic allozyme loci. Of 438 specimens examined, 9 were identified as F_l, 1 was a first backcross with G. japonicus, and 15 were identified as more successive generations. Hybridizations were detected at 7 of the 15 localities interspersed throughout a broad sympatric area of the two species, forming a mosaic hybrid zone. A comparison of species–hybrid composition between 2-year samples from a single locality and a 5-year interval showed no evidence for progressive introgression or establishment of a hybrid swarm, despite constant emergences of F_l hybrids. Nonprevalence of the hybrid genotypes was also indicated by the analysis using hybrid index scores for all other localities examined. These results suggest that strong selection acts against hybrid genotypes. Morphological features of hybrid individuals were also provided.     

Mitochondrial Diversity and Phylogeographic Patterns of Gekko gecko(Squamata: Gekkonidae) in Thailand

The Tokay Gecko, Gekko gecko(Linnaeus, 1758) is widely distributed in Asia and there have been concerns regarding locally decreasing populations due to overexploitation for traditional Chinese medicine. Previous studies of the genetic relationships of G. gecko populations included few populations from Thailand. Here we investigated the phylogeographic patterns of G. gecko from different regions in Thailand using mitochondrial cytochrome b sequences. Phylogenetic analyses revealed two lineages: one(Lineage A) comprising populations from Laos, Vietnam, and Thailand; and a second(Lineage B) comprising three genetically distinct groups within Thailand alone. Some Thai populations were found to have both lineages represented within them. Highly significant genetic differentiation(FST) showed geographic population structuring in Lineage B, indicating limited gene flow among groups in Thailand. Although G. gecko has a wide distribution and is well adapted to human habitation, the observed genetic structure could potentially be explained by geographic barriers such as mountain ranges. In Lineage A, our study provided primary phylogeographic evidence for lineage mixture that might be a result of human-mediated transport. Future research should include more extensive sampling across the geographic distribution of G. gecko and a landscape genetics approach could be applied for conservation planning.     

Burrow Characteristics and Microhabitat Use of the Turpan Wonder Gecko Teratoscincus roborowskii(Squamata,Gekkonidae)

Burrow structural charactersitcs and microhabitat use of the Turpan wonder gecko Teratoscincus roborowskii(Gekkonidae) were studied between April and September of 2013 in the Turpan Eremophytes Botanic Garden,in the Turpan Depression of Western China.Burrow depth,entrance orientation,entrance height and width were observed.We assessed microhabitat selection and noted differences in microhabitat use among males,females,and juveniles.The magnitude of selection was measured using Jacobs' index of selectivity.Entrance height and width of the burrows of adults were significantly larger than those of juveniles,but the difference in burrow depth was not significant.The directional orientation of the burrow entrance showed a preference for the north-northeast and south-southeast,which were likely influenced by local prevailing winds and sunlight.Both the adult and juvenile geckos prefer to construct their burrows in sandy soil within a layer of loose soil whose thickness is greater than 30 cm.A majority of the burrows were located within 20 m of the nearest plant.Nearly half(48%) of the entrances of juveniles were located within 5 m of the nearest vegetation,significantly different from those of the adults.Results showed that the Turpan wonder gecko did not utilize microhabitats according to their availability,but rather that it preferred microhabitats which contained dead wood or the caper bush.Our results suggested that burrow characteristics and microhabitat selection were important factors in T.roborowskii adaptation to harsh and arid desert habitats.     

Systematics, biogeography, and evolution of Hemidactylus geckos (Reptilia: Gekkonidae) elucidated using mitochondrial DNA sequences

