Widespread occurrence of the amphibian chytrid panzootic lineage in Uruguay is constrained by climate.

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causes chytridiomycosis, a disease among the main causes of amphibian declines worldwide. However, Bd studies on Neotropical amphibians from temperate areas are scarce. We present a comprehensive survey of Bd in Uruguay, in temperate central eastern South America, carried out between 2006 and 2014. Skin swabs of 535 specimens of 21 native and exotic frogs were tested by PCR. We used individual-level data to examine the relationship between infection, climatic variables, and their effects on body condition and the number of prey items found in stomach contents. Infection was widespread in free-ranging anurans with an overall prevalence of 41.9%, detected in 15 native species, wild American bullfrogs Aquarana catesbeiana, and captive specimens of Ceratophrys ornata and Xenopus laevis. Three haplotypes of the Bd ITS region were identified in native amphibians, all belonging to the global panzootic lineage (BdGPL), of which only one was present in exotic hosts. Despite high infection frequencies in different anurans, we found no evidence of morbidity or mortality attributable to chytridiomycosis, and we observed no discernible impact on body condition or consumed prey. Climatic conditions at the time of our surveys suggested that the chance of infection is associated with monthly mean temperature, mean humidity, and total precipitation. Temperatures below 21°C combined with moderate humidity and pronounced rainfall may increase the likelihood of infection. Multiple haplotypes of BdGPL combined with high frequencies of infection suggest an enzootic pattern in native species, underscoring the need for continued monitoring.

Three new species of the Synapturanus rabus complex (Microhylidae: Otophryninae) in Colombia with a review of the genus Synapturanus.

The Neotropical microhylid genus Synapturanus was represented by only three species for almost five decades and remains poorly known. Recently two new species were described from the Eastern Guyana Shield, one from Peru, and one from Brazil. We describe three new species related to the S. rabus species complex with known distribution only in western Amazonia, Colombia. The S. rabus complex consists of the smallest species in the genus; one of the new species is slightly larger than S. rabus and we describe its full osteology; the other two new species are smaller than S. rabus. We also described the call and larvae of one of the new species. We provide an updated diagnosis and review the available molecular and phenotypic data for the genus.

Larval morphology of Amazonia foam-nesting frogs of the genus Engystomops (Anura: Leptodactylidae: Leiuperinae).

The highly differentiated anuran larvae make them an interesting and complementary source of information to understand anuran evolution. Among neotropical foam-nesting frogs, the available information on tadpole morphology for the subfamily Leiuperinae remains largely incomplete and variably reported among genera; in the monophyletic genus Engystomops it is still incipient. Herein, we summarize available information on larval morphology for five of the nine known species of Engystomops, three of them for the first time, reporting external morphology, buccopharyngeal cavity, and skeleton. The tadpoles of the genus have an overall generalized morphology and many traits are conserved across species. Nevertheless, many characters are systematically informative and some are diagnostic for some species, as the paravertebral gland in Engystomops petersi and the dorsally directed spiracle in Engystomops puyango. Other characters provide support for some subclades within the genus. Moreover, some traits, such as the direction of the vent tube, supports the close relationship between Engystomops and Physalaemus, whereas other support the existence of these two as distinct genera, such as the overall shape of the lateral ridge papillae and the presence of a processus pseudopterygoideus.

Larval chondrocranial and internal oral morphology of the neotropical treefrog Boana crepitans (Wied-Neuwied, 1824; Amphibia, Anura, Hylidae).

We describe the internal oral morphology and chondrocranial anatomy for Boana crepitans tadpoles, and compare them with available descriptions for other species in the subfamily Cophomantinae. Among species of the Boana faber group, the chondrocranial anatomy has been reported only for one species internal oral morphology and cranial anatomy are similar to other described species of Boana and Cophomantinae. B. crepitans lacks unique features in the oral cavity and chondrocranium that would distinguish it from other congeneric species. We identify six characters from the internal oral anatomy of tadpoles unique for Cophomantinae. In addition, Boana has infralabial papillae projections, buccal floor arena papillae, and lateral ridge papillae projections shorter than those described for Aplastodiscus and Bokermannohyla.

