Hematology of Liolaemus pacha (Iguania: Liolaemidae) and its relationship with mite infestation, reproductive period and body condition.

Variations in hematological profile in reptiles can be caused by multiple factors, including parasites presence. Our goals were to identify and morphologically describe blood cells of Liolaemus pacha and analyze their relationship with sex, body condition, individual reproductive/post-reproductive period and mite infestation. Blood smear analyses do not indicate the presence of hemoparasites, suggesting that the mites Neopterygosoma do not serve as vectors for these organisms, as has been proposed for other genera of ectoparasitic mites. In post-reproductive period, there was a reduction in specimens' body condition and a higher leukocyte count in uninfected lizards. This could be a consequence of the testosterone effects, in higher concentration during the reproductive season, which can increase the metabolic rate, decreasing feeding rate. Infested and non-infested lizards showed no differences in body condition, as well as in leukocyte count, hence the host's immune system could be developing infestation tolerance. Infested specimens had a higher count of monocytes, thrombocytes, heterophils and lymphocytes. Based on cells function, mites' effect could be associated with inflammatory processes, allergic reactions or infectious diseases. These results suggested a complex interaction between lizards' hematological parameters and factors associated to ectoparasites or body conditions. We consider this work as a diagnostic tool for genus Liolaemus, to evaluate health quality, with relevance to the conservation or management of this lizard's genus.

The skull of the Turks and Caicos rock iguana, Cyclura carinata (Squamata: Iguanidae).

We provide a detailed and first description of the skull, hyoid apparatus, and trachea of the Turks and Caicos rock iguana, Cyclura carinata (Squamata: Iguanidae). Cyclura is a radiation of iguanas restricted to islands of the Caribbean Sea. Species of Cyclura have high rates of endemism, and all species are severely threatened with extinction. Our anatomical description of this threatened iguana is based on high-resolution computed tomography scans of one adult, one putative adult or near adult, and one juvenile specimen, and includes three-dimensional segmented renderings and visualizations. We discuss some observations of intraspecific and ontogenetic variation, and provide a brief comparison with specimens of another species of Cyclura and published descriptions of other iguanas. Our study provides a cranial osteological framework for Cyclura and augments the body of knowledge on iguana anatomy generally. Finally, we posit that our description and future studies may facilitate identification of fossil Cyclura, which could help understand the paleobiogeography of the genus.

High sugar diet alters immune function and the gut microbiome in juvenile green iguanas (Iguana iguana).

The present work aimed to study whether a high sugar diet can alter immune responses and the gut microbiome in green iguanas. Thirty-six iguanas were split into four treatment groups using a 2×2 design. Iguanas received either a sugar-supplemented diet or a control diet, and either a lipopolysaccharide (LPS) injection or a phosphate-buffered saline (PBS) injection. Iguanas were given their respective diet treatment through the entire study (∼3 months) and received a primary immune challenge 1 and 2 months into the experiment. Blood samples and cloacal swabs were taken at various points in the experiment and used to measure changes in the immune system (bacterial killing ability, lysis and agglutination scores, LPS-specific IgY concentrations), and alterations in the gut microbiome. We found that a sugar diet reduces bacterial killing ability following an LPS challenge, and sugar and the immune challenge temporarily alters gut microbiome composition while reducing alpha diversity. Although sugar did not directly reduce lysis and agglutination following the immune challenge, the change in these scores over a 24-h period following an immune challenge was more drastic (it decreased) relative to the control diet group. Moreover, sugar increased constitutive agglutination outside of the immune challenges (i.e. pre-challenge levels). In this study, we provide evidence that a high sugar diet affects the immune system of green iguanas (in a disruptive manner) and alters the gut microbiome.

Hand grab or noose pole? Evaluating the least stressful practice for capture of endangered Turks and Caicos Rock Iguanas Cyclura carinata.

As the analysis of blood metabolites has become more readily accessible thanks to the use of point-of-care analyzers, it is now possible to evaluate stress level of wild animals directly in the field. Lactate is receiving much attention as a good stress level proxy in individuals subjected to capture, manual restraint, and data sampling in the wild, and appropriate protocols to maintain lactate values low should be preferred. In this study we compare how two different capture methodologies, hand grab vs. noose pole, affect the variation of blood lactate values in Cyclura carinata iguanas when captured for sampling. We used blood lactate concentration, measured immediately upon- and 15 min after-capture, as a proxy for stress level. While the primary goal of this work is to determine the least stressful capture methodology to be favored when sampling this and other wild iguanas, we also evaluated additional baseline physiological parameters relevant to the health and disease monitoring for this species. Our results show that while initial lactate values level-out in sampled individuals after 15 min in captivity, regardless of the capture methodology, rock iguanas captured by noose pole showed significantly higher lactate concentration and increased heartbeat rate immediately after capture. While the overall health evaluation determined that all analyzed individuals were in good health, based on our results we recommend that, when possible, hand capture should be preferred over noose pole when sampling wild individuals.

