Histological aspects of the renal sexual segment of Brazilian snakes of the Boidae family.

Snakes represent a wide and diverse group of species and have anatomical particularities, such as the renal sexual segment (RSS), a structure located in the kidneys and formed from the hypertrophy of the urinary ducts and nephrons. This study aims at describing the histological aspects of the RSS of Boa constrictor, Epicrates cenchria and Corallus hortulanus, all of which are Brazilian snake species from the Boidae family. The reproductive system and kidneys of five male specimens of E. cenchria, three male specimens of C. hortulanus and two male specimens of B. constrictor were obtained. Tissue samples were processed histologically and different stains used (Toluidine Blue, Alcian Blue and Periodic Acid Schiff). The histological evaluation of the RSS of E. cenchria, C. hortulanus and B. constrictor shows that the RSS in these species varies when comparing individuals in the reproductive period with those which are not. It also allows for the observation of the segment's secretory activity in animals in the reproductive stage (mature sperm in the lumen of the seminiferous tubules) as well as in those which are not. Finally, the histological evaluation also reveals the variation of the secretion product in individuals in the reproductive period, in those which are not, and also among individuals within the same reproductive stage.

Malformations of the sacculus and the semicircular canals in spider morph pythons.

Spider morph ball pythons are a frequently-bred designer morph with striking alterations of the skin color pattern. We created high-resolution µCT-image series through the otic region of the skulls, used 3D-reconstruction software for rendering anatomical models, and compared the anatomy of the semicircular ducts, sacculus and ampullae of wildtype Python regius (ball python) with spider morph snakes. All spider morph snakes showed the wobble condition (i.e., twisting movements of the head, impaired locomotion, difficulty striking or constricting prey items). We describe the inner ear structures in wildtype and spider morph snakes and report a deviant morphology of semicircular canals, ampullae and sacculus in the latter. We also report about associated differences in the desmal skull bones of spider morph snakes, which were characterized by wider semicircular canals, ampullae widened and difficult to discern in µCT, a deformed crus communis, and a small sacculus with a highly deviant X-ray morphology as compared to wildtype individuals. We observed considerable intra- and interindividual variability of these features. This deviant morphology in spider morph snakes could easily be associated with an impairment of sense of equilibrium and the observed neurological wobble condition. Limitations in sample size prevent statistical analyses, but the anatomical evidence is strong enough to support an association between the wobble condition and a malformation of the inner ear structures. A link between artificially selected alterations in pattern and specific color design with neural-crest associated developmental malformations of the statoacoustic organ as known from other vertebrates is discussed.

Phylogeography, historical demography and systematics of the world's smallest pythons (Pythonidae, Antaresia).

Advances from empirical studies in phylogeography, systematics and species delimitation highlight the importance of integrative approaches for quantifying taxonomic diversity. Genomic data have greatly improved our ability to discern both systematic diversity and evolutionary history. Here we combine analyses of mitochondrial DNA sequences, thousands of genome-wide SNPs and linear and geometric morphometrics on Antaresia, a clade of four currently recognised dwarf pythons from Australia and New Guinea (Antaresia childreni, A. stimsoni, A. maculosa and A. perthensis). Our integrative analyses of phylogenetics, population structure, species delimitation, historical demography and morphometrics revealed that the true evolutionary diversity is not well reflected in the current appraisal of the diversity of the group. We find that Antaresia childreni and A. stimsoni comprise a widespread network of populations connected by gene flow and without evidence of species-level divergence among them. However, A. maculosa shows considerable genetic structuring which leads us to recognise two subspecies in northeastern Australia and a new species in Torres Strait and New Guinea. These two contrasting cases of over and under estimation of diversity, respectively, illustrate the power of thorough integrative approaches into understanding evolution of biodiversity. Furthermore, our analyses of historical demographic patterns highlight the importance of the Kimberley, Pilbara and Cape York as origins of biodiversity in Australia.

Linking Tooth Shape to Strike Mechanics in the Boa constrictor.

