Underestimation of species richness in neotropical frogs revealed by mtDNA analyses

Morphological diversification of Mediterranean anurans: the roles of evolutionary history and climate

Investigation of the ecological and evolutionary mechanisms governing the origin and diversification of species requires integrative approaches that often have to accommodate strong discordance among datasets. A common source of conflict is the combination of morphological and molecular characters with different evolutionary rates. Resolution of these discordances is crucial to assess the relative roles of different processes in generating and maintaining biodiversity. Anuran amphibians provide many examples of morphologically similar, genetically divergent lineages, posing questions about the relative roles of phylogeny and ecological factors in phenotypic evolution. We focused on three circum-Mediterranean anuran genera (Hyla, Alytes and Discoglossus), characterizing morphological and environmental disparity and comparing diversity patterns across biological levels of organization. Using a comparative phylogenetic framework, we tested how shared ancestry and climatic factors come together to shape phenotypic diversity. We found higher morphological differentiation within Hyla and Alytes than in Discoglossus. Body size and limb morphology contributed most to inter- and intraspecific morphological variation in Hyla and Alytes, but there was no strong phylogenetic signal, indicating that shared ancestry does not predict patterns of phenotypic divergence. In contrast, we uncovered a significant association between morphology and climatic descriptors, supporting the hypothesis that morphological disparity between species results from adaptive evolution.

Pristimantis achupalla sp. n., a new minute species of direct-developing frog (Amphibia, Anura, Strabomantidae) inhabiting bromeliads of the montane forest of the Amazonian Andes of Puno, Peru

We describe a new species of bromeliad-dwelling Pristimantis from primary montane forest (2,225 m a.s.l.) in southern Peru. The type locality is near Thiuni, in the Department of Puno (province of Carabaya) in the upper watershed of a tributary of the Inambari River. Pristimantis achupalla sp. n. is characterized by a snout-vent length of 10.0–12.8 mm in adult males (n = 4), unknown in adult females, and is compared morphologically and genetically with species in the Pristimantis lacrimosus group, and with other similar species of Pristimantis. The new species is characterized by having skin on dorsum and flanks rugose, green brownish color, distinctive scapular folds, subacuminate or acuminate snout profile, upper eyelid bearing two or three subconical tubercles and some rounded tubercles, rostral papilla, flanks light brown to brown, with irregular dark brown marks.

The role of vicariance and dispersal on the temporal range dynamics of forest vipers in the Neotropical region

The emergence of the diagonal of open/dry vegetations, including Chaco, Cerrado and Caatinga, is suggested to have acted as a dispersal barrier for terrestrial organisms by fragmenting a single large forest that existed in South America into the present Atlantic and Amazon forests. Here we tested the hypothesis that the expansion of the South American diagonal of open/dry landscapes acted as a vicariant process for forest lanceheads of the genus Bothrops, by analyzing the temporal range dynamics of those snakes. We estimated ancestral geographic ranges of the focal lancehead clade and its sister clade using a Bayesian dated phylogeny and the BioGeoBEARS package. We compared nine Maximum Likelihood models to infer ancestral range probabilities and their related biogeographic processes. The best fitting models (DECTS and DIVALIKETS) recovered the ancestor of our focal clade in the Amazon biogeographic region of northwestern South America. Vicariant processes in two different subclades resulted in disjunct geographic distributions in the Amazon and the Atlantic Forest. Dispersal processes must have occurred mostly within the Amazon and the Atlantic Forest and not between them. Our results suggest the fragmentation of a single ancient large forest into the Atlantic and Amazon forests acting as a driver of vicariant processes for the snake lineage studied, highlighting the importance of the diagonal of open/dry landscapes in shaping distribution patterns of terrestrial biota in South America.

The phylogeny of the Casque-headed Treefrogs (Hylidae: Hylinae: Lophyohylini)

The South American and West Indian Casque-headed Treefrogs (Hylidae: Hylinae: Lophyohylini) include 85 species. These are notably diverse in morphology (e.g. disparate levels of cranial hyperossification) and life history (e.g. different reproductive modes, chemical defences), have a wide distribution, and occupy habitats from the tropical rainforests to semiarid scrubland. In this paper, we present a phylogenetic analysis of this hylid tribe based on sequence fragments of up to five mitochondrial (12S, 16S, ND1, COI, Cytb) and six nuclear genes (POMC, RAG-1, RHOD, SIAH, TNS3, TYR). We included most of its species (> 96%), in addition to a number of new species. Our results indicate: (i) the paraphyly of Trachycephalus with respect to Aparasphenodon venezolanus; (ii) the nonmonophyly of Aparasphenodon, with Argenteohyla siemersi, Corythomantis galeata and Nyctimantis rugiceps nested within it, and Ap. venezolanus nested within Trachycephalus; (iii) the polyphyly of Corythomantis; (iv) the nonmonophyly of the recognized species groups of Phyllodytes; and (v) a pervasive low support for the deep relationships among the major clades of Lophyohylini, including C. greeningi and the monotypic genera Itapotihyla and Phytotriades. To remedy the nonmonophyly of Aparasphenodon, Corythomantis, and Trachycephalus, we redefined Nyctimantis to include Aparasphenodon (with the exception of Ap. venezolanus, which we transferred to Trachycephalus), Argenteohyla, and C. galeata. Additionally, our results indicate the need for taxonomic work in the following clades: (i) Trachycephalus dibernardoi and Tr. imitatrix; (ii) Tr. atlas, Tr. mambaiensis and Tr. nigromaculatus; and (iii) Phyllodytes. On the basis of our phylogenetic results, we analyzed the evolution of skull hyperossification and reproductive biology, with emphasis on the multiple independent origins of phytotelm breeding, in the context of Anura. We also analyzed the inter-related aspects of chemical defences, venom delivery, phragmotic behaviour, co-ossification, and prevention of evaporative water loss.