Tadpole of the Amazonia frog Edalorhina perezi (Anura: Leptodactylidae) with description of oral internal and chondrocranial morphology.

The genus Edalorhina consists of two species of small forest-floor frogs inhabiting the Amazon basin. The tadpole of Edalorhina perezi, the most widely distributed species, was previously described based on a single and early stage (Gosner 25) individual. Herein, we provide a description of the tadpole in Gosner stages 35-36 including internal morphology data (i.e., buccopharyngeal cavity and larval skeleton) based on samples from two populations from Ecuador. Edalorhina shares a generalized morphology with most members of its closely related taxa; however, it is distinguished from the other species by having an almost terminal oral disc. The presence of a dextral vent tube is considered a synapomorphy for the clade consisting of Edalorhina, Engystomops, and Physalaemus. Within this clade, the combination of two lingual papillae, a filiform median ridge, and the lack of buccal roof papillae are diagnostic of E. perezi and putative autapomorphies of Edalorhina. Chondrocranial anatomy provides characteristics, that is, presence of and uniquely shaped processus pseudopterygoideus and cartilago suprarostralis with corpora and alae joined by dorsal and ventral connections that readily differentiates the genus from other Leiuperinae.

Analysis of ultraconserved elements supports African origins of narrow-mouthed frogs.

Narrow-mouthed frogs (Anura: Microhylidae) are globally distributed and molecular data suggest the rapid evolution of multiple subfamilies shortly after their origin. Despite recent progress, several subfamilial relationships remain unexplored using phylogenomic data. We analysed 1,796 nuclear ultraconserved elements, a total matrix of 400,664 nucleotides, from representatives of most microhylid subfamilies. Summary method species-tree and maximum likelihood analyses unambiguously supported Hoplophryninae as the earliest diverging microhylid and confirm Chaperininae as a junior synonym of Microhylinae. Given the emerging consensus that subfamilies from mainland Africa diverged early, microhylids have likely occupied the continent for more than 66 million years.

The unique traits of the subgenus Unicus within Chiasmocleis Méhely, 1094 (Anura: Microhylidae).

Chiasmocleis is the most speciose genus of Neotropical microhylids. The genus consists of three monophyletic clades that were recently recognized as subgenera. Within Chiasmocleis, the subgenus Unicus has a basal position in the phylogeny and contains a single species that occurs in the North Atlantic Forest of Brazil, isolated from the ranges of other Chiasmocleis. However, the subgenus Unicus lacked a formal description and consequently so far was a nomen nudum. Herein, we provide a diagnosis (i.e., morphological and molecular apomorphies) of the subgenus Unicus de Sá, Tonini, van Huss, Long, Cuddy, Forlani, Peloso, Zaher and Haddad, 2019b; for convenience, the name has also been registered in ZooBank.

Multiple connections between Amazonia and Atlantic Forest shaped the phylogenetic and morphological diversity of Chiasmocleis Mehely, 1904 (Anura: Microhylidae: Gastrophryninae).

Chiasmocleis is the most species-rich genus of Neotropical microhylids. Herein, we provide the first comprehensive multilocus phylogeny for the genus, including all but 3 of the 34 recognized species and multiple individuals per species. We discuss cryptic speciation, species discovery, patterns of morphological evolution, and provide a historical biogeographic analysis to account for the current distribution of the genus. Diversification of Chiasmocleis from other New World microhylids began during the Eocene, app. 40 mya, in forested areas, and current diversity seems to be a product of recurrent connections between the Atlantic Forest and Amazonia. Small-sized species evolved independently three times in Chiasmocleis. Furthermore, the extremely small-bodied (i.e. miniaturized) species with associated loss of digits, phalanges, and pectoral girdle cartilages evolved only once and are restricted to Amazonia. Using the phylogeny, we recognized three subgenera within Chiasmocleis: Chiasmocleis Méhely, 1904, Relictus subg. nov., and Syncope Walker, 1973. The recognition of the subgenus Syncope informs future research on patterns of miniaturization in the genus, and the subgenus Relictus highlights isolation of an endemic and species-poor lineage to the Atlantic Forest, early (about 40 mya) in the history of Chiasmocleis.

