We describe the advertisement call of Pristimantis zophus, a small and endemic Colombian rainfrog distributed throughout the cloud forests of the northern region of Western Andes. We analyzed 163 advertisement calls from six males. The advertisement call of P. zophus is relatively simple, short, with a duration of 0.227 ± 0.126 s (0.090–0.415), and consists of one or two notes of a single pulse and dominant frequency of 2.97 ± 0.100 (2.72–3.21 kHz). In addition, we briefly discuss aspects of the variation of the advertisement call and report some observations of the natural history of this species.

We describe a new species of Leptophis from the Caatinga ecoregion encompassing the semi-arid region of Brazil. Phylogenetic analysis of 16S rDNA sequences indicate that the new species is nested deep within the L. ahaetulla complex. The new species differs from all other congeners in the following unique character combination: two dorsolateral Light Emerald Green (142) to Robin's Egg Blue (161) stripes separated from each other by Pale Buff (1) to Smoke Gray (266) vertebral stripe (continuous to tail) present; loreal scale absent; maxillary teeth 21–24; ventrals 158–177; subcaudals 137–162; black spots on head absent; supracephalic plates of head not edged with black pigment; adult color pattern lacking dark oblique bands; keels absent on first dorsal scale rows; hemipenis unilobed, capitate, with undivided sulcus spermaticus. The new species is distinguished from L. ahaetulla ahaetulla by the Light Emerald Green (142) to Robin's Egg Blue (161) (in life) dorsolateral stripes separated from each other by a Pale Buff (1) to Smoke Gray (266) vertebral stripe (at least anteriorly), and by having white to Pale Sulphur Yellow (92) scales on the first (on anterior region of body) to fourth (midbody region) scale rows [vs. Light Grass Green (109) to Light Emerald Green (142) with Yellow Ocher (14), Cinnamon-Drab (50) or Sulphur Yellow (80) vertebral stripe; second to third—occasionally the fourth—scale rows Sulphur Yellow (80), at least anteriorly], wider snout (vs. narrow), postocular stripe wider (vs. narrow), basal region of hemipenis with 10–14 spines and first row of hemipenial body with 8–9 spines (vs. 18–22 in the basal region and 5–8 in the first row). The new species differs from L. a. liocercus, which is also distributed in the Northeast Region Brazil with a small overlap in distribution, by the dorsolateral stripes (vs. dorsum unstriped), and 18–22 spines in the fourth row of the hemipenial body (vs. 11–18). Recognition of the new species is also consistent with uncorrected pairwise distances between 16S rDNA sequences.

Night count surveys are one of the most used methods to study distribution and population parameters in crocodilians. However, there are some methodological constraints that prevent the visualization of animals submerged or hidden behind vegetation. We studied the proportion of caimans that were detectable to observers during night count surveys based on the monitoring of seven adult Caiman latirostris females with radio transmitters (VHF, GPS, and UHF). Fieldwork was carried out in a protected area with a natural stream and a lagoon (30°11′26″S, 61°00′27″W) between 12 January and 29 April 2011 in Santa Fe, Argentina. Only locations acquired at night (18:00–05:00) were considered for analysis, and those acquired within vegetation were considered potentially undetectable. As the lagoon is mostly covered with vegetation (e.g., cattail), most of the animals were not visible to observers (62.5–100%, average > 80%). In contrast, virtually all individuals (100%) were potentially visible in the stream. The use of data collected in telemetry studies can be useful to estimate detectability of cryptic species such as the broad-snouted caiman. An understanding of animal detectability is necessary, as counts of individuals is often used in decision-making for crocodilian conservation, sustainable use, and control.

Although caiman populations are being conserved in some protected areas, they face threats related to human pressure, which may ultimately influence their distribution, abundance, and behavior. In this study, we investigated the population ecology (encounter rate, size structure, sex ratio, and injury frequency) and the effects of human disturbance on Melanosuchus niger and Caiman crocodilus populations in Cantão State Park, southern Brazilian Amazon, Central Brazil. We assessed human pressure on both populations, testing the human disturbance–abundance and human disturbance–size structure relationships. We sampled waterbodies within (lakes) and adjacent to (river) protected areas via nocturnal surveys and captures. Human pressure in the river was assessed and categorized via transects with low, medium, and high levels of disturbance. Our results indicate that C. crocodilus was more abundant than M. niger, with populations of both species mainly composed of juvenile males. We also observed that injuries were more prevalent in juveniles and males. Human disturbance negatively affected C. crocodilus abundance, but no effect was found for M. niger. We found no significant effect of human disturbance on size structure for either species; however, the response for each species differed. Snout–vent length (SVL) decreased with increasing human pressure level in the C. crocodilus population, whereas M. niger showed a greater SVL at higher human pressure levels. Our results suggest that human disturbance related to boat traffic, pollution, riverine population, land use, and human activities negatively influence crocodilian populations in their distribution through a distance–abundance relationship. Additionally, the proximity of settlements and accessibility to protected areas are factors related to human disturbance and should be considered in government decisions and the management of protected areas by environmental agencies. Our results improve our understanding caiman population responses to human disturbance.

