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The mineralized dermal layer (MDL) is found in most terrestrial anurans. Its thickness represents on average up to 8% of that of the entire skin. It has been proposed that it may reduce body water loss, act on homeostasis, support skin structure, or conversely, it may be a currently functionless trait constrained by groups' evolutionary history. We described the MDL morphology of 11 Brachycephalus species, terrestrial, miniaturized and microendemic anurans, and tested for its relationship with climate of higher latitude regions of the Atlantic Rainforest of Brazil. All species presented MDL, described with two distinct morphological patterns: homogeneous or heterogeneous MDL, the latter distinguishable by MDL with dorsal or lateral expansion, sometimes up to the limit of the epidermis and comprising up to 50% of the thicknesses of the entire skin. Climate differed between locations by MDL morphological group, less rainy or seasonally less rainy where species with heterogeneous MDL occur. Our results indicate that the abundance of calcium in MDL and its heterogeneous condition suggest its adaptive function in reduce water loss. Such adaptations in anurans in very humid highlands reinforce the mountains' propensity for rapid loss of humidity, demystifying them as an extremely abundant source of water. This is the third study that tested the relationship between the MDL morphology and the environment where species occur and the first that correlated this structure with the climate of anurans of the same habit and distributed in a single habitat, the Atlantic Rainforest. [ABSTRACT FROM AUTHOR]

Abstract: The small geographical range of highly endemic species is an important factor to be considered in conservation initiatives because it can increase their risk of extinction, as well decrease their probability of discovery. In this study, we use environmental niche modeling (ENM) to investigate the distribution of Brachycephalus, an anuran genus characterized by microendemic species living mostly in montane habitats along the Brazilian Atlantic Rainforest. Given that traditional ENM is not possible in the case of Brachycephalus because most of its species have limited geographical ranges, we analyzed an ensemble dataset that combined records of most described species, as well as new species that are currently being described, while accounting for heterogeneity in their climatic niches. Niche heterogeneity was quantified by ordination of the bioclimatic variables associated with their occurrence records, followed by unguided clustering of the resulting ordination scores. Out of an initial dataset of 544 records, careful curation reduced it to 75 records of 24 species and 71 localities. Interestingly, the three major clusters of climatic niches found in Brachycephalus corresponded largely to the three previously recognized phylogenetic lineages in the genus. The pernix cluster included the highly endemic species from southern Brazil that were most restricted to high-elevation areas, whereas the didactylus cluster encompassed species with broader geographical ranges that extended into lowland regions of the Atlantic Rainforest. Finally, the ephippium cluster included species from southeastern Brazil with intermediate levels of endemism. The detection of several isolated locations with potentially suitable habitats indicate that the diversity of Brachycephalus could still be considerably underestimated. [Copyright &y& Elsevier]

A new species of miniaturized froglet (genus Brachycephalus) is described from Morro Prumirim in the municipality of Ubatuba, São Paulo, southeastern Brazil. Specimens were collected from the leaf litter at approximately 800 m above sea level. The new species is distinguished from all its congeners by the combination of the following characters: snout–vent length 8.7–13.4 mm; skin on head and dorsum with dermal ossification; general color orange, with a narrow brownish vertebral stripe and belly without spots; and skull, spinal processes of sacral and pre-sacral vertebrae, and process of the fourth vertebra hyperossified. Canonical variates analysis of linear body measurement demonstrates that the new species is easily discriminated from other Brachycephalus species with which it shares an intermediate condition of hyperossification. [ABSTRACT FROM AUTHOR]

Abstract: Toadlets of the genus Brachycephalus are endemic to the Atlantic rainforests of southeastern and southern Brazil. The 14 species currently described have snout–vent lengths less than 18mm and are thought to have evolved through miniaturization: an evolutionary process leading to an extremely small adult body size. Here, we present the first comprehensive phylogenetic analysis for Brachycephalus, using a multilocus approach based on two nuclear (Rag-1 and Tyr) and three mitochondrial (Cyt b, 12S, and 16S rRNA) gene regions. Phylogenetic relationships were inferred using a partitioned Bayesian analysis of concatenated sequences and the hierarchical Bayesian method (BEST) that estimates species trees based on the multispecies coalescent model. Individual gene trees showed conflict and also varied in resolution. With the exception of the mitochondrial gene tree, no gene tree was completely resolved. The concatenated gene tree was completely resolved and is identical in topology and degree of statistical support to the individual mtDNA gene tree. On the other hand, the BEST species tree showed reduced significant node support relative to the concatenate tree and recovered a basal trichotomy, although some bipartitions were significantly supported at the tips of the species tree. Comparison of the log likelihoods for the concatenated and BEST trees suggests that the method implemented in BEST explains the multilocus data for Brachycephalus better than the Bayesian analysis of concatenated data. Landmark-based geometric morphometrics revealed marked variation in cranial shape between the species of Brachycephalus. In addition, a statistically significant association was demonstrated between variation in cranial shape and genetic distances estimated from the mtDNA and nuclear loci. Notably, B. ephippium and B. garbeana that are predicted to be sister-species in the individual and concatenated gene trees and the BEST species tree share an evolutionary novelty, the hyperossified dorsal plate. [Copyright &y& Elsevier]