Comparison between a Tail Clamp and Electrical Stimulation for Sevoflurane Minimum Anesthetic Concentration Determination in Green Iguanas (Iguana iguana).

This study aimed to compare the minimum anesthetic concentration (MAC) of sevoflurane in green iguanas using elec- trical stimulation and tail clamping as noxious stimuli. Seven adult green iguanas (Iguana iguana) weighing 580 to 1,300 g were enrolled. Each iguana was anesthetized twice after a 1-week washout period, with MAC being determined using a tail clamp (MACt) or electrical stimulation (MACe ) techniques. After sevoflurane mask induction and endotracheal intubation, the fraction of expired sevoflurane (Fe 'Sevo) was maintained at 3.1% for 15 min before noxious stimulation. In a bracketing design, the subsequent Fe'Sevo values were increased or decreased by 10% after positive or negative responses, respectively. Each targeted Fe 'Sevo was kept constant for 15 min before stimulation. In MACt, the noxious stimulus involved closing a Kelly hemostatic curved forceps to the first ratchet at the base of the tail. At the same site, in MACe, 2 30 × 0.8-mm hypodermic needles inserted 1 cm apart were connected to an electrical stimulator set to deliver 30 mA at 50 Hz at a 6.5-ms interval. The hemostat and the needles were repositioned 2 cm distally and on alternate tail sides at each stimulation round. Individual MAC was obtained when 2 consecutive crossover events occurred (a positive response preceding a negative response or vice versa), with the MAC of each group represented by the average of the individual MAC values. Median (interquartile range) values for the sevoflurane MAC did not differ significantly between groups (2.2 [2.2 to 2.8%] in MACe and 2.2 [1.8 to 3.5%] in MACt ; P = 0.812). Time to anesthesia induction, time to MAC measurement, heart rate (HR), end-tidal carbon dioxide (ET'CO2), and cloacal temperature were not different between groups. Both the tail-clamping and the electrical stimulation techniques yielded resembling sevoflurane MAC values in green iguanas, which makes the tail clamp a reliable alternative to electrical stimulation-based MAC research in this species.

CLINICAL AND PATHOLOGIC FINDINGS IN IGUANIDS WITH SODIUM URATE CHOLELITHIASIS.

Four green iguanas (Iguana iguana) and one blue iguana (Cyclura lewisi) from five facilities were diagnosed with sodium urate cholelithiasis. One case was diagnosed antemortem via ultrasonography, and the iguana underwent a choledochotomy for treatment. The other four cases were identified at necropsy. Pathologic hepatic and biliary changes were present in four of the five cases at necropsy. Histologically, four iguanas had hepatic fibrosis, three had bile duct hyperplasia, and one had cholangiohepatitis and pancreaticocholedochitis. Two iguanas had pathologic renal changes. This is the first report of sodium urate cholelithiasis in reptiles. This case series highlights the potential significant clinical disease caused by sodium urate cholelithiasis and the importance of biliary system evaluation. Further investigation is recommended to explore the pathogenesis of reptilian sodium urate cholelith formation.

Novel herpesvirus in the critically endangered Galapagos pink land iguana.

Virus surveillance in wildlife is important to understanding ecosystem health, taxonomy, and evolution. Nevertheless, viruses in reptiles, and specifically in squamates, continue to be understudied. Herein, we conducted a health assessment on the critically endangered Galapagos pink land iguana (Conolophus marthae) and the vulnerable Galapagos land iguana (Conolophus subcristatus). We collected oral and/or cloacal swabs from 47 clinically healthy iguanas and tested for adenovirus (cloacal swabs, n = 47) and herpesvirus (oral swabs, n = 45) using broad-spectrum PCRs. Two out of 38 (5.3 %) Galapagos pink land iguanas tested positive for herpesvirus, while no herpesvirus was detected in all Galapagos land iguanas (n = 7). Both herpesviral sequences were identical between them and divergent (61.9 % amino acid identity) when compared to the closest herpesvirus sequences available in GenBank/EMBL/DDBJ. The genetic distance between this and other herpesviruses is consistent with its classification as a novel virus species. All iguanas were negative for adenovirus. This is the first description of a herpesvirus in iguanas of the Galapagos islands, and the first report of a potential pathogen for the iconic Galapagos pink land iguana. Further research is needed to understand the implications of this virus in the conservation and management of one of the most endangered iguana species in the world.

