Species Of Amphisbaenians Research Articles

Comparative skull osteology of Amphisbaena arda and Amphisbaena vermicularis (Squamata: Amphisbaenidae).

The skull anatomy of amphisbaenians directly influences their capacity to burrow and is crucial for the study of their systematics, which ultimately contributes to our comprehension of their evolution and ecology. In this study, we employed three-dimensional X-ray computed tomography to provide a detailed description and comprehensive comparison of the skull anatomy of two amphisbaenian species with similar external morphology, Amphisbaena arda and Amphisbaena vermicularis. Our findings revealed some differences between the species, especially in the sagittal crest of the parietal bone, the ascendant process, and the transverse occipital crest of the occipital complex. We also found intraspecific variation within A. vermicularis, with some specimens displaying morphology that differed from their conspecifics but not from A. arda. The observed intraspecific variation within A. vermicularis cannot be attributed to soil features because all specimens came from the same locality. Specimen size and soil type may play a role in the observed differences between A. arda and A. vermicularis, as the single A. arda specimen is the largest of our sample and soil type and texture differ between the collection sites of the two species.

Ontogenetic skull variation in a shovel-headed amphisbaenian species.

Leposternon microcephalum is a species belonging to the Amphisbaenia, a group of burrowing reptiles. Amphisbaenia present various morphological and physiological adaptations that allow them to penetrate the ground and live underground, through a system of galleries and permanent chambers that they build themselves. Among the morphological adaptations in this group, those of the skull stand out as it serves as the main excavation tool. Four basic skull shapes are recognized: rounded, keeled, shovel-shaped, and spade-shaped. The skull of L. microcephalum belongs to this last type, which is considered the most specialized. The species inhabits soils that are highly compacted and difficult to penetrate. Among the species of Leposternon present in South America, L. microcephalum has the widest distribution, being found in all Brazilian biomes and neighboring countries such as Bolivia, Argentina, Paraguay, and Uruguay. The analysis of the skull of this species was carried out using three-dimensional geometric morphometrics (3D-GMM), a technique that allows comparative analysis, through robust statistical methods, of shape and its variations, using Cartesian coordinate data from a configuration of homologous landmarks. The technique allows the size and shape components of a structure to be analyzed separately. From an ontogenetic point of view, this methodology had also been used to investigate variations in Cynisca leucura, a member of the Amphisbaenidae with a rounded head. Our hypothesis is that the patterns of morphological differentiation in the skull, mainly in the intermediate and occipital regions, are similar in different Amphisbaenia species. Therefore, the objective of this study was to analyze cranial morphological variations in an ontogenetic series of L. microcephalum using 3D-GMM. Computed Tomographic scans of 13 specimens were analyzed: juveniles (N = 8) and adults (N = 5), based on 20 landmarks that characterize the skull. Principal components and regression analyses between shape (dependent variable) and size (independent variable) showed a clear difference between the cranial morphological pattern of juvenile individuals and that of adults. For instance, young specimens tend to have a dorsoventrally tall neurocranium, with the tip of the snout more anteriorly oriented and its dorsal border subtly curved. Dorsally, the parietal region is thicker and smoothly dome-shaped in juveniles. As in C. leucura, the variation was strongly correlated with the size change from juvenile to adult, indicating a dominant role for ontogenetic allometry in determining skull shape.

New lizard material from two Early Miocene localities in France: Montaigu-le-Blin (MN 2) and Crémat (MN 3)

Squamate faunas from the MN 1–3 intervals (earliest Miocene) are scarcely documented from the European continent. I here describe squamate faunas from two French localities – Montaigu-le-Blin (MN 2) and Crémat (MN 3), the latter being the youngest locality of the Phosphorites du Quercy. The palaeobiodiversity of squamates from these sites is low relative to the faunas described from coeval localities of Amöneburg (MN 2) in Germany and Merkur-North (MN 3) in the Czech Republic. The beginning of the Miocene represents the temporary return to a paratropical humid climate after the relatively cool and dry Oligocene, and the Montaigu and Crémat materials provide previously undocumented components of herpetofaunas and their changes during this crucial time interval in France. The importance of fossil squamates from the area of the Phosphorites du Quercy is therefore highlighted for the beginning of the Miocene as well as the better known Eocene-Oligocene sites. The lizard material of Montaigu includes lacertids and blanids, the latter being represented by Blanus cf. gracilis, one of the oldest records of the genus. Moreover, it shows a higher spatial and temporal distribution of this amphisbaenian species during the Early Miocene than previously known. The material from Crémat consists of few elements which can be allocated to anguids and potentially to lacertids. Detailed figures of the specimens are provided through the means of both photography and micro-CT scanning.

