Microsatellites are useful markers to address questions of recent gene flow, given that they are relatively neutral to natural selection and show high levels of variability. To date, only one study has used these markers to answer ecological questions in the speciesrich lizard genus Liolaemus. Here, we use microsatellite loci to estimate population structure, paternity, and effective size of a population of L. xanthoviridis. The study took place in Isla Escondida Bay, Chubut (Argentina), during four spring-summer seasons (2012–2015). We marked and sexed 227 captured individuals and transported 10 gravid females to our laboratory. Digits of marked lizards were used for molecular work, and we resolved eight microsatellite loci to characterize genetic diversity, paternity, and population structure. We found no evidence of multiple paternity, and our samples constitute a single genetic population of L. xanthoviridis. Our results show that genetic diversity is higher in L. xanthoviridis than in many other species of lizards we found in the literature. Such high genetic diversity is important given the restricted geographic distribution of this species.

The mechanism behind the female-biased sexual size dimorphism in snakes (SSD) is usually linked to a delay in females' maturation and/or higher growth rates during their immature phase. Studies on growth rates of immature snakes have been focused on sex differences related to feeding rates instead of food conversion rates. We tested the hypothesis that growth rates of immature female lanceheads are higher than that of immature males and determined if this difference is related to differential food conversion rates between genders. During 18 months, we collected data on growth rates in juveniles from a litter of a species (Bothrops fonsecai) with a female-biased sexual size dimorphism under a controlled feeding regime. Our results showed that females, even receiving the same amount of food than males, presented higher growth rates in all parameters measured (snout-vent length, mass, stoutness, snout-vent length-specific growth rate and mass-specific growth rate). Our data support a mechanism of establishment of sexual size dimorphism in a female-biased species apart from feeding rates but linked to a different feeding conversion between sexes. Based on our results, we also suggest that these differences in feeding conversion must be linked to sexual differences in energy assimilation efficiency.

The teiid genera Dicrodon and Teius possess transverse bicuspid posterior teeth on the dentaries and maxillae. In general, their dentition is considered to be comparable, and little attention has been given to their dental morphology. Here the dentition of Dicrodon is described in detail and compared to that of Teius. The dentition of Dicrodon differs from that of Teius in the following characters: both cusps are more concentrically placed (in occlusal view); the lingual cusp is developed on a crescent ridge; the crescent ridge may present mesial and distal protuberances; the lingual cusp is shorter (never as tall) as the labial cusp; and the intercuspid ridge is incomplete (missing in the lingual cusp). These characters allow the dental diagnosis of both genera.

Amphibians exhibit a great diversity of reproductive modes. Nevertheless, reproductive biology is still unknown for several threatened Neotropical species, including the Critically Endangered microendemic Valcheta frog, Pleurodema somuncurense. This paper looks at the reproductive biology of this species, describes its behavior, amplexus, spawning, clutches, embryonic development and breeding microhabitats, and discusses differences and similarities between it and the other Patagonian species included in the P. thaul clade: P. bufoninum and P. thaul. Fieldwork was conducted from 2013–2015 in the headwaters of Valcheta Stream (northern Patagonia, Argentina), over the whole known range of P. somuncurense. We also added information from an ex situ survival colony of this species. Pleurodema somuncurense has prolonged seasonal reproductive activity during spring-summer and presents features of both explosive and prolonged breeders. The Patagonian species of the P. thaul clade all have inguinal amplexus and lay pigmented eggs in gelatinous strings. During inguinal amplexus, the male P. somuncurense arches its body, bringing its vent closer to the female's, while contracting its body muscles rhythmically and moving its pelvic girdle up and down while the female spawns the eggs. We occasionally recorded mating calls, release calls, and warning vibrations. Although there are similarities among the three species, P. somuncurense has some specific features, such as scramble competition, which has not yet been recorded for any other species in the genus, and the mating call, although better records in natural conditions are needed for detailed analysis and more robust comparison. Because the breeding microhabitats used by P. somuncurense are currently under disturbance from livestock, their protection should be a matter of concern.