Cardiovascular responses and the role of the neurohumoral cardiac regulation during digestion in the herbivorous lizard Iguana iguana.

Carnivorous reptiles exhibit an intense metabolic increment during digestion, which is accompanied by several cardiovascular adjustments responsible for meeting the physiological demands of the gastrointestinal system. Postprandial tachycardia, a well-documented phenomenon in these animals, is mediated by the withdrawal of vagal tone associated with the chronotropic effects of non-adrenergic and non-cholinergic (NANC) factors. However, herbivorous reptiles exhibit a modest metabolic increment during digestion and there is no information about postprandial cardiovascular adjustments. Considering the significant impact of feeding characteristics on physiological responses, we investigated cardiovascular and metabolic responses, as well as the neurohumoral mechanisms of cardiac control, in the herbivorous lizard Iguana iguana during digestion. We measured oxygen consumption rate (O2), heart rate (fH), mean arterial blood pressure (MAP), myocardial activity, cardiac autonomic tone, fH/MAP variability and baroreflex efficiency in both fasting and digesting animals before and after parasympathetic blockade with atropine followed by double autonomic blockade with atropine and propranolol. Our results revealed that the peak of O2 in iguanas was reached 24 h after feeding, accompanied by an increase in myocardial activity and a subtle tachycardia mediated exclusively by a reduction in cardiac parasympathetic activity. This represents the first reported case of postprandial tachycardia in digesting reptiles without the involvement of NANC factors. Furthermore, this withdrawal of vagal stimulation during digestion may reduce the regulatory range for short-term fH adjustments, subsequently intensifying the blood pressure variability as a consequence of limiting baroreflex efficiency.

Dried blood spot analysis for elements of nutritional concern as demonstrated in studies of Galápagos land iguanas (Conolophus species).

BACKGROUND: Dried blood spot (DBS) technology is valuable in providing simple means of storing blood samples from wildlife with small blood volumes. Methods designed for heavy metal analysis on DBS become more useful if extended to elements of nutritional significance. PURPOSE: (1) Development of procedures for measuring Mn, Fe, Co, Cu, Zn, Se and Mo in DBS; (2) use the designed methods in health assessments of Galápagos land iguanas (Conolophus species). PROCEDURES: Elements were measured by inductively coupled plasma/mass spectrometry (ICP-MS) following acid digestion of whole blood or DBS from the same animal for direct comparison. Study animals comprised free-ranging iguanas from separate islands in the Galápagos archipelago. MAIN FINDINGS: DBS spikes (Mn, Fe, Co, Cu, Zn, Se and Mo) demonstrated accuracy to ∼100 ppb; reporting limits were set there except for Fe and Zn which were set at 1000 ppb. Plasma samples - generally preferable for nutritional element diagnostics - were submitted from Galápagos land iguanas along with DBS as part of a large-scale health assessment. In plasma versus DBS concentration comparisons, Fe, Cu, Se and Mn correlated well with R^2 values of 0.799, 0.818, 0.896 and 0.899, respectively, and slopes ranging 0.88 - 1.3. Co and Zn showed greater scatter. Mo had insufficient points above its reporting limit and offered advantages for toxicity assessments. Bland-Altman diagrams showed flat scatter between 2x standard deviation boundaries with no undue trends except for Mn which had few points above its reporting limit. Bias, defined as the average difference [DBS - plasma] divided by the average value, was relatively low throughout, with values of - 19.3 % (Fe), - 48.7 % (Co), - 19.6 % (Cu), - 6.9 % (Zn), - 21.4 % (Se) and + 40.7 % (Mn). Normal distribution assessment of iguana Cu, Zn, Se and Fe plasma values showed unanticipated divergences between two species. CONCLUSIONS: The DBS approach for nutritional element analysis offers a suitable methodology for determining crucial elements Mn, Fe, Co, Cu, Zn, Se, and Mo in veterinary samples. Analyses of samples from Conolophus species revealed interesting divergences particularly for Cu, Zn, Se and Fe, elements generally associated with defense against oxidative stress.

Social opportunities and mate preference improve breeding success in Caribbean iguanas.