Hidden but Potentially Stressed: A Non-Invasive Technique to Quantify Fecal Glucocorticoid Levels in a Fossorial Amphisbaenian Reptile.

To understand wildlife responses to the changing environment, it is useful to examine their physiological responses and particularly their endocrine status. Here, we validated an enzyme immunoassay (EIA) to non-invasively quantify fecal corticosterone metabolites (FCM) in the fossorial amphisbaenian reptile Trogonophis wiegmanni from North Africa. We supplemented animals assigned to the treatment group with corticosterone dissolved in oil applied non-invasively on the skin for several days, while control groups received the oil-alone solution. Fresh feces were collected at the end of the supplementation period, and FCM levels were quantified by an EIA. Basal FCM levels were similar for both treatments and increased at the end of the test, but FCM increased significantly more in corticosterone-treated animals. A further examination of FCM levels in a wild population of this amphisbaenian did not find overall sexual, size or seasonal differences but showed a high range of variation among individuals. This suggests that different uncontrolled intrinsic or local environmental variables might increase the circulating glucocorticoid levels of different individuals. Our results confirmed the suitability of EIA for analyzing physiological changes in FCM in this amphisbaenian species. This technique may be useful for understanding and remediating the little-explored potential stressors of the soil environment that may negatively affect the health state of fossorial reptiles.

Unwrapping broken tails: Biological and environmental correlates of predation pressure in limbless reptiles.

Studying species interactions in nature often requires elaborated logistics and intense fieldwork. The difficulties in such task might hinder our ability to answer questions on how biotic interactions change with the environment. Fortunately, a workaround to this problem lies within scientific collections. For some animals, the inspection of preserved specimens can reveal the scars of past antagonistic encounters, such as predation attempts. A common defensive behaviour that leaves scars on animals is autotomy, the loss of a body appendage to escape predation. By knowing the collection site of preserved specimens, it is possible to assess the influence of organismal biology and the surrounding environment in the occurrence of autotomy. We gathered data on tail loss for 8189 preserved specimens of 33 snake and 11 amphisbaenian species to investigate biological and environmental correlates of autotomy in reptiles. We applied generalized linear mixed effect models to evaluate whether body size, sex, life-stage, habitat use, activity pattern, biome, tropicality, temperature and precipitation affect the probability of tail loss in limbless reptiles. We observed autotomy in 23.6% of examined specimens, with 18.7% of amphisbaenian and 33.4% of snake specimens showing tail loss. The probability of tail loss did not differ between snakes and amphisbaenians, but it was higher among large-sized specimens, particularly in adults and females. Chance of tail loss was higher for diurnal and arboreal species, and among specimens collected in warmer regions, but it was unaffected by biome, precipitation, and tropicality. Autotomy in limbless reptiles was affected by size-dependent factors that interplay with ontogeny and sexual dimorphism, although size-independent effects of life-stage and sex also shaped behavioural responses to predators. The increase in probability of tail loss with verticality and diurnality suggests a risk-balance mechanism between species habitat use and activity pattern. Although autotomy is more likely in warmer regions, it seems unrelated to seasonal differences in snakes and amphisbaenians activity. Our findings reveal several processes related to predator-prey interactions involving limbless reptiles, demonstrating the importance of scientific collections to unveil ecological mechanisms at different spatio-temporal scales.

Sex-dependent divergence in asymmetrical reproductive tract morphology between two closely-related amphisbaenian species (Squamata: Amphisbaenidae)

Abstract Comparing reproductive tract morphology between closely-related species may reveal mechanisms and processes leading to reproductive isolation and cladogenesis. Differences in external morphology are often inconspicuous between closely-related Neotropical species, and tissue samples for DNA sequencing are usually scarce for fossorial organisms such as amphisbaenians. Therefore, comparing characters of the reproductive tract between closely related amphisbaenians may be a viable alternative to understand processes by which evolutionary lineages have diverged morphologically from common ancestors. In this study we used multivariate ordination to compare reproductive tract morphology between two closely-related Amphisbaenidae species (Amphisbaena anaemariae and A. silvestrii), which are morphologically similar, and phylogenetically closely related. We tested the hypothesis that interspecific divergence in the reproductive tract may explain mechanisms and processes of reproductive divergence leading to evolutionary divergence. Our results suggest that divergence between two closely related Amphisbaenidae species may be linked with reproductive isolation caused by morphological differences in the reproductive tract. However, the levels of divergence detected varied between sexes and sides of the body on which the variables were measured, with vas deferens length, testis length and diameter and gonad-cloaca length as the determining variables differencing species. Although our findings must be validated by DNA-based analysis, this study provides insights into evolutionary processes based on reproductive divergence mechanisms in organisms for which sampling is hindered by fossoriality.