Snakes, with the obvious exception of the fangs, are considered to lack the regional specialization of tooth shape and function which are exemplified by mammals. Recent work in fishes has suggested that the definition of homodont and heterodont are incomplete without a full understanding of the morphology, mechanics, and behavior of feeding. We investigated this idea further by examining changes in tooth shape along the jaw of Boa constrictor and integrating these data with the strike kinematics of boas feeding on rodent prey. We analyzed the shape of every tooth in the skull, from a combination of anesthetized individuals and CT scanned museum specimens. For strike kinematics, we filmed eight adult boas striking at previously killed rats. We determined the regions of the jaws that made first contact with the prey, and extrapolated the relative positions of those teeth at that moment. We further determined the roles of all the teeth throughout the prey capture process, from the initiation of the strike until constriction began. We found that the teeth in the anterior third of the mandible are the most upright, and that teeth become progressively more curved posteriorly. Teeth on the maxilla are more curved than on the mandible, and the anterior teeth are more linear or recurved than the posterior teeth. In a majority of strikes, boas primarily made contact with the anterior third of the mandible first. The momentum from the strike caused the upper jaws and skull to rotate over the rat. The more curved teeth of the upper jaw slid over the rat unimpeded until the snake began to close its jaws. In the remaining strikes, boas made contact with the posterior third of both jaws simultaneously, driving through the prey and quickly retracting, ensnaring the prey on the curved posterior teeth of both jaws. The curved teeth of the palatine and pterygoid bones assist in the process of swallowing.

Two-dimensional and doppler echocardiographic evaluation in twenty-one healthy Python regius.

Echocardiographic evaluation is a diagnostic tool for the in vivo diagnosis of heart diseases. Specific and unique anatomical characteristics of the ophidian heart such as the single ventricular cavity, a tubular sinus venosus opening into the right atrium, the presence of three arterial trunks and extreme mobility in the coelomic cavity during the cardiac cycle directly affect echocardiographic examination. Twenty-one awake, healthy ball pythons (Python regius) were analysed based on guidelines for performing echocardiographic examinations. Imaging in the sagittal plane demonstrated the caudal vena cava, sinus venosus valve (SVV) and right atrium and the various portions of the ventricle, horizontal septum, left aortic arch and pulmonary artery. Transverse imaging depicted the spatial relationship of the left and right aortic arches, the pulmonary artery and the horizontal septum. Basic knowledge of cardiac blood flow in reptiles is necessary to understand the echocardiographic anatomy. The flow of the arterial trunks and SVV was analysed using pulsed-wave Doppler based on the approach used for humans and companion mammals. The walls and diameters of the cavum arteriosum, cavum venosum and cavum pulmonale were also evaluated. This study should improve the veterinarian's knowledge of ophidian heart basal physiology and contribute to the development of cardiology in reptiles.

Phylogenomics, biogeography and taxonomic revision of New Guinean pythons (Pythonidae, Leiopython) harvested for international trade.

The large and enigmatic New Guinean pythons in the genus Leiopython are harvested from the wild to supply the international trade in pets. Six species are currently recognized (albertisii, biakensis, fredparkeri, huonensis, meridionalis, montanus) but the taxonomy of this group has been controversial. We combined analysis of 421 nuclear loci and complete mitochondrial genomes with morphological data to construct a detailed phylogeny of this group, understand their biogeographic patterns and establish the systematic diversity of this genus. Our molecular genetic data support two major clades, corresponding to L. albertisii and L. fredparkeri, but offer no support for the other four species. Our morphological data also only support two species. We therefore recognize L. albertisii and L. fredparkeri as valid species and place L. biakensis, L. meridionalis, L. huonensis and L. montanus into synonymy. We found that L. albertisii and L. fredparkeri are sympatric in western New Guinea; an atypical pattern compared to other Papuan species complexes in which the distributions of sister taxa are partitioned to the north and south of the island's central mountain range. For the purpose of conservation management, overestimation of species diversity within Leiopython has resulted in the unnecessary allocation of resources that could have been expended elsewhere. We strongly caution against revising the taxonomy of geographically widespread species groups when little or no molecular genetic data and only small morphological samples are available.

