Amphibian activity is affected by environmental variables, and in some species from tropical and subtropical regions the males in activity are bigger at the beginning of the rainy season than at the end. In this context, the relationship between male calling activity and climatic variables was evaluated in a population of Boana pulchella from Uruguay. This tree frog is distributed from southern Brazil to central and northern Argentina and is a prolonged breeder, enabling us to evaluate temporal male body size variations. The study population was in a temperate region with seasonal variation of temperature and aseasonal rainfall. Monthly mean temperatures and total rainfall were obtained from a meteorological station 15 km from the semi-permanent pond where the sampling work was conducted. From November 2005 to November 2006, 10 m from this pond, and three days per month, air temperature and relative humidity were recorded, and monthly photoperiods were calculated. From 20:00–22:00 on the days climatic variables were determined, the activity of B. pulchella was measured through an acoustic and visual encounter survey. In addition, animals were collected, measured, and released. Male activity was not correlated with either mean temperature or photoperiod. This was compatible with the aseasonal male activity calculated with circular statistics. However, male activity was positively correlated with rainfall. The occurrence of froglets was seasonal, concentrated mainly in November 2005. The males in the cold season were larger than those in the warm season. Qualitative comparison among calling phonologies at different latitudes indicated B. pulchella was inactive during some cold months in the south and during some warm months in the north. This geographical variation in calling phenology indicates that local environmental temperatures affect activity and likely reproduction of B. pulchella, with the optimum being in the range of cold to mild.

The Tzabcan rattlesnake (Crotalus tzabcan) is endemic to the Yucatán Peninsula and is part of the C. durissus complex. Although relatively widespread, it is rather an uncommon species; therefore, little is known about its natural history. Herein, we describe the diet of C. tzabcan on the basis of data from field encounters, museum specimens, and published data. Dietary samples were collected from Campeche, Quintana Roo, and Yucatán, Mexico, and literature records from Belize, representing most of the species' distribution range. Examination of 50 individuals resulted in 28 prey items obtained from 27 snakes. The diet of C. tzabcan consisted exclusively of mammals, including the orders Rodentia (86% of the prey items) and Soricomorpha (7%), and no ontogenetic shift in prey type was detected. However, an ontogenetic telescope is evident, where adults consume larger prey than juveniles but continue feeding on small prey. No sexual dimorphism in snout–vent length and total length was detected in C. tzabcan. No sexual differences in prey mass were found when controlling for snake body length, nor when comparing between sexes in adults and juveniles. The presence of prey was not related to snake collection date, suggesting year-round feeding. There was no difference in prey class and size among snakes from Yucatán dry forest and moist forest. These results suggest a homogenous diet among sexes, seasons, and populations. This is the first detailed study on the diet and feeding ecology of C. tzabcan, and it adds five new prey species: Cryptotys mayensis, Heteromys desmarestianus, H. gaumeri, Oryzomys couesi, and Rattus rattus, as well as two previously reported ones: Mus musculus and Sigmodon toltecus. These findings contrast with anecdotal reports of C. tzabcan consuming reptiles and birds and show many similarities with the related species C. durissus. Additional studies on the natural history of C. tzabcan and related species would help to better understand how the feeding ecology of Neotropical rattlesnakes differs from those species of temperate zones.

Rhachisaurus brachylepis is a poorly known lizard species that was described from Serra do Cipó in the southern portion of the Serra do Espinhaço (Espinhaço Mountain Range), Minas Gerais, Brazil. Almost 50 years after its original description, the species remains known from only a few specimens and brief comments in the literature. Here, we present new data on morphological variation (meristics, morphometrics, and color pattern) within the species on the basis of the reexamination of old specimens housed in herpetological collections and recently collected material. We also provide an emended diagnosis, as well as diagnostic characters relative to other genera of Brazilian gymnophthalmids. We provide additional information on the species' geographical distribution and an updated distribution map, extending its range and filling in some gaps. We also establish the precise placement of the type locality. The new records of R. brachylepis indicate that the size of its geographical distribution is greater than previously thought. Further, we discuss the controversial record of the species from northern Brazil.