Serra do Navio, Guiana Shield lowland area, Brazil: a region with high diversity of Squamata

The Guiana Region is the area bordered by the Orinoco and Negro rivers to the west, by the Amazonas River to the south and by the Atlantic Ocean to the north and east. This area is a biogeographic unit known as the Guiana Shield, with a variety of landscapes. Located in the extreme north of Brazil, in the Guiana Shield lowlands, the state of Amapa presents great diversity of habitats. In this study we provide composition and diversity data of the Squamata from Serra do Navio (SN) region, in the northeastern part of the state of Amapa, Brazil, a lowland area of the Guiana Shield. The species list was based on data obtained from herpetological collections and collection expeditions carried out at 10 sites in the municipalities of Pedra Branca do Amapari and Serra do Navio. We consider literature data from 14 sites and SN data to compare the composition of herpetofauna between the lowland and highland areas in the Brazilian Amazon. We recorded 95 species, including 57 snakes, 36 lizards, and two species of amphisbaenians. Atractus aboiporu, A. trefauti, and Erythrolamprus rochai were described from the data collected in this study. The Squamata community of SN consists mainly of diurnal lizards and nocturnal snakes, with terrestrial and cryptozoic habits, present in pristine and altered environments. The most abundant species of lizard and snake were Loxopholis guianense and Atractus latifrons, respectively. The SN region has 17 exclusive Squamata species, with a fauna similar to the Tumucumaque Mountains and northern Para sites, geographically closer regions with similar altitudes.

LIZARDS AND AMPHISBAENIANS OF CATAGUASES, MINAS GERAIS, SOUTHEASTERN BRAZIL

The 'Zona da Mata' of Minas Gerais, southeastern Brazil, has less than 10% of remaining native vegetation and is home of a rich herpetofauna, still poorly surveyed. We present the results of an assessment of lizard and amphisbaenian species at Atlantic Forest fragments in the municipality of Cataguases, state of Minas Gerais, from 2009 to 2013. We used pitfall traps, occasional encounters, and local collectors, besides a literature review of records from Cataguases and neighboring cities. A total of 15 species in 12 families were found, three of them endemic to the Atlantic Forest ( Ecpleopus gaudichaudi , Enyalius boulengeri , and Gymnodactylus darwinii ). We also present a dichotomous key for identification of lizards and amphisbaenians of Cataguases.

Anatomical study of the skull of amphisbaenian Diplometopon zarudnyi (Squamata, Amphisbaenia).

This study investigates the amphisbaenian species skull which includes cranium, lower jaw and hyoid apparatus. The medial dorsal bones comprise the premaxilla, nasal, frontal and parietal. The premaxilla carries a large medial tooth and two lateral ones. The nasals are paired bones and separated by longitudinal suture. Bones of circumorbital series are frontal, orbitosphenoid and maxilla. The occipital ring consists of basioccipital, supraoccipital and exooccipital. Supraoccipital and basioccipital are single bones while the exo-occipitals are paired. The bones of the palate comprise premaxilla, maxilla, septomaxilla, palatine, pterygoid, ectopterygoid, basisphenoid, parasphenoid, orbitosphenoid and laterosphenoid. Prevomer and pterygoid teeth are absent. Palatine represent by two separate bones. The temporal bones are clearly visible. The lower jaw consists of the dentary, articular, coronoid, supra-angular, angular and splenial. The hyoid apparatus is represented by a Y-shaped structure. The mandible is long and is suspended from the braincase via relatively short quadrate. There is an extensive contact between the long angular and the large triangular coronoid. Thus inter-mandibular joint is bridged completely by the angular and consequently, the lower jaws are relatively rigid and kinetic. The maxillae are suspended from the braincase largely by ligaments and muscles rather than through bony articulation. In conclusion, the skull shape affects feeding strategy in Diplometopon zarudnyi. The prey is ingested and transported via a rapid maxillary raking mechanism.

Reptilia, Squamata, Amphisbaenidae, Amphisbaena fuliginosa wiedi Vanzolini, 1951: distribution extension

Recently, the predominantly Amazonian amphisbaenian species Amphisbaena fuliginosa was reported from the Cerrado biome, where its distribution is presently restricted to three localities in Goiás state and one in Minas Gerais state. Here we present new data on its distribution range in the Cerrado biome, a new record in the state of Minas Gerais and the southernmost record for the species, extending its southern distribution limit by 35 km.