Conservation breeding of West Indian rock iguanas (Cyclura) has met with limited success historically. Many facilities witness high levels of aggression and mate incompatibility resulting in failed breeding introductions which often require animals to be separated. This may be due, in part, to lack of knowledge of how mate familiarity and preference affect reproductive outcomes in these species. We investigated whether social exposure during the pre-breeding season influenced copulation success, egg production, and breeding behaviors. Additionally, we examined whether mate preference, as determined by pre-mating dichotomous choice tests, increased these reproductive outcomes. Female rock iguanas that were socialized with males prior to breeding opportunities copulated with familiar males for longer periods of time than females that were not socialized. Socialization opportunities did not alter male reproductive success measurements or breeding behavior. Female rock iguanas introduced for mating to their preferred partners had a higher probability of successful copulations, higher average number of copulations, and less resting behavior during introductions than females mated to non-preferred males. Male mate preference had no effect on reproductive success measurements during mating introductions. These results indicate that socializing animals and providing mate choice opportunities increase breeding success of rock iguanas under managed care.

The ultrastructural features of the infundibulum of the green iguana, Iguana iguana.

The purpose of this study is to describe, in detail, the ultrastructure of the infundibulum of the sexually mature and active female green iguana, Iguana iguana. The infundibulum of five iguanas was remarkably distinct from the uterus, and was also clearly demarcated into cranial (expanded v-shaped) and caudal (tubular) divisions. Tissue samples obtained from five portions (three from the cranial division and two from the caudal division) of the infundibulum were processed conventionally for light and electron microscopy. The epithelial lining of the most anterior, middle, and posterior, parts of the cranial division displayed nonciliated cells predominantly, and occasionally ciliated cells. The numerous secretory granules in nonciliated type 1 cell found in the fimbrial aspect of the infundibulum were homogenous and deeply electron-dense, but those in the other two regions were variants of this cell type because they contained variably electron-dense secretory granules. Two main types of nonciliated cells (type 2 and its variant, type 3, as well as type 4) occurred in the epithelial lining of the caudal division of the infundibulum, but they, clearly, showed no dense secretory granules. Whereas the nonciliated type 2 cell and its variant (type 3 cell) contained large glycogen deposits, the type 4 cell lacked these deposits but its apical part contained large lipid-like droplets and, remarkably, blebbed into the duct lumen. The nonciliated cells lining the mucosal tubular glands contained highly electron-dense secretory granules, which were similar to those found in the nonciliated type 1 cell in the epithelial lining of the fimbrial part of the cranial division of the infundibulum.

Ozolaimus megatyphlon and Ozolaimus cirratus parasitizing the Iguana iguana (Linnaeus, 1758) from Marajó Island, Pará, Brasil: new occurrence and morphological redescription.

This study aimed to redescribe two species of Ozolaimus, parasites of free-living green iguanas native to Marajó Island. The gastrointestinal system of four iguana specimens was evaluated for the presence of helminths. Altogether, 12,028 nematodes were found, with a prevalence of 100%, an infection range of 780 to 7,736 nematodes, an infection intensity of 3.007, and a mean abundance of 3,007. Light microscopy and scanning electron microscopy were used to determine the species of nematodes found. The cecum was the site of infection that had the highest parasitic load. Morphologically, the nematodes were compatible with the genus Ozolaimus Dujardin, 1844, with the species Ozolaimus megatyphlon (Rudolphi, 1819) Dujardin, 1845, and Ozolaimus cirratus Linstow, 1906. Scanning electron microscopy showed the presence of small structures (serrated in Ozolaimus cirratus and rounded in Ozolaimus megatyphlon) located below the esophageal leaves. We also evidenced the phasmids in both species; this is the first record of these structures in nematodes of the genus Ozolaimus. In addition, this work expands the records on the geographic distribution of these parasites.

HELICOBACTER SCREENING OF GRAND CAYMAN BLUE IGUANA (CYCLURA LEWISI) AND NORTH ANTILLEAN SLIDER (TRACHEMYS DECUSSATA ANGUSTA) ON GRAND CAYMAN, CAYMAN ISLANDS.