Molecular insights into the phylogenetic placement of the poorly known genus Niceforonia Goin Cochran, 1963 (Anura: Brachycephaloidea).

Among New World direct-developing frogs belonging to the clade Brachycephaloidea (= Terraranae), there are several genera with uncertain phylogenetic placements. One notable example is the genus Niceforonia Goin Cochran 1963, which includes three species that are endemic to Colombia. Three specimens of the species Niceforonia nana were collected and for the first time the genus is included in a molecular phylogenetic analysis of mitochondrial (mtDNA; 12S and 16S) and nuclear (nucDNA; TYR and RAG1) markers. Molecular phylogenetic inference based on concatenated and separate mtDNA and nucDNA analyses recovered Niceforonia nana nested within Hypodactylus Hedges et al. 2008, rendering the latter genus paraphyletic. Consequently, herein we place the genus Hypodactylus in the synonymy of Niceforonia to resolve the paraphyly and place Niceforonia in the subfamily Hypodactylinae. Based on our revised concept of the genus Niceforonia we conducted preliminary morphological comparisons using specimens and literature descriptions. Finally, Nicefornia nana is quite divergent from other species of Niceforonia (uncorrected genetic distances of ca. 10% 16S and 7% TYR) suggesting that further taxonomic revision may be warranted.

Leptodactylus validus Garman, 1888 in Colombia: its distribution and identification.

Leptodactylus validus is reported for the first time for Colombia, corresponding to the tenth species of the L. melanonotus species group occurring in the country. In collections, all L. validus specimens were identified as L. colombiensis. Morphological, coloration, and ecological characters are provided to differentiate the two species in Colombia. Furthermore, the distribution of L. validus is expanded based on the examination of specimens in both collections and literature records. In addition, the advertisement call of L. validus from Colombia is compared with those reported for other continental and insular populations; the calls are slightly more similar to those of insular populations.

Molecular and morphological data reveal three new cryptic species of Chiasmocleis (Mehely 1904) (Anura, Microhylidae) endemic to the Atlantic Forest, Brazil.

Three new cryptic species of Chiasmocleis from the Atlantic Forest of Brazil are described. Two of these species occur in the northeastern states of Sergipe and Bahia, whereas the third species is found in the southeastern state of São Paulo. The new species can be distinguished from other congeneric species by the molecular data, as evidenced in the phylogeny, and by a combination of morphological characters including: size, foot webbing, dermal spines, and coloration patterns. Chiasmocleis species differ in osteological traits, therefore we also provide an osteological description of each new species and comparsions with data reported for other species in the genus.

High genetic diversity but low population structure in the frog Pseudopaludicola falcipes (Hensel, 1867) (Amphibia, Anura) from the Pampas of South America.

Relative to South America's ecoregions, the temperate grasslands of the Pampas have been poorly studied from a phylogeographic perspective. Based on an intermediate biogeographic setting between subtropical forest (Atlantic Forest) and arid ecosystems (Chaco and Patagonia), Pampean species are expected to show unstable demographic histories due to the Quaternary climatic oscillations. Herein, we investigate the phylogenetic relatedness and phylogeographic history of Pseudopaludicola falcipes, a small and common frog that is widely distributed across the Pampean grasslands. First, we use molecular data to assess if P. falcipes represents a single or multiple, separately evolving cryptic lineages. Because P. falcipes is a small-size species (<20mm) with extensive coloration and morphological variation, we suspected that it might represent a complex of cryptic species. In addition, we expected strong genetic and geographic structuring within Pseudopaludicola falcipes due to its large geographic distribution, potentially short dispersal distances, and multiple riverine barriers. We found that P. falcipes is a single evolutionary lineage with poor geographic structuring. Furthermore, current populations of P. falcipes have a large effective population size, maintain ancestral polymorphisms, and have a complex network of gene flow. We conclude that the demographic history of P. falcipes, combined with its ecological attributes and the landscape features of the Pampas, favored a unique combination among anurans of small body size, large population size, high genetic variability, but high cohesiveness of populations over a wide geographic distribution.