Sexual Dimorphism in the North African AmphisbaenianTrogonophis wiegmanni

Abstract Sexual dimorphism in size or shape is common in many reptile species. Amphisbaenians are morphologically specialized for a fossorial life, which might constrain the evolution of sexual dimorphism. This might explain why some amphisbaenian species, but not others, show some type of sexual dimorphism. To understand the differential occurrence of sexual dimorphism in amphisbaenians, studies on a wide number of species belonging to different families and inhabiting different ecological conditions are needed. We measured several morphological variables in a population of the amphisbaenian Trogonophis wiegmanni, a representative of the little-studied family Trogonophidae from North Africa. Results show that males and females have similar body size; but for individuals of similar size, males are heavier, have longer tails, and have larger heads than do females. These differences might be explained by sexual selection, if males with larger heads had advantages in intrasexual contests, or by sexual diet d...

Notes on the Vertebrates of northern Pará, Brazil: a forgotten part of the Guianan Region, I. Herpetofauna

We discuss the herpetological results of seven expeditions to the Guianan part of Pará, which resulted in a total of 80 species of amphibians (77 frogs and three caecilians) and 95 species of reptiles (36 species of lizards, three species of amphisbaenians, 49 species of snakes, five species of chelonians and two species of caiman). We report six species new to science (three frogs, one caecilian, one lizard, one amphisbaenian), six new records for Brazil (five frogs, one caecilian) and 23 new records for Pará (13 frogs, four lizards, six snakes). For each of the new records we provide comments. Special comment is made about a large population of the toad Atelopus hoogmoedi that seems to be doing well and does not show any signs of population decline as many species of Atelopus at higher elevations do. We provide a complete list of species collected per locality containing data on endemicity, habitat, reproduction and food. For each of the seven collecting sites we provide data on richness and abundance of species. The sites are compared regarding their species composition, even though we can not say how much of the differences are due to specific habitats or geographic variation, seasonal variation or sampling deficiency. We synonymised the Bufonid Rhinella martyi with Bufo margaritifer and selected a lectotype for Rana margaritifera in order to resolve the problems about this name.

Sexual Dimorphism in Leposternon microcephalum and L. wuchereri (Squamata: Amphisbaenidae) from Minas Gerais, Southeastern Brazil

We present data about sexual dimorphism of two amphisbaenian species, Leposternon microcephalum and Leposternon wuchereri. Specimens were collected during faunal rescues in the course of the flooding process of four different hydroelectric dams, Santa Clara, Funil, Candonga and Ponte Hydroelectrics, at the Minas Gerais state, southeastern Brazil. Both species exhibited sexual dimorphism for different morphometric variables. While males of L. microcephalum have wider heads than conspecific females, males of L. wuchereri have wider, longer and taller heads than females but are smaller in body size.

Origin of tropical American burrowing reptiles by transatlantic rafting

Populations of terrestrial or freshwater taxa that are separated by oceans can be explained by either oceanic dispersal or fragmentation of a previously contiguous land mass. Amphisbaenians, the worm lizards (approx. 165 species), are small squamate reptiles that are uniquely adapted to a burrowing lifestyle and inhabit Africa, South America, Caribbean Islands, North America, Europe and the Middle East. All but a few species are limbless and they rarely leave their subterranean burrows. Given their peculiar habits, the distribution of amphisbaenians has been assumed to be primarily the result of two land-mass fragmentation events: the split of the supercontinent Pangaea starting 200 Myr ago, separating species on the northern land mass (Laurasia) from those on the southern land mass (Gondwana), and the split of South America from Africa 100 Myr ago. Here we show with molecular evidence that oceanic dispersal-on floating islands-played a more prominent role, and that amphisbaenians crossed the Atlantic Ocean in the Eocene (40 Myr ago) resulting in a tropical American radiation representing one-half of all known amphisbaenian species. Until now, only four or five transatlantic dispersal events were known in terrestrial vertebrates. Significantly, this is the first such dispersal event to involve a group that burrows, an unexpected lifestyle for an oceanic disperser.