With more than 80 species inhabiting all warm continental land masses and hundreds of intervening continental and oceanic islands, Hemidactylus geckos are one of the most species-rich and widely distributed of all reptile genera. They consequently represent an excellent model for biogeographic, ecological, and evolutionary studies. A molecular phylogeny for Hemidactylus is presented here, based on 702 bp of mtDNA (303 bp cytochrome b and 399 bp 12S rRNA) from 166 individuals of 30 species of Hemidactylus plus Briba brasiliana, Cosymbotus platyurus, and several outgroups. The phylogeny indicates that Hemidactylus may have initially undergone rapid radiation, and long-distance dispersal is more extensive than in any other reptilian genus. In the last 15 My, African lineages have naturally crossed the Atlantic Ocean at least twice. They also colonized the Gulf of Guinea, Cape Verde and Socotra islands, again sometimes on more than one occasion. Many extensive range extensions have occurred much more recently, sometimes with devastating consequences for other geckos. These colonizations are likely to be largely anthropogenic, involving the 'weedy' commensal species, H. brookii s. lat, H. mabouia, H. turcicus, H. garnotii, and H. frenatus. These species collectively have colonized the Mediterranean region, tropical Africa, much of the Americas and hundreds of islands in the Pacific, Indian, and Atlantic oceans. Five well-supported clades are discernable in Hemidactylus, with the African H. fasciatus unallocated. 1. Tropical Asian clade: (Cosymbotus platyurus (H. bowringii, H. karenorum, H. garnotii)) (H. flaviviridis (Asian H. brookii, H. frenatus)). 2. African H. angulatus and Caribbean H. haitianus. 3. Arid clade, of NE Africa, SW Asia, etc.: (H. modestus (H. citernii, H. foudai)) (H. pumilio (H. granti, H. dracaenacolus) (H. persicus, H. macropholis, H. robustus, H. turcicus (H. oxyrhinus (H. homoeolepis, H. forbesii))). 4. H. mabouia clade (H. yerburii, H. mabouia). 5. African-Atlantic clade: H. platycephalus ((H. agrius, H. palaichthus) (H. longicephalus, H. greeffi, H. bouvieri, Briba brasiliana))). Cosymbotus and Briba are synonymized with Hemidactylus, and African populations of H. brookii separated as H. angulatus, with which H. haitianus may be conspecific. Some comparatively well-sampled widespread species show high genetic variability (10-15% divergence) and need revision, including Cosymbotus platyurus, H. bowringii, Asian H. brookii, H. frenatus, H. angulatus, and H. macropholis. In contrast, most populations of H. mabouia and H. turcicus are very uniform (1-2% divergence). Plasticity of some of the morphological features of Hemidactylus is confirmed, although retention of primitive morphologies also occurs.     

A new species of Thecadactylus from Sint Maarten, Lesser Antilles (Reptilia, Squamata, Gekkonidae)

We describe a new species of Thecadactylusfrom the Caribbean island of Sint Maarten. The new species differs from all other species in the genus by having a distinct dorsal pattern of numerous irregular but sharply deliminated black spots and blotches on an otherwise almost patternless background.     

Morphology of the stomach of the tropical house gecko Hemidactylus mabouia (Squamata: Gekkonidae)

Rodrigues Sartori, S. S., Nogueira, K. O. P. C., Rocha, A. S. and Neves, C. A. 2011. Morphology of the stomach of the tropical house gecko Hemidactylus mabouia (Squamata: Gekkonidae). —Acta Zoologica (Stockholm) 92 : 179–186. Hemidactylus mabouia is a common species in Brazil, which facilitates its use in research in several areas and allows display it as a benchmark for studies with reptiles. To study the morphology of the stomach of H. mabouia, we carried out anatomical, histological and histochemical analysis. The stomach of H. mabouia is ‘J’ shaped and can be divided into oral fundic (OF), aboral fundic (AF) and pyloric regions. The surface epithelium is composed of mucosecretory cells (MC) containing neutral mucins. In the lamina propria of the OF region, are large ramified tubulo‐acinar glands, which become smaller, less ramified and more tubular towards the AF region, and are simple tubular and short in the pyloric region. The fundic glands contain differentiated neck and pit. The neck is composed of MC containing neutral mucins and the pit is made of oxyntopeptic cells (OC). The OC of the OF region contained many zymogen granules, while those of the AF region contained few zymogen granules and many mitochondria, which suggests the existence of a gradient of pepsinogen and hydrochloric acid secretion. Pyloric glands consisted of MC containing neutral mucins and both argyrophil and argentaffin endocrine cells.     

Systematics,biogeography and evolution of the endemic Hemidactylus geckos (Reptilia,Squamata, Gekkonidae) of the Cape Verde Islands: based on morphology and mitochondrial and nuclear DNA sequences