Comments on the type locality, type series, and geographic distribution of Pseudopaludicola falcipes (Hensel, 1867) (Amphibia, Anura).

The genus Pseudopaludicola was erected by Miranda-Ribeiro, 1926 to accommodate Liuperus falcipes Hensel, 1867a. Currently, there are 18 recognized species of Pseudopaludicola, with 45% of the species described since 2003. Although Pseudopaludicola falcipes is the type species, Hensel's description lacked designation of type specimens for that species; furthermore, it was based on a series of 30 individuals (without collection numbers or indication of where were they deposited) from "Provinz S[ão]. Pedro do Rio Grande do Sul" (today Rio Grande do Sul State, Brazil).

A new species of Chiasmocleis (Microhylidae, Gastrophryninae) from the Atlantic Forest of Espírito Santo State, Brazil.

Among Neotropical microhylids, the genus Chiasmocleis is exceptionally diverse. Most species of Chiasmocleis were described in recent years based on external morphology, but recent studies using molecular data did not support the monophyly of the species groups clustered based on feet webbing. Furthermore, a phylogeographic study of C. lacrimae estimated high genetic divergence and low gene flow among populations across small geographic ranges. Increasing the molecular and geographic sampling, and incorporating morphological data, we identified new cryptic species. Herein, we used novel genetic and morphological data to describe a new species of Chiasmocleis.

The identity of Rana margaritifera Laurenti, 1768 (Anura, Bufonidae).

Rana margaritifera was described by Laurenti in 1768 and currently is associated to the genus Rhinella, under the combination Rhinella margaritifera. Currently, the R. margaritifera species group consists of 16 recognized species. Furthermore, many additional species have been suggested to exist in this group which highlights the ambiguity surrounding the identity of Rhinella margaritifera and impend further description of the species in this group. After an exhaustive bibliographic review, we concluded that the recent designation of a lectotype for R. margaritifera is invalid according with Art. 73, ICZN, 1999. Herein, we designate and provide the description of a neotype for Rana margaritifera Laurenti, 1768.

Molecular phylogeny of microhylid frogs (Anura: Microhylidae) with emphasis on relationships among New World genera.

BACKGROUND: Over the last ten years we have seen great efforts focused on revising amphibian systematics. Phylogenetic reconstructions derived from DNA sequence data have played a central role in these revisionary studies but have typically under-sampled the diverse frog family Microhylidae. Here, we present a detailed phylogenetic study focused on expanding previous hypotheses of relationships within this cosmopolitan family. Specifically, we placed an emphasis on assessing relationships among New World genera and those taxa with uncertain phylogenetic affinities (i.e., incertae sedis). RESULTS: One mitochondrial and three nuclear genes (about 2.8 kb) were sequenced to assess phylogenetic relationships. We utilized an unprecedented sampling of 200 microhylid taxa representing 91% of currently recognized subfamilies and 95% of New World genera. Our analyses do not fully resolve relationships among subfamilies supporting previous studies that have suggested a rapid early diversification of this clade. We observed a close relationship between Synapturanus and Otophryne of the subfamily Otophryninae. Within the subfamily Gastrophryninae relationships between genera were well resolved. CONCLUSION: Otophryninae is distantly related to all other New World microhylids that were recovered as a monophyletic group, Gastrophryninae. Within Gastrophryninae, five genera were recovered as non-monophyletic; we propose taxonomic re-arrangements to render all genera monophyletic. This hypothesis of relationships and updated classification for New World microhylids may serve as a guide to better understand the evolutionary history of this group that is apparently subject to convergent morphological evolution and chromosome reduction. Based on a divergence analysis calibrated with hypotheses from previous studies and fossil data, it appears that microhylid genera inhabiting the New World originated during a period of gradual cooling from the late Oligocene to mid Miocene.

Rapid range expansion in the Great Plains narrow-mouthed toad (Gastrophryne olivacea) and a revised taxonomy for North American microhylids.