Life Underground: Food Habits and Reproductive Biology of Two Amphisbaenian Species from Southern Africa

Examination and dissection of 216 museum specimens of two species of amphisbaenians (the shovel-snouted Monopeltis anchietae and round-headed Zygaspis quadrifrons) from southern Africa provided data on morphology, sexual dimorphism, reproduction, and dietary habits. The two species differed considerably in absolute size, in body proportions (eg, head width relative to snout-vent length), and in the degree of sexual dimorphism in these traits. In the relatively heavy-bodied Monopeltis both sexes attained similar body lengths, but females had wider heads than conspecific males. Conversely, in the thin-bodied Zygaspis, females attained larger body sizes than conspecific males, and there was no sexual dimorphism in head size. Clutch sizes were small in both species (means of 2.4 neonates in Monapeltis, 3.3 eggs in Zygaspis) and were not correlated with maternal body size. Termites were the most common prey far both taxa, but a wide variety of other soft-bodied invertebrates (beetle larvae, caterpillars) was also consumed. The two species differed in dietary composition, mean prey size, and in the numbers of prey items per stomach. Stomachs of Monopeltis contained more prey items than stomachs of Zygaspis (means of 72.2 versus 13.0 prey items) and prey ingested by Monopeltis were larger than those of Zygaspis. In Monopeltis, there was a significant positive correlation between predator size and prey number, but larger lizards continued to feed on relatively small prey. The reverse pattern was found in Zygaspis. The substantial differences in trophic biology between these two taxa and other sympatric fossorial reptiles, suggest that adaptations to fossoriality do not constrain ecological diversity within burrowing squamates.

Epidermal glands in Squamata: morphology and histochemistry of the pre-cloacal glands in Amphisbaena alba (Amphisbaenia)

Pre-cloacal glands occur in some species of amphisbaenians. Although these glands are important in systematics, their biology and chemistry are little known. The pre-cloacal glands of Amphisbaena alba are of the holocrine type. They are made up of a glandular body and a duct. The glandular body is conical to elongate and is formed of clongatc lobules separated one from another by collagen septa. Each lobule is composed, at its periphery, of germinative cells, and within of polyhedral secretory cells, of different degrees of differentiation. The germinative cells, set on a basal lamina, are basophilic and their cytoplasm is fairly electron dense. The polyhedral cells display bulky cytoplasm, filled with spherical granules, wrapped in membranes and differing in their electron densities. Towards the lumen of the gland, these granules are increasingly eosinophilic and have an affinity for orange G. The secretion is discharged into the duct leading to the pore, which is situated in the central region of the scale. This secretion shows positive histochemical results for mucopolysaccharides and proteins. The similarity between the epidermal glands of lizards and those of A. alba raises the suggestion that the glands have equivalent functions, possibly in the course of intra- or interspecific communication.

The ear in Amphisbaenia (Reptilia); further anatomical observations

The anatomy of the ear, and especially of the sound‐receptive and conductive system, was studied in nine species of amphisbaenians. In all species a region of skin is used as the sound‐receptive surface, and the vibrations are transmitted along a columellar apparatus consisting of cartilage and bone that expands to form a footplate in the oval window of the cochlea. In all species but one the receptive skin area is on the face; in the form Bipes biporus it is in the region of the neck constriction.The structures of the inner ear present a fairly uniform pattern, except for species variations of nearly four‐fold in the size of the hair‐cell population. The amphisbaenian extracolumella is shown to be an epihyal and not homologous to the structure of the same name in lizards.

Defensive Tail Display by Snakes and Amphisbaenians

Seventy-six species of snakes and 2 species of amphisbaenians are reported to display the tail so that it becomes unusually conspicuous. This behavior is ordinarily a response to stress, such as a sudden tactile stimulus, and is probably an antipredator strategy. The snakes can be placed in 3 groups on the basis of coloration and caudal morphology. (1) Five species are obscurely patterned or unicolored and have short tails with blunt tips. (2) Fifty-four species have contrasting or brightly colored tails without stout, blunt tips. (3) Seveeen species have either blunt, brightly colored tails or tapered, dull colored tails. Display is correlated with a brightly colored, autotomizeable tail in one amphisbaenian and with a blunt, heavily reinforced tail tip in another. A study of injuries on the tails of 52 Eryx johnii and 63 Calabaria reinhardtii suggests that these snakes display their blunt tails to misdirect the attacks of predators. Skeletal peculiarities of several boids (Charina and Eryx) and of Amphisbaena alba might be adaptations for this function of tail display. The injury data for 156 pipe snakes (Cylindrophis rufus) imply that misdirection of attack is not an important function of the display of this brightly colored species. Bright colors associated with the tail displays of many snakes and of A. fuliginosa might serve as intimidating devices, aposematic signals, or mimetic signals. The display of A. fuliginosa probably also facilitates caudal autotomy. Different functions of tail display need not, of course, be mutually exclusive. A comprehensive bibliography of tail display behavior, new information for many species, a brief discussion of terminology, speculation on the origins of tail displays, and suggestions for future investigations are also presented.