Anatomic-radiographic aspects and gastrointestinal transit time in Boa constrictor amarali Stull, 1932 (Squamata, Boidae) / [Aspectos anátomo-radiográficos e tempo de trânsito gastrointestinal em jiboia-cinzenta Boa constrictor amarali Stull, 1932 (Squamata, Boidae)]

The goal of this study was to describe the gastrointestinal transit technique in the Boa constrictor amarali. For that purpose, we obtained simple radiographic images of seven serpents, subsequently administering a 25mL/kg dose of barium sulfate and establishing a radiographic sequence at the following times: 5 minutes; 1, 2, 3, 6, 9, 24, 48, 72 and 96 hours, extending to 120 and 126 hours for one animal. The mean esophageal transit was 26.71±19.48 hours; the mean gastric filling time was 28.57±27.22 minutes and the emptying time was 60±12 hours; the mean filling time of the contrast medium in the small intestine was 3±2.16 hours and the emptying time was 97±15.65 hours. We also obtained the mean filling time of the large intestine, which was 40±11.31 hours. We found that the mean passage time of the contrast medium through the cranial gastrointestinal tract - until the complete elimination of barium sulfate from the small intestine -was 97±15.65 hours. In addition to determining the gastrointestinal transit time, the technique used allowed for the morphological identification of the alimentary canal.(AU)

O objetivo deste trabalho foi descrever a técnica de trânsito gastrointestinal em Boa constrictor amarali. Para tanto, foram obtidas radiografias simples de sete serpentes, e, subsequentemente a essas, foi administrado sulfato de bário na dose de 25mL/kg. A partir disso, foi estabelecida a sequência radiográfica nos seguintes tempos: cinco minutos; uma, duas, três, seis, nove, 24, 48, 72 e 96 horas, e em um animal estendeu-se para 120 e 126 horas. O trânsito esofágico médio foi de 26,71±19,48 horas, o tempo médio de preenchimento gástrico foi de 28,57±27,22 minutos, e o esvaziamento de 60±12 horas; a média de tempo de enchimento do meio de contraste no intestino delgado foi de 3±2,16 horas e, por fim, o esvaziamento foi de 97±15,65 horas, e ainda obteve-se o tempo médio de enchimento do intestino grosso igual a 40±11,31 horas. Desse modo, verificou-se que a média do tempo de passagem do contraste pelo trato gastrointestinal cranial - até a completa eliminação do sulfato de bário do intestino delgado - foi de 97±15,65 horas. Além da determinação do tempo de trânsito gastrointestinal, a técnica empregada permitiu a identificação morfológica do canal alimentar.(AU)

Phylogenomics, Biogeography, and Morphometrics Reveal Rapid Phenotypic Evolution in Pythons After Crossing Wallace's Line.

Ecological opportunities can be provided to organisms that cross stringent biogeographic barriers towards environments with new ecological niches. Wallace's and Lyddeker's lines are arguably the most famous biogeographic barriers, separating the Asian and Australo-Papuan biotas. One of the most ecomorphologically diverse groups of reptiles, the pythons, is distributed across these lines, and are remarkably more diverse in phenotype and ecology east of Lydekker's line in Australo-Papua. We used an anchored hybrid enrichment approach, with near complete taxon sampling, to extract mitochondrial genomes and 376 nuclear loci to resolve and date their phylogenetic history. Biogeographic reconstruction demonstrates that they originated in Asia around 38-45 Ma and then invaded Australo-Papua around 23 Ma. Australo-Papuan pythons display a sizeable expansion in morphological space, with shifts towards numerous new adaptive optima in head and body shape, coupled with the evolution of new micro-habitat preferences. We provide an updated taxonomy of pythons and our study also demonstrates how ecological opportunity following colonization of novel environments can promote morphological diversification in a formerly ecomorphologically conservative group. [Adaptive radiation; anchored hybrid enrichment; biogeography; morphometrics; snakes.].

TWO-DIMENSIONAL ECHOCARDIOGRAPHIC MEASUREMENTS IN THE BALL PYTHON (PYTHON REGIUS).

Reptiles can suffer from infectious and noninfectious cardiac pathologies, requiring the need for standardized diagnostic approaches and reference intervals. Despite the popularity of ball pythons (Python regius) as pets, echocardiographic measurements are unknown in this species. Twenty healthy adult ball pythons were evaluated to identify imaging planes, establish reference intervals for cardiac assessment by two-dimensional echocardiography, and study the effects of sex, body length, and body mass on heart rate, fractional shortening, and vascular, atrial, and ventricular dimensions. Echocardiography was performed under manual restraint. Most cardiac measurements were positively correlated with body length and mass, with the strongest correlation between ventricular end-systolic measurements and body length. The only significant difference found between sexes was for right and left atrial lengths. This study provides guidelines and reference intervals for two-dimensional echocardiographic measurements in adult healthy ball pythons.