We investigated genetic variation within the Great Plains narrow-mouthed toad, Gastrophryne olivacea, across its geographic range in the United States and Mexico. An analysis of mitochondrial DNA (mtDNA) from 105 frogs revealed remarkably low levels of genetic diversity in individuals inhabiting the central United States and northern Mexico. We found that this widespread matrilineal lineage is divergent (ca. 2% in mtDNA) from haplotypes that originate from the western United States and western coast of Mexico. Using a dataset that included all five species of Gastrophryne and both species of the closely related genus Hypopachus, we investigated the phylogenetic placement of G. olivacea. This analysis recovered strong support that G. olivacea, the tropically distributed G. elegans, and the temperately distributed G. carolinensis constitute a monophyletic assemblage. However, the placement of G. pictiventris and G. usta render Gastrophryne paraphyletic with respect to Hypopachus. To complement our mitochondrial analysis, we examined a small fragment of nuclear DNA and recovered consistent patterns. In light of our findings we recommend (1) the resurrection of the nomen G. mazatlanensisTaylor (1943) for the disjunct western clade of G. olivacea and (2) the tentative placement of G. pictiventris and G. usta in Hypopachus. To explore possible scenarios leading to low levels of genetic diversity in G. olivacea, we used mismatch distributions and Bayesian Skyline plots to examine historic population expansion and demography. Collectively these analyses suggest that G. olivacea rapidly expanded in effective population size and geographic range during the late Pleistocene or early Holocene. This hypothesis is consistent with fossil data from northern localities and contemporary observations that suggest ongoing northern expansion. Given our findings, we suspect that the rapid range expansion of G. olivacea may have been facilitated by ecological associations with open habitats and seasonal water bodies.

Molecular systematics of the Middle American genus Hypopachus (Anura: Microhylidae).

We present the first phylogenetic study on the widespread Middle American microhylid frog genus Hypopachus. Partial sequences of mitochondrial (12S and 16S ribosomal RNA) and nuclear (rhodopsin) genes (1275 bp total) were analyzed from 43 samples of Hypopachus, three currently recognized species of Gastrophryne, and seven arthroleptid, brevicipitid and microhylid outgroup taxa. Maximum parsimony (PAUP), maximum likelihood (RAxML) and Bayesian inference (MrBayes) optimality criteria were used for phylogenetic analyses, and BEAST was used to estimate divergence dates of major clades. Population-level analyses were conducted with the programs NETWORK and Arlequin. Results confirm the placement of Hypopachus and Gastrophryne as sister taxa, but the latter genus was strongly supported as paraphyletic. The African phrynomerine genus Phrynomantis was recovered as the sister taxon to a monophyletic Chiasmocleis, rendering our well-supported clade of gastrophrynines paraphyletic. Hypopachus barberi was supported as a disjunctly distributed highland species, and we recovered a basal split in lowland populations of Hypopachus variolosus from the Pacific versant of Mexico and elsewhere in the Mesoamerican lowlands. Dating analyses from BEAST estimate speciation within the genus Hypopachus occurred in the late Miocene/early Pliocene for most clades. Previous studies have not found bioacoustic or morphological differences among these lowland clades, and our molecular data support the continued recognition of two species in the genus Hypopachus.

Phylogeography of the frog Leptodactylus validus (Amphibia: Anura): patterns and timing of colonization events in the Lesser Antilles.

The frog Leptodactylus validus occurs in northern South America, Trinidad and Tobago, and the southern Lesser Antilles (Grenada and St. Vincent). Mitochondrial DNA sequences were used to perform a nested clade phylogeographic analysis (NCPA), to date colonization events, and to analyze colonization patterns using on a relaxed molecular clock and coalescent simulations. L. validus originated on the mainland and first colonized Trinidad with subsequent independent colonizations of Tobago and the Lesser Antilles from Trinidad. The NCPA suggests a historical vicariant event between populations in Trinidad and Tobago from those in the Lesser Antilles. The colonization of Trinidad occurred approximately 1 million years ago (mya) and the colonization of the Lesser Antillean islands occurred approximately 0.4 mya. The coalescent approach supported the scenario where L. validus dispersed from Trinidad to St. Vincent and from there to Grenada, a dispersal event that could have been mediated by human introduction as recent as 1600 years ago.