Tadpoles of some anuran species are known to survive out of water, but information is scarce or nonexistent for most species. We experimentally tested the survival ability of Amazonian tadpoles of six species out of water in conditions that simulated pond drying. Specifically, we tested the hypothesis that tadpoles typical of habitats subject to fast drying would have higher capacity to survive without free water. We found higher survival rates for some species that usually occur in temporary ponds and the lowest one for a species from perennial ponds. However, we also found species from temporary ponds and streams with intermediate tolerance to desiccation. Tadpole survival differed among species and increased in function of body mass but was not related to the probability of each species being subject to periods without water in their habitats. Therefore, we reject the hypothesis that tadpole survival in the absence of water is a simple function of the probability of ponds drying.

Hematological parameters values for normal animals can reflect the health status of the individual and population, as well as the fitness of the species. Here, we determined the hematological parameters of wild caught Batrachuperus yenyuanensis. Blood samples were collected from 55 individuals B. yenyuanensis from a wild populations of West China and analyzed. Although the values of erythrocyte morphometric characters and hematological parameters varied between males and females, the difference was only significant in the case of the neutrophil count, with more neutrophils in females. The mean erythrocyte count was 7.20 × 10⁴/mm³ (3.00 × 10⁴–12.00 × 10⁴/mm³), mean leukocyte count was 3.10 × 10³/mm³ (0.58 × 103–7.75 × 10³/mm³), mean hematocrit (Hct) was 30.49% (15.60–46.00%), mean cell volume (MCV) was 4.57 × 10³ fl (2.21 × 103–8.57 × 10³ fl), mean cell hemoglobin (MCH) was 0.75 × 10³ pg (0.33 × 10³–1.04 × 10³ pg), mean cell hemoglobin concentration (MCHC) was 16.61% (8.50–25.32%) and mean hemoglobin was 5.00 g/dl (1.5–7.5 g/dl). This is the first report on hematological parameters of B. yenyuanensis, and the results may serve as a reference for health assessment and future study of this species. Comparison of our results to those of other hynobiid salamanders indicated that hematological parameters have species-specific and genus-specific characteristics.

Species that present a disjunct distribution pose the question of how much the isolated populations differentiated from each other. The teiid lizard Kentropyx striata is an inhabitant of áreas of savanna in northern South América, including several savanna enclaves within Amazônia. The population from Sipaliwini savanna, at the southern border of Suriname, was proposed to represent a distinct subspecies (Kentropyx striata viridicervix), but this proposition was not widely accepted due to the extensive variation observed outside Suriname and the necessity of an analysis of geographic variation in the whole group, which had not been done. Here, we performed a Discriminant Function Analysis of the morphological traits of five geographically isolated groups of K. striata from Brazil and Suriname, compared snout-vent length and hemipenis separately, and performed a Procrustes Analysis to evaluate the degree to which geographic distance could explain the differences. Even though each of these groups clustered in the multivariate space, none was completely isolated from others, with recognition between groups ranging from 50-81%. Hemipenes were similar in all groups and correlation between morphological and geographic distance was low (t₀ = 0.37). We conclude that there is no basis for subspecies or additional species recognition within Kentropyx striata and suggest that these groups became isolated in relatively recent times, similarly to what has been recovered for other inhabitants of Amazônian savannas.

Ameerega hahneli is a terrestrial dendrobatid frog widely distributed in the Amazon region. The tadpole of this species was formally described based on eight specimens in the early developmental stage 25, when some of the morphological structures were still not fully developed. In this study, the tadpoles of A. hahneli are redescribed based on 78 individuals in 14 different developmental stages. Additionally, we provide data on the ontogenetic variations and development sites of tadpoles. Specimens were collected in streamside ponds and streams of non-flooded forest during the rainy season. The tadpole of A. hahneli at stage 36 is characterized by: body elongate, depressed (lateral view), and oval (dorsal view); small size (mean 23.96 mm, range 21.7-26.2 mm); oral disc anteroventral; labial tooth row formulae 1/2; marginal papillae uniseriate, triangular, and distributed only on the lower labium. Like other tadpoles of the genus, the upper jaw sheath is W-shaped with a ventral notch and the lower jaw sheath is V-shaped, the spiracle is sinistral, and the vent tube is dextral. Ontogenetic variations were observed in body size, number of marginal papillae, lateral line system and ventral coloration. Total length increased gradually from the stage 25 (14.67 mm) to stage 37 (26.70 mm), the latter being the maximum total length observed. The combination of the morphological organization of its labial tooth row formulae and the presence of triangular marginal papillae only at the posterior labium allows the A. hahneli tadpoles to be easily distinguished from all the others species of the genus Ameerega.