A total of 1854 bp of mitochondrial DNA (669 bp of cytochrome b (cyt b) and 386 bp of 12S rRNA), and 804 bp of a nuclear gene (RAG2) were investigated in endemic Hemidactylus from eight Cape Verde Islands, and used to explore their phylogeny, biogeography and evolution. Maximum‐likelihood, maximum‐parsimony and Bayesian analyses based on mtDNA revealed four well‐supported clades with uncorrected genetic divergences of 7.8–12.4% in the cyt b plus 12S rRNA genes, which were also supported by nuclear DNA. A population from the southern island of Fogo is the most divergent in both molecules and morphology and is described as Hemidactylus lopezjuradoi sp. n., and the populations on Sal and Boavista are also assigned species status as H. boavistensis. Although divergent in their DNA, the clade on S. Nicolau and that in the north‐western islands are morphologically similar and both are assigned to H. bouvieri for the present. Hemidactylus b. razoensis from Raso is genetically similar to H. b. bouvieri and differs only in its smaller body size. A molecular clock suggests that the ancestor of the endemic Hemidactylus of the Cape Verde Islands colonized the archipelago approximately 10 ± 2.48 Mya, perhaps reaching the north‐eastern islands first. The H. lopezjuradoi lineage separated soon after, and the north‐western islands were colonized progressively but slowly, S. Nicolau probably being reached first, then S. Vicente and islands on the same bank, and finally Sto. Antão, which is likely to have been colonized less than 1 Mya. Hemidactylus boavistensis is abundant on the arid islands where it occurs, but H. bouvieri appears to have been uncommon at least since it was described 130 years ago, and the same may be true of H. lopezjuradoi sp. n. The impact of introduced H. angulatus and H. mabouia on the endemic Hemidactylus of the Cape Verde Islands is not clear, but the discovery of substantial genetic diversity in endemic Cape Verde Hemidactylus means that the conservation requirements of the group should be reassessed.     

Hemidactylus frenatus (Squamata: Gekkonidae): call frequency, movement and condition of tail in Costa Rica

Call frequency and movements of the gecko Hemidactylus frenatus were studied in Punta Morales, Costa Rica from April 1999 through May 2000. Call activity of H. frenatus was positively related to air temperature at night and throughout the year. Higher activity was at dusk, dawn, and during the hottest months. Call frequency was related with gecko abundance per month, although not during the night. More males and females had a regenerated tail compared to juveniles, the last ones could have it complete or regenerated. Females moved longer distances than males and juveniles. Adults were found higher on walls. Males and females were recaptured more times than juveniles, and the period of time between their recaptures was longer. Members of this population do not seem to be as aggressive to other geckos as mentioned in the literature.     

Fine structure of the dorsal lingual epithelium of the lizard, Gekko japonicus (Lacertilia, Gekkonidae)

Three different types of lingual papilla were observed by scanning electron microscopy on the dorsal lingual epithelium of the lizard Gekko japonicus. Dome-shaped lingual papillae were located at the apex. Flat, fan-shaped lingual papillae were seen in the widest area of the lingual body. Long, scale-like lingual papillae were arranged on the latero-posterior dorsal surface. At higher magnification, microvilli and microridges were seen to be widely distributed over the surface of the papillae. By light microscopy, the epithelium of the dome-shaped papillae was composed of single, columnar epithelial cells filled with secretory granules. The tip of the epithelium of the fan-shaped and scale-like papillae was composed of stratified squamous epithelial cells without granules. The major part of the epithelium of these two types of papilla, except the tip area, was also composed of single, columnar epithelial cells with secretory granules. By transmission electron microscopy, a nucleus without a defined shape was seen to be located in the basal part of each of the single, columnar epithelial cells. Rough-surfaced endoplasmic reticulum and Golgi apparatus were well developed around the nucleus. The other, major part of the cytoplasm was filled with the spherical secretory granules, a large number of which had very electron-dense cores and moderately electron-dense peripheral regions. In the stratified squamous epithelium, a nucleus, which tended to be condensed on the free-surface side, was located in the center of each cell. Mitochondria, endoplasmic reticulum, and vesicles were observed in the cytoplasm.     

Eimeria turcicus N. Sp. (Apicomplexa: Eimeriidae) from the Mediterranean Gecko, Hemidactylus turcicus (Sauria: Gekkonidae)

ABSTRACT. Eimeria turcicus n. sp. (Apicomplexa: Eimeriidae) is reported from the gall bladder of the Mediterranean gecko, Hemidactylus t. turcicus (Linnaeus, 1758) from the Houston Zoo, Texas, USA. Oocysts of this coccidian are elongate and cylindrical, 38.2 × 17.9 (35.2-40.8 × 16.8-20.0)μm, with a smooth, bilayered wall ∼ 1.6 μm thick; shape index 2.1 (1.9-2.3). A polar granule is present, but a micropyle and oocyst residuum are absent. Sporocysts are ovoid, 11.0 × 8.8 (10.0-12.0 × 8.0-9.4) μm, with a smooth, thin wall and suture; shape index 1.3 (1.1-1.4). Each sporocyst contains a residuum measuring 6.0 × 5.1 (4.8-8.0 × 4.8-6.4) μm, additional residual granules scattered among the sporozoites, and two sporozoites that are normally arranged head-to-tail within the sporocyst. Each sporozoite contains a single, ovoid, posterior refractile body and a central nucleus.     