The endemic Grand Cayman or blue iguana (Cyclura lewisi) is endangered. Beginning in 2015 significant morbidity and mortality occurred in captive and wild blue iguanas within Grand Cayman's Queen Elizabeth II Botanic Park (QEIIBP). Investigation identified a novel Helicobacter sp., provisionally named Helicobacter sp. Grand Cayman Blue Iguana 1 (GCBI1), as the cause. Invasive green iguanas (Iguana iguana) are believed to play a role in GCBI1 transmission to the blue iguana; however, the origin and transmission pathways have not been determined. To assess the likelihood of blue iguanas asymptomatically harboring GCBI1, in May 2022 population-level screening of captive blue iguanas at QEIIBP was conducted on half (n = 102) of the captive blue iguana population (n = 201) including half of each age class. Helicobacter sp. GCBI1 is closely related to a chelonian Helicobacter sp. and 10 sympatric wild north Antillean sliders (Trachemys decussata angusta) were sampled in October 2019. Combined choana/cloacal swabs were screened by a GCBI1-specific quantitative polymerase chain reaction (qPCR) assay. All samples were negative, suggesting that GCBI1 is not present asymptomatically in the captive blue iguana population or in north Antillean sliders. These results provide support for the hypothesis that GCBI1 is periodically introduced to captive and wild blue iguanas from another species or source.

Hirstiella spp. Infestation in A Client-Owned Iguana (Iguana Iguana) Associated With Skin Lesions on its Owner.

A green iguana (Iguana iguana) was presented for severe pruritus, dysecdysis, reduced appetite, lethargy, and the presence of dark red spots on the entire body. A pruritic dermatitis was present on the owner's arms as well. Parasitological examination (light microscopy) performed on the affected iguana, via skin scraping and acetate tape test, revealed numerous Hirstiella spp. mites. Resolution of clinical signs occurred 3 weeks after daily water bath and 3 weekly applications of a 0.25% fipronil solution (sprayed on a glove and then rubbed on the skin of the lizard) along with application of diluted fipronil (1:5 in water). This is the first case report of potential Hirstiella spp. dermatitis in an adult human. Although uncommon, Hirstiella spp. infestation should be considered as a possible differential in pruritic pet lizards specifically in cases in which the owner presents a papular dermatitis.

Formation and Replacement of Bone and Tooth Mineralized Tissues in Green Iguanas (Iguana iguana) Revealed by In-Vivo Fluorescence Marking.

Hard tissue formation patterns and rates reveal details of animal physiology, life history, and environment, but are understudied in reptiles. Here, we use fluorescence labels delivered in vivo and laser confocal scanning microscopy to study tooth and bone formation in a managed group of green iguanas (Iguana iguana, Linné 1758) kept for 1.5 years under experimentally controlled conditions and undergoing several dietary switches. We constrain rates of tooth elongation, which we observe to be slow when enamel is initially deposited (c. 9 µm/day), but then increases exponentially in the dentin root, reaching c. 55 µm/day or more after crown completion. We further constrain the total timing of tooth formation to ∼40-60 days, and observe highly variable timings of tooth resorption onset and replacement. Fluorescent labels clearly indicate cohorts of teeth recruited within Zahnreihen replacement waves, with faster sequential tooth recruitment and greater wave sizes posteriorly, where each wave initiates. Fluorescence further reveals enamel maturation after initial deposition. Rates of hard tissue formation in long bones range from 0.4 to 3.4 µm/day, correlating with animal weight gain and cortical bone recording the entire history of the experiment. We suggest additional labeling experiments to study hard tissue formation patterns in other reptiles, and propose strategies for chemical analyses of hard tissues in order to extract temporal information about past environments, behaviors, and diets from reptilian fossils throughout the Phanerozoic.

First report and molecular identification of a reptilian tick, Amblyomma helvolum (Acari: Ixodidae), infesting wild green iguanas, Iguana iguana (Reptilia: Iguanidae), in southern Taiwan.

The genetic identity of the reptilian tick, Amblyomma helvolum, infesting wild green iguanas (Iguana iguana) in Taiwan, was examined. Genetic identity was determined by analyzing the 16S mitochondrial DNA gene sequences obtained from 11 Taiwan A. helvolum compared with other Amblyomma species, with two Dermacentor species and two Rhipicephalus species serving as outgroups. Phylogenetic analysis revealed that all the Taiwan specimens were genetically affiliated with a monophyletic group of A. helvolum and can be discriminated from other Amblyomma species. Our results provide the first genetic identification of adult A. helvolum ticks infesting wild iguanas in Taiwan. Further studies focused on the seasonal prevalence and vectorial capacity of A. helvolum for various tick-borne pathogens will help to clarify the epidemiological significance of this species and its impact on animal and human health in Taiwan.

Limb bone strains during climbing in green iguanas (Iguana iguana): testing biomechanical release as a mechanism promoting morphological transitions in arboreal vertebrates.