Here, we present data on reproductive biology and sexual dimorphism of a species of Gymnophthalmus (G. vanzoi). We conducted the study in an urban area in the municipality of Santarém, on the campus of the Universidade Federal do Oeste do Pará, Pará state, Brazil. We collected data from 61 males, 79 females, and 9 individuals of unknown sex. Adults were sampled throughout the year, and juveniles were sampled for nine months. Adult females were larger and heavier than males. We observed sexual dimorphism in snout–vent length, length between limbs, head length, head width, head height, hind limb length, tail width, body mass, and coloration. We recorded reproductive females during 6 months, with the largest secondary follicles observed in June and August, the period of lowest precipitation. Reproductive males were recorded throughout the year, occurring at higher frequencies in December, January, and June–November. Testicular volume did not differ significantly among months (P = 0.0884). We collected the smallest individuals in January, March, July, August, November, and December, which suggests that recruitment occurs throughout the year. Despite the evidence of seasonality in the reproductive cycle with larger follicles and larger volume of testes in the drier season, we suggest that reproduction in G. vanzoi is continuous throughout the year, as we did not find statistical differences in the size of testicles (adjusted for subject body size) among months, and because recruitment occurs across various months of the year.

Population parameters can be estimated on the basis of capture-mark-recapture (CMR) studies, which require accurate and continuous identification of studied individuals. Amphibians that cannot be identified by unique color patterns represent a problem for these types of studies due to variable interspecies suitability of different marking methods. One alternative to the traditional but questionable toe-clipping method is visible implant elastomer (VIE) tagging. VIE has been used successfully, mainly for tagging different species of terrestrial salamanders, but it has not been evaluated systematically for biphasic newts. In this study, the efficiency of VIE tagging was tested on smooth newts (Lissotriton vulgaris), with controls for body length, sex, position of tag, color of tag, and personal experience with tagging. Two tags, originally injected into each individual, were visible only in 39.5% of the newts after 49 days. Most of the tags that failed (72.4%) were lost completely. Retention rates for the VIE tags were lowest for younger tags but improved over time. Tags were lost more from the front than from the hind legs (42.1% vs. 34.2%), the person more experienced in marking had fewer tag losses (22.8% vs. 51.2%), and males lost more tags from their hind legs than females (52.8% vs. 17.5%). This study shows that VIE marking is not a conclusively reliable method for CMR studies of small salamanders during the breeding (water) period. The future of individual recognition, for the purpose of CMR studies, lies probably in non-invasive, computer-assisted photo identification methods.

We describe for the first time the tadpole of two endemic harlequin frogs of the Sierra Nevada de Santa Marta, north of Colombia: Atelopus nahumae and A. laetissimus. In addition, we provide further morphological data for a third species, A. carrikeri. We also discuss some external morphological features for the tadpoles of these species and compare them with data currently available in the literature for the genus and with other larvae deposited in the amphibian collection of the Instituto de Ciencias Naturales of the National University of Colombia. The examined characters comprise eight morphometric variables and many traits of external morphology related with the oral apparatus, abdominal disc, fins, and dorsal color pattern. The tadpoles of A. nahumae and A. laetissimus are gastromyzophorous and morphologically similar, sharing a great number of features with their congeners. The tadpoles of A. nahumae, A. laetissimus, and A. carrikeri contrast morphometrically; total length and tail width are the morphometric traits that are useful to differentiate among them. They are also differentiated by the size of the abdominal sucker and spiracle. In A. carrikeri, the abdominal sucker is large relative to that of A. nahumae and A. laetissimus; the spiracle of A. laetissimus and A. carrikeri is not visible in ventral and dorsal view, whereas it is large and conspicuous in A. nahumae. The tadpoles of the species from Sierra Nevada de Santa Marta differ from most of their congeners found in the Cordillera Oriental and Central of Colombia by lacking a dark band on the fins and caudal musculature. We recorded abiotic factors of the microhabitat where tadpoles of A. nahumae were observed (temperature, dissolved oxygen, and water depth). Our results indicate that the probability of finding A. nahumae tadpoles depends on the depth of the stream.