Two new species of brachycephalid frogs are described from Pico Marumbi, municipality of Morretes, and Pico da Igreja, municipality of Guaratuba, Paraná State, southern Brazil. The new species share the following attributes: body bufoniform; skin on top of the head, and central part of the back body smooth with no dermal co-ossification; outer metatarsal tubercle distinct; dermal roofing bones of skull unornamented; all paired cranial bones distinct and not fused; quadratojugals, and maxillary odontoids present. The new species from Pico Marumbi is characterized by male SVL = 11.6-12.5 and female SVL = 1.3.0-1.4.5 ram; and general color orange with dorsal reddish-brown irregular markings, lateral surfaces with small dark brown spots, and belly with brownish spots and small dots. The new species from Pico da Igreja is characterized by male SVL = 1.2.6-13.9 and female SVL = 14.6-15.3 ram; and general color orange, lateral surfaces with small dark brown spots, and belly with brownish coalescent spots and small dots. Comparisons with other brachycephalid species mad osteological data are provided. [ABSTRACT FROM AUTHOR]

Anthropogenic forces are increasing climate anomalies and disease pressure in tropical forests. Terrestrial-breeding amphibians, a diverse group of highly endemic tropical frogs, have been experiencing cryptic population declines and extinctions, most of which have been retrospectively linked to climate anomalies and the fungal pathogen Batrachochytrium dendrobatidis (Bd). However, the spatiotemporal drivers of Bd infection in these species are unresolved. We tracked microhabitat conditions and Bd dynamics in terrestrial-breeding frogs in Brazil's Atlantic Forest over an annual cycle that coincided with a period of low rainfall compared to historical averages. An increase in Bd prevalence during the warm/wet season was attributable to pathogen spillover from co-occurring aquatic-breeding frogs. The deficit in rainfall compared to historical trends was the best predictor of spikes in Bd infection loads one month later and mortality among heavily infected frogs two months later. We suggest that hydrological stress may intensify seasonal pathogen amplification in direct-developing frogs, to an extent that may trigger localized disease clusters or potentially shift disease dynamics from enzootic to epizootic, even in areas with a relatively long history of host-pathogen coexistence. • Tropical terrestrial-breeding frogs are declining from the disease chytridiomycosis. • We tracked spatiotemporal drivers of infection in Brazilian terrestrial frogs. • Drought was the best predictor of increased host infection loads and mortality. • Our study includes the first real-time report of chytridiomycosis in the wild in Brazil. • Increasing drought stress under global change may amplify frog disease risk. [ABSTRACT FROM AUTHOR]

The advent of next-generation sequencing allows researchers to use large-scale datasets for species delimitation analyses, yet one can envision an inflection point where the added accuracy of including more loci does not offset the increased computational burden. One alternative to including all loci could be to prioritize the analysis of loci for which there is an expectation of high informativeness. Here, we explore the issue of species delimitation and locus selection with montane species from two anuran genera that have been isolated in sky islands across the southern Brazilian Atlantic Forest: Melanophryniscus (Bufonidae) and Brachycephalus (Brachycephalidae). To delimit species, we obtained genetic data using target enrichment of ultraconserved elements from 32 populations (13 for Melanophryniscus and 19 for Brachycephalus), and we were able to create datasets that included over 800 loci with no missing data. We ranked loci according to their number of parsimony-informative sites, and we performed species delimitation analyses using BPP with the most informative 10, 20, 40, 80, 160, 320, and 640 loci. We identified three types of phylogenetic node: nodes with either consistently high or low support regardless of the number of loci or their informativeness and nodes that were initially poorly supported where support became stronger as we included more data. When viewed across all sensitivity analyses, our results suggest that the current species richness in both genera is likely underestimated. In addition, our results show the effects of different sampling strategies on species delimitation using phylogenomic datasets., (Copyright © 2019 Elsevier Inc. All rights reserved.)