TOMOGRAPHIC ATTENUATION OF THE HEPATIC PARENCHYMA OF ADULT FREE-RANGING AND CAPTIVE BOAS (BOA CONSTRICTOR).

Improperly managed care conditions for reptiles can lead to clinical problems, including those of nutritional origin. A diagnostic tool to aid in the assessment of hepatic lipidosis is warranted. Evaluation of attenuation using quantitative computed tomography has a variety of indications in animals and permits the standardization of hepatic computed tomography (CT) reference values, aiding in the diagnosis of lipidosis. The objective of this paper was to estimate hepatic quantitative CT reference values for boas because of the lack of data in the literature for this species. CT scans were performed in 13 boas (Boa constrictor constrictor): 5 under managed care and 8 that were free ranging. Results show that the mean hepatic attenuation in the captive boa group was well below the mean for the free-ranging animals (P < 0.05) with respective values of 48.78 ± 6.57 and 61.76 ± 7.11 HU. These results suggest an influence of managed care on liver attenuation. These results were observed despite the lack of clinical or laboratory changes. This imaging technique is useful to detect early hepatic changes; however, clinical relevance is unknown at this point. Further studies and standardization of species-specific values for hepatic quantitative CT would contribute to better understanding of the physiologic, physiopathologic, environmental, and nutritional processes.

Identification and mapping of real acupoints in the anatomical topography of Boa constrictor / Identificação e mapeamento de acupontos reais na topografia anatômica de Boa constrictor

Abstract Acupuncture is a therapy of the traditional Chinese medicine technique, which over the years has been widespread in the West. Defined as a needle-point treatment technique (acupoints), exactly preconfigured in the body to produce a specific physiological reaction to restore the balance between the function of conflicting states and homeostasis, alternating states of energy and thus maintain the ideal organ and body organization. Thus, the objective of this study was to map and describe the main points of acupuncture in the species Boa constrictor , and their indications to promote the balance of this species. The unprecedented result of the mapping was the discovery of specific acupoints with individual location indications without distribution in specific meridians and dispersedly distributed in the body.

Resumo A acupuntura é uma técnica terapêutica da Medicina Tradicional Chinesa, que ao longo dos anos tem sido muito difundida no Ocidente. Definida como uma técnica de tratamento com inserção de agulhas em pontos (acupontos) exatamente pré-estabelecidos sobre o organismo, para produzir uma reação fisiológica específica com o intuito de restabelecer o equilíbrio entre estados contraditórios de função e a homeostase, alternando os estados de energia e com isto mantendo a organização do órgão e do organismo. Com isso, o objetivo do presente trabalho foi mapear e descrever os principais pontos de acupuntura nas espécies Boa constrictore suas indicações para promover o equilíbrio dessa espécie. O resultado inédito do mapeamento foi à descoberta de pontos de acupuntura específicos com indicações de localização individuais sem distribuição em meridianos específicos e dispersamente distribuídos no corpo.

Identification and mapping of real acupoints in the anatomical topography of Boa constrictor.

Acupuncture is a therapy of the traditional Chinese medicine technique, which over the years has been widespread in the West. Defined as a needle-point treatment technique (acupoints), exactly preconfigured in the body to produce a specific physiological reaction to restore the balance between the function of conflicting states and homeostasis, alternating states of energy and thus maintain the ideal organ and body organization. Thus, the objective of this study was to map and describe the main points of acupuncture in the species Boa constrictor , and their indications to promote the balance of this species. The unprecedented result of the mapping was the discovery of specific acupoints with individual location indications without distribution in specific meridians and dispersedly distributed in the body.

The rhinoceros among Serpents: Comparative anatomy and experimental biophysics of Calabar burrowing python (Calabaria reinhardtii) skin.

The Calabar burrowing python (Calabaria reinhardtii) has a unique combination of marked thickness of the integumentary layers, a highly organized lamellate arrangement of the dermal collagen bundles, and a reduction in the size of the interscale hinge region of the integument. Biomechanical testing demonstrates that the skin of C. reinhardtii is more resistant to penetration than the skin of other snakes. The laminar arrangement of the collagen bundles provides for penetrative resistance, even while maintaining the flexibility characteristic of snake skin. Considering the life history of this species, it is hypothesized that the specialized integument of C. reinhardtii is a passive defensive mechanism against penetrative bites from maternal rodents and predators.

Snake spectacle vessel permeability to sodium fluorescein.