Across vertebrate diversity, limb bone morphology is typically expected to reflect differences in the habitats and functional tasks that species utilize. Arboreal vertebrates are often recognized to have longer limbs than terrestrial relatives, a feature thought to help extend the reach of limbs across gaps between branches. Among terrestrial vertebrates, longer limbs can experience greater bending moments that might expose bones to a greater risk of failure. However, changes in habitat or behavior can impose changes in the forces that bones experience. If locomotion imposed lower loads in trees than on the ground, such a release from loading demands might have produced conditions under which potential constraints on the evolution of long limbs were removed, making it easier for them to evolve in arboreal species. We tested for such environmental differences in limb bone loading using the green iguana (Iguana iguana), a species that readily walks over ground and climbs trees. We implanted strain gauges on the humerus and femur, and then compared loads between treatments modeling substrate conditions of arboreal habitats. For hindlimbs, inclined substrate angles were most correlated with strain increases, whereas the forelimbs had a similar pattern but of lesser magnitude. Unlike some other habitat transitions, these results do not support biomechanical release as a mechanism likely to have facilitated limb elongation. Instead, limb bone adaptations in arboreal habitats were likely driven by selective pressures other than responses to skeletal loading.

Mycobacterium marinum Infection after Iguana Bite in Costa Rica.

Infections after reptile bites are uncommon, and microbial etiologies are not well defined. We describe a case of Mycobacterium marinum soft-tissue infection after an iguana bite in Costa Rica that was diagnosed through 16S rRNA sequencing and mycobacterial culture. This case informs providers of potential etiologies of infection after iguana bites.

Blood chemistry and biliverdin differ according to reproduction and tourism in a free-living lizard.

Changes in the physiological health of species are an essential indicator of changing conditions and environmental challenges. Reponses to environmental challenges can often induce stress, influence physiology, and change metabolism in organisms. Here we tested blood chemistry parameters indicative of stress and metabolic activity using an i-STAT point-of-care blood analyzer in seven populations of free-ranging rock iguanas exposed to varying levels of tourism and supplemental feeding. We found significant differences in blood chemistry (glucose, oxygen, carbon dioxide, hematocrit, hemoglobin, calcium, potassium, and biliverdin levels) among populations exposed to varying levels of tourism, and some variation between sexes and reproductive states. However, different variables are not directly related to one another, suggesting that the causal physiological pathways driving tourism-induced differences are influenced by mechanisms that are not detected by common analyses of blood chemistry. Future work should investigate upstream regulators of these factors affected by tourism. Regardless, these blood metrics are known to be both stress sensitive and related to metabolic activity, suggesting that exposure to tourism and associated supplemental feeding by tourists are generally driven by stress-related changes in blood chemistry, biliverdin, and metabolism.

Morphological and physiological traits of the respiratory system in Iguana iguana and other non-avian reptiles.

Functional morphology considers form and function to be intrinsically related. To understand organismal functions, a detailed knowledge of morphological and physiological traits is necessary. Regarding the respiratory system, the combined knowledge about pulmonary morphology and respiratory physiology is fundamental to understand how animals exchange gases and regulate critical functions to sustain metabolic activity. In the present study, the paucicameral lungs of Iguana iguana were analyzed morphometrically through stereological analysis using light and transmission electron images and compared with unicameral and multicameral lungs of six other non-avian reptiles. The morphological data were combined with physiological information to perform a principal component analysis (PCA) and phylogenetic tests of the relationship of the respiratory system. Iguana iguana, Lacerta viridis, and Salvator merianae presented similar pulmonary morphologies and physiologies when compared to Varanus examthematicus, Gekko gecko, Trachemys scripta, and Crocodylus niloticus. The former species showed an elevated respiratory surface area (%AR), a high diffusion capacity, a low volume of total parenchyma (VP), a low percentage of parenchyma concerning the lung volume (VL), and a higher surface/volume ratio of the parenchyma (SAR/VP), with high respiratory frequency (fR) and consequently total ventilation. The total parenchymal surface area (SA), effective parenchymal surface-to-volume ratio (SAR/VP), respiratory surface area (SAR), and anatomical diffusion factor (ADF) showed a phylogenetic signal, evidence that the morphological traits are more strongly correlated with the species' phylogeny than the physiological traits. In sum, our results indicated that the pulmonary morphology is intrinsically related to physiological traits of the respiratory system. Furthermore, phylogenetic signal tests also indicate that morphological traits are more likely to be evolutionary conserved than physiological traits, suggesting that evolutive physiological adaptations in the respiratory system could happen faster than morphological changes.