Research on elusive amphibians is challenging, resulting in a lack of basic information on their natural history. This is the case of Leptodactylus nesiotus, a rare and elusive frog found in a small swamp in the southwestern peninsula of the island of Trinidad (West Indies). Here, we provide additional call descriptions for data collected in the field (Trinidad) and laboratory in 2004, including descriptions of both advertisement and aggressive calls. The notes in the advertisement calls were divided in two types of pulses, both lasting on average less than 0.04 s and with average peak frequencies less than 16,000 Hz. The aggressive calls also displayed two types of pulses lasting 0.06 s maximum on average and with highest average peak frequency of 1,612 Hz. The only significant difference between these two call types relates to the temporal structures, but a larger dataset is needed to confirm the pattern. There were no temporal significant differences between the calls described here and the ones described in earlier literature, although we provide a more detailed call description.

Sexual dimorphism is a widespread phenomenon throughout the animal kingdom and has attracted considerable interest in evolutionary biology. Studies on sexual dimorphism in hynobiid salamanders, which exhibit external fertilization and have two different habitat preferences, are limited. In this study, we analyzed sexual size and shape dimorphism of the stream-dwelling salamander Batrachuperus pinchonii based on deposited specimens, which were collected from the same locality with the same sampling date, and then explored if either habitat influences sexual dimorphism. Our results revealed no sexual dimorphism in body size (expressed by snout–vent length); however, other morphometric data indicated a female-biased dimorphism in head length, head width, distance of extremities, chest width, and a male-biased dimorphism in foreleg length, foreleg width, fore palm width, hindleg width, and hind palm width. These results would give some merit for future ecological and functional studies on reproduction in B. pinchonii. That is, female-biased head shape is likely related to ecological selection (e.g., reduction of intersexual food competition) and reproductive investment (e.g., intake of more energy). A female-biased trunk dimorphism may contribute to a fecundity advantage (e.g., increase in reproductive output). Male-biased limb dimorphism may relate to reproduction success. We failed to find dimorphic characteristics related to habitats.

The Rhinella granulosa group currently comprises 14 species of Neotropical toads, and its monophyly is strongly supported by several synapomorphies, including a distinctive set of larval characters. Recently, the identities of specimens used in the description of the tadpoles of R. major and R. mirandaribeiroi were questioned. In this work, we revise the larval external morphology of these species based on properly identified tadpoles and examine for the first time the tadpoles of R. bernardoi. Tadpoles of R. major have the labial tooth row formula 2/2 and a striped tail pattern, which were recovered as synapomorphies of the group. In contrast, tadpoles of R. mirandaribeiroi show a third posterior labial ridge arranged on a medial flap, a condition suggested as a synapomorphy of a derived subclade of the R. granulosa group. Lastly, tadpoles of R. bernardoi differ from the remaining tadpoles within the group by lacking the typical striped tail muscle pigmentation.

Rhinella yunga is a poorly studied but locally abundant endemic bufonid toad found only in two habitat islands of the buffer zones surrounding the Yanachaga-Chemillén National Park and the Pui Pui Protected Forest in the Selva Central, Peru. Rhinella yunga is unique because it lacks a complete tympanic ear and is larger than most toads lacking a tympanic ear. Here, we report on the natural history, reproductive behavior, and territorial and release calls of R. yunga following field- and captivity-based observations across two breeding seasons. We also provide a description of tadpole external morphology based on a developmental series of laboratory-reared larvae. We found that R. yunga (1) uses low frequency calls (800–1,100 Hz) that are likely detectable without tympanic middle ears and (2) appears to exhibit an unusual mating system with female competition at breeding ponds prior to male arrival. Under these conditions, the need to hear male advertisement calls might have become unnecessary in this species.