OBJECTIVE: Assess vascular permeability of the snake spectacle to sodium fluorescein during resting and shedding phases of the ecdysis cycle. ANIMAL STUDIED: Ball python (Python regius). PROCEDURES: The snake was anesthetized, and spectral domain optic coherence tomography was performed prior to angiographic procedures. An electronically controlled digital single-lens reflex camera with a dual-head flash equipped with filters suitable for fluorescein angiography was used to make images. Sodium fluorescein (10%) solution was administered by intracardiac injection. Angiographic images were made as fluorescein traversed the vasculature of the iris and spectacle. Individually acquired photographic frames were assessed and sequenced into pseudovideo image streams for further evaluation CONCLUSIONS: Fluorescein angiograms of the snake spectacle were readily obtained. Vascular permeability varied with the phase of ecdysis. Copious leakage of fluorescein occurred during the shedding phase. This angiographic method may provide diverse opportunities to investigate vascular aspects of snake spectacle ecdysis, dysecdysis, and the integument in general.

Morphology of the snake spectacle reflects its evolutionary adaptation and development.

BACKGROUND: Covering the eye of all snakes is a transparent integumental structure known as the spectacle. In order to determine variations in spectacle thickness among species, the spectacles of 217 alcohol-preserved museum specimens of 44 species belonging to 14 different families underwent optical coherence tomography (OCT) to measure spectacular thickness. Multivariable analyses were made to determine whether family, activity period (diurnal/nocturnal) and habitat (arboreal/terrestrial/fossorial/aquatic) influenced spectacle thickness. RESULTS: The thinnest spectacles in absolute terms were found in the Usambara bush viper (Viperidae) with a thickness of 74 ± 9 µm and the absolute thickest spectacle was found in the red-tailed pipe snake (Cylindrophiidae) which had a spectacle thickness of 244 ± 57 µm. Fossorial and aquatic snakes had significantly thicker spectacles than arboreal and terrestrial snakes. When spectacle thickness was correlated to eye size (horizontal spectacle diameter), Gray's earth snake (Uropeltidae) had the lowest ratio (1:7) and the cottonmouth (Viperidae) had the highest ratio (1:65). Multivariable and phylogenetic analyses showed that spectacular thickness could be predicted by taxonomic family and habitat, but not activity period. CONCLUSION: This phylogenetically broad systematic study of the thickness of the snake spectacle showed that spectacular thickness varies greatly across snake species and may reflect evolutionary adaptation and development.

A validation of 11 body-condition indices in a giant snake species that exhibits positive allometry.

Body condition is a gauge of the energy stores of an animal, and though it has important implications for fitness, survival, competition, and disease, it is difficult to measure directly. Instead, body condition is frequently estimated as a body condition index (BCI) using length and mass measurements. A desirable BCI should accurately reflect true body condition and be unbiased with respect to size (i.e., mean BCI estimates should not change across different length or mass ranges), and choosing the most-appropriate BCI is not straightforward. We evaluated 11 different BCIs in 248 Burmese pythons (Python bivittatus), organisms that, like other snakes, exhibit simple body plans well characterized by length and mass. We found that the length-mass relationship in Burmese pythons is positively allometric, where mass increases rapidly with respect to length, and this allowed us to explore the effects of allometry on BCI verification. We employed three alternative measures of 'true' body condition: percent fat, scaled fat, and residual fat. The latter two measures mostly accommodated allometry in true body condition, but percent fat did not. Our inferences of the best-performing BCIs depended heavily on our measure of true body condition, with most BCIs falling into one of two groups. The first group contained most BCIs based on ratios, and these were associated with percent fat and body length (i.e., were biased). The second group contained the scaled mass index and most of the BCIs based on linear regressions, and these were associated with both scaled and residual fat but not body length (i.e., were unbiased). Our results show that potential differences in measures of true body condition should be explored in BCI verification studies, particularly in organisms undergoing allometric growth. Furthermore, the caveats of each BCI and similarities to other BCIs are important to consider when determining which BCI is appropriate for any particular taxon.

Morpho-functional characterization of the systemic venous pole of the reptile heart.