Karyotype Reorganization in the Hokou Gecko (Gekko hokouensis,Gekkonidae): The Process of Microchromosome Disappearance in Gekkota

The Hokou gecko (Gekko hokouensis: Gekkonidae, Gekkota, Squamata) has the chromosome number 2n = 38, with no microchromosomes. For molecular cytogenetic characterization of the gekkotan karyotype, we constructed a cytogenetic map for G. hokouensis, which retains the ancestral karyotype of Gekkota, with 86 functional genes, and compared it with cytogenetic maps for four Toxicofera species that have many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) and that for a lacertid species (Lacerta agilis) with only one pair of autosomal microchromosomes. Ten pairs of G. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilis macrochromosomes (LAG). However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera microchromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis. These results suggest that repeated fusions of microchromosomes may have occurred independently in each lineage of Gekkota and Lacertidae, leading to the disappearance of microchromosomes and appearance of small-sized macrochromosomes.     

The development of cephalic armor in the tokay gecko (Squamata: Gekkonidae: Gekko gecko)

Armored skin resulting from the presence of bony dermal structures, osteoderms, is an exceptional phenotype in gekkotans (geckos and flap-footed lizards) only known to occur in three genera: Geckolepis, Gekko, and Tarentola. The Tokay gecko (Gekko gecko LINNAEUS 1758) is among the best-studied geckos due to its large size and wide range of occurrence, and although cranial dermal bone development has previously been investigated, details of osteoderm development along a size gradient remain less well-known. Likewise, a comparative survey of additional species within the broader Gekko clade to determine the uniqueness of this trait has not yet been completed. Here, we studied a large sample of gekkotans (38 spp.), including 18 specimens of G. gecko, using X-rays and high-resolution computed tomography for visualizing and quantifying the dermal armor in situ. Results from this survey confirm the presence of osteoderms in a second species within this genus, Gekko reevesii GRAY 1831, which exhibits discordance in timing and pattern of osteoderm development when compared with its sister taxon, G. gecko. We discuss the developmental sequence of osteoderms in these two species and explore in detail the formation and functionality of these enigmatic dermal ossifications. Finally, we conducted a comparative analysis of endolymphatic sacs in a wide array of gekkotans to explore previous ideas regarding the role of osteoderms as calcium reservoirs. We found that G. gecko and other gecko species with osteoderms have highly enlarged endolymphatic sacs relative to their body size, when compared to species without osteoderms, which implies that these membranous structures might fulfill a major role of calcium storage even in species with osteoderms.     

Ultrastructure of the placentae of the natricine snake,Virginia striatula (Reptilia: Squamata)

Virginia striatula is a viviparous snake with a complex pattern of embryonic nutrition. Nutrients for embryonic development are provided by large, yolked eggs, supplemented by placental transfer. Placentation in this species is surprisingly elaborate for a predominantly lecithotrophic squamate reptile. The embryonic-maternal interface consists of three structurally distinct areas, an omphalallantoic placenta and a regionally diversified chorioallantoic placenta. The chorioallantoic placenta over the embryonic hemisphere (paramesometrial region) of the egg, features close apposition of embryonic and uterine blood vessels because of the attenuate form of the interceding epithelial cells. The periphery of the chorioallantoic placenta, which is adjacent to the omphalallantoic placenta, is characterized by a simple cuboidal uterine epithelium apposed to a stratified cuboidal chorionic epithelium. There are no sites with attenuate epithelial cells and close vascular apposition. The morphology of the omphalallantoic placenta is similar to that of the peripheral chorioallantoic placenta, except that the height of uterine epithelial cells is greater and allantoic blood vessels are not associated with the embryonic epithelium. The functional capabilities of the three placental regions are not known, but structural characteristics suggest that the omphalallantoic placenta and peripheral zone of the chorioallantoic placenta are sites of nutritional provision via histotrophy. The paramesometrial region of the chorioallantoic placenta is also nutritive, in addition to functioning as the primary embryonic respiratory system. The structure of the chorioallantoic placenta of V. striatula is a new placental morphotype for squamate reptiles that is not represented by a classic model for the evolution of reptilian placentation.