Crocodilians in aquacultural settings exhibit variations in growth and condition. The underlying cause of this has yet to be elucidated, but corticosterone (CORT, the main crocodilian stress hormone) is thought to play a role in this. In this study, we measured baseline plasma CORT, heterophil-lymphocyte (H/L) ratios, relative glucocorticoid receptor (GR) levels in the forebrain, and body condition index (BCI) of juvenile American alligators (Alligator mississippiensis). Both univariate and multivariate analyses were used to investigate underlying relationships. In univariate analysis, BCI was negatively related with GR levels, but not by plasma CORT. Multivariate analysis revealed that both relative forebrain GR levels and plasma CORT were negatively related with alligator BCI: alligators with higher body condition had lower levels of CORT and GRs. However, H/L ratios were unrelated to BCI. Our results implicate dysregulation of the hypothalamic-pituitary-adrenal axis as an important factor influencing crocodilian body condition.

Efferent ductules are part of the male reproductive system. They play a role in providing a nutrient environment for the maintenance of the spermatozoa. Efferent ductules are studied exhaustively in birds and mammals, but reptiles, the first vertebrates that successfully adapted to life on land, have received little attention among the comparative biologists. Hence, the present study aimed to study the seasonal variation in an extra-testicular portion, the efferent ductules, in the male reproductive system of the lizard Eutropis carinata. The results revealed that the epithelium of these ductules is lined by cuboidal non-ciliated cells and ciliated cells. Ultrastructural features of the non-ciliated cells revealed the role of endocytosis and secretion. During the breeding season, the epithelium is positive to periodic Schiff and bromophenol blue staining, indicating the presence of carbohydrate and protein. Histological and histometric parameters exhibit significant seasonal differences. However, there is not much seasonal ultrastructural variation, except for reduced cell height and less cytoplasm as well as reduced granular material in the lumen. Based on the above results, the present study for the first time reveals that the efferent ductules form an essential link between the testis and the epididymis and serve as a conduit for sperm, absorption of rete testis fluid, and secretion. Further, although there is no seasonal variation in the type of cells throughout the length of the efferent ductules during the breeding and non-breeding seasons in E. carinata, the morphology, ultrastructural modifications, activity, and function vary during these seasons.

Phagocytosis is a primary and highly conserved mechanism for clearing the extracellular milieu from pathogens and debris. In amphibians, the lack of antibodies for characterizing the different phenotypes of phagocytic cells has impaired the study of the phagocytic process. We used conventional and flowsight cytometry to determine immune cells' phagocytic activity from the blood and peritoneum of toads by in vitro and in vivo assays. Macrophage-like and neutrophil-like cells were clustered and analyzed according to cell morphology and the number of internalized zymosan particles by flowsight cytometry. We identified peritoneal and blood phagocytes (macrophage-like/monocyte-like and neutrophil-like) and lymphocyte-like cells. Besides, we observed monocyte-like/macrophage-like and neutrophil-like cells engulfing up to seven zymosan particles. Assessing the phagocytic activity from blood and peritoneal phagocytes using in vitro and in vivo assays brings better insights into phagocytosis in amphibian immune cells from distinct body compartments and approaches. Moreover, it is worth highlighting the importance of morphologically identifying the cells and evaluating the number of internalized particles by flowsight cytometry, a valuable asset to further explore phagocytosis and other cellular processes in amphibians under field and laboratory conditions.

Changes in the body temperature (T_b) of reproductive females are well documented in squamate reptiles. However, the direction of these changes varies among species. Pregnant females may exhibit a lower or higher (and less variable) T_b than nonpregnant females. In some species, pregnancy has no detectable effect on female T_b. In this study, we compared the T_b of female rattlesnakes (Crotalus durissus) in different reproductive statuses (pregnant and nonpregnant) to investigate whether pregnancy influences T_b. We measured the T_b of female rattlesnakes kept in a semi-natural outdoor enclosure during summer and spring 2016 and summer 2017. Pregnant females selected a higher mean T_b than nonpregnant females. Moreover, we found significant differences in T_b among seasons. Body temperatures in summer 2017 were higher than in other seasons; however, reproductive status did not influence T_b variance. Therefore, our results agree with the hypothesis that females change their thermoregulatory behavior during pregnancy. Female rattlesnakes may increase their T_b during pregnancy to increase offspring fitness or to maximize their lifetime fitness.