Mammals evolved from reptile-like ancestors, and while the mammalian heart is driven by a distinct sinus node, a sinus node is not apparent in reptiles. We characterized the myocardial systemic venous pole, the sinus venosus, in reptiles to identify the dominant pacemaker and to assess whether the sinus venosus remodels and adopts an atrium-like phenotype as observed in mammals. Anolis lizards had an extensive sinus venosus of myocardium expressing Tbx18. A small sub-population of cells encircling the sinuatrial junction expressed Isl1, Bmp2, Tbx3, and Hcn4, homologues of genes marking the mammalian sinus node. Electrical mapping showed that hearts of Anolis lizards and Python snakes were driven from the sinuatrial junction. The electrical impulse was delayed between the sinus venosus and the right atrium, allowing the sinus venosus to contract and aid right atrial filling. In proximity of the systemic veins, the Anolis sinus venosus expressed markers of the atrial phenotype Nkx2-5 and Gja5. In conclusion, the reptile heart is driven by a pacemaker region with an expression signature similar to that of the immature sinus node of mammals. Unlike mammals, reptiles maintain a sinuatrial delay of the impulse, allowing the partly atrialized sinus venosus to function as a chamber.

Loss and Re-emergence of Legs in Snakes by Modular Evolution of Sonic hedgehog and HOXD Enhancers.

Limb reduction and loss are hallmarks of snake evolution. Although advanced snakes are completely limbless, basal and intermediate snakes retain pelvic girdles and small rudiments of the femur. Moreover, legs may have re-emerged in extinct snake lineages [1-5], suggesting that the mechanisms of limb development were not completely lost in snakes. Here we report that hindlimb development arrests in python embryos as a result of mutations that abolish essential transcription factor binding sites in the limb-specific enhancer of Sonic hedgehog (SHH). Consequently, SHH transcription is weak and transient in python hindlimb buds, leading to early termination of a genetic circuit that drives limb outgrowth. Our results suggest that degenerate evolution of the SHH limb enhancer played a role in reduction of hindlimbs during snake evolution. By contrast, HOXD digit enhancers are conserved in pythons, and HOXD gene expression in the hindlimb buds progresses to the distal phase, forming an autopodial (digit) domain. Python hindlimb buds then develop transitory pre-chondrogenic condensations of the tibia, fibula, and footplate, raising the possibility that re-emergence of hindlimbs during snake evolution did not require de novo re-evolution of lost structures but instead could have resulted from persistence of embryonic legs. VIDEO ABSTRACT.

Parallel selective pressures drive convergent diversification of phenotypes in pythons and boas.

Pythons and boas are globally distributed and distantly related radiations with remarkable phenotypic and ecological diversity. We tested whether pythons, boas and their relatives have evolved convergent phenotypes when they display similar ecology. We collected geometric morphometric data on head shape for 1073 specimens representing over 80% of species. We show that these two groups display strong and widespread convergence when they occupy equivalent ecological niches and that the history of phenotypic evolution strongly matches the history of ecological diversification, suggesting that both processes are strongly coupled. These results are consistent with replicated adaptive radiation in both groups. We argue that strong selective pressures related to habitat-use have driven this convergence. Pythons and boas provide a new model system for the study of macro-evolutionary patterns of morphological and ecological evolution and they do so at a deeper level of divergence and global scale than any well-established adaptive radiation model systems.

Sex allocation and secondary sex ratio in Cuban boa (Chilabothrus angulifer): mother's body size affects the ratio between sons and daughters.

Secondary sex ratios of animals with genetically determined sex may considerably deviate from equality. These deviations may be attributed to several proximate and ultimate factors. Sex ratio theory explains some of them as strategic decisions of mothers improving their fitness by selective investment in sons or daughters, e.g. local resource competition hypothesis (LRC) suggests that philopatric females tend to produce litters with male-biased sex ratios to avoid future competition with their daughters. Until now, only little attention has been paid to examine predictions of sex ratio theory in snakes possessing genetic sex determination and exhibiting large variance in allocation of maternal investment. Cuban boa is an endemic viviparous snake producing large-bodied newborns (∼200 g). Extremely high maternal investment in each offspring increases importance of sex allocation. In a captive colony, we collected breeding records of 42 mothers, 62 litters and 306 newborns and examined secondary sex ratios (SR) and sexual size dimorphism (SSD) of newborns. None of the examined morphometric traits of neonates appeared sexually dimorphic. The sex ratio was slightly male biased (174 males versus 132 females) and litter sex ratio significantly decreased with female snout-vent length. We interpret this relationship as an additional support for LRC as competition between mothers and daughters increases with similarity of body sizes between competing snakes.