The Pristimantis trachyblepharis species group, a clade of miniaturized frogs: description of four new species and insights into the evolution of body size in the genus

Species richness in the genus Pristimantis is underestimated due to the existence of morphologically cryptic species. This is worsened by the low sampling effort and the lack of studies using genetic markers. Here, we use molecular and morphological data to determine the phylogenetic relationships of a clade of Pristimantis distributed throughout montane tropical forests in the eastern Andes, from central Ecuador to northern Perú. We name this clade the Pristimantis trachyblepharis species group. Our results show that it comprises nine species, of which four are formally described and five are new. Four of these undescribed species are formally described here. The group is composed of miniaturized species, such as Pristimantis nanus sp. nov., currently the smallest known species of the genus and the smallest vertebrate in Ecuador. As a first approach to understanding the evolutionary origin and implications of body-size reduction in Pristimantis, we here study the phylogenetic signal and evolutionary trends of body size within the genus. We also provide the first record of P. aquilonaris in Ecuador and we show, for the first time, the phylogenetic position of P. albujai, P. aquilonaris, P. minimus and P. trachyblepharis, which are also members of the P. trachyblepharis species group.

A new species of the Dendropsophus decipiens Group (Anura: Hylidae) from Northeastern Brazil

We describe a new species of the Dendropsophus decipiens Group, morphologically most resembling D. haddadi but genetically more closely related to D. oliveirai and likely endemic from the Atlantic Forest biome, northeastern Brazil. The new species can be distinguished from all species of the D. decipiens Group based on the combination of morphological features, advertisement call and phylogenetic position based on mitochondrial DNA gene sequences. The new species emits simple calls in series of 3-9 notes, each with 9-29 pulses, and dominant frequency varying from 5578-6422 Hz, and exhibit a minimum of 8% genetic distance (16S mitochondrial gene) in comparison to its congeners. The new taxa represent the sixth species of the D. decipiens Group, which likely harbors more undescribed taxa, corroborating the view that Neotropical species richness is fairly underestimated.

A new critically endangered slippery frog (Amphibia, Conrauidae, Conraua) from the Atewa Range, central Ghana

Forty-nine years after the last description of a slippery frog, we describe a seventh species of the genus Conraua. The new Conraua is endemic to the Atewa Range Forest Reserve, central Ghana, and is described based on genetic, bioacoustics, and morphological evidence. Recent molecular phylogenetic and species delimitation analyses support this population as distinct from nominotypical C. derooi in eastern Ghana and adjacent Togo. The new species is sister to C. derooi, from which it differs ~4% in the DNA sequence for mitochondrial ribosomal 16S. Genetic divergences in 16S to other species of Conraua range from 412%. The new species is distinguished morphologically from its congeners, including C. derooi, by the combination of the following characters: medium body size, robust limbs, lateral dermal fringing along edges of fingers, cream ventral color with brown mottling, the presence of a lateral line system, indistinct tympanum, the presence of inner, outer, and middle palmar tubercles, and two subarticular tubercles on fingers III and IV. We compare the advertisement calls of the new species with the calls from C. derooi and find that they differ by duration, frequency modulation, and dominant frequency. We discuss two potential drivers of speciation between C. derooi and the new species, including river barriers and fragmentation of previously more widespread forests in West Africa. Finally, we highlight the importance of the Atewa Range Forest Reserve as a critical conservation area within the Upper Guinean biodiversity hotspot.

A species of the genus Panophrys (Anura, Megophryidae) from southeastern Guizhou Province, China

Herein, we describe Panophryscongjiangensissp. nov. obtained from the Yueliangshan Nature Reserve, Congjiang County, Guizhou Province, China. Phylogenetic analyses based on the mitochondrial genes 16S rRNA and COI indicated that this new species represented an independent lineage, closely related to P.leishanensis. The uncorrected genetic distances between the new species and its closest congener, P.leishanensis, were 3.0% for 16S rRNA and 8.4% for COI. The new species is distinguished from its congeners by a combination of the following morphological characteristics (1) medium body size (SVL 28.6–33.4 mm in males and 38.4–40.2 mm in females); (2) a small horn-like tubercle at the edge of each upper eyelid; (3) the tympanum distinctly visible (TD/ED ratio 0.47–0.66); (4) vomerine teeth absent; (5) the tongue not notched behind; (6) a narrow and unobvious lateral fringe on toes; (7) relative finger lengths II < I < V < III; (8) rudimentary webs on toes; (9) hindlimbs slender, heels overlapping when thighs are positioned at right angles to the body; (10) two metacarpal tubercles on the palm, with the inner metatarsal tubercle long and oval-shaped; (11) the tibiotarsal articulation reaching the nostril when the leg is adpressed and stretched forward; (12) dorsal skin rough with numerous orange–red granules, ventral surface smooth; (13) a single internal subgular vocal sac present in males; and (14) in breeding males, weak gray-black nuptial pads with black nuptial spines present on the dorsal surface of the bases of the first and second fingers. To date, the new species is only known from the type locality.

Unexpectedly high levels of lineage diversity in Sundaland puddle frogs (Dicroglossidae: Occidozyga Kuhl and van Hasselt, 1822)

One of the most urgent contemporary tasks for taxonomists and evolutionary biologists is to estimate the number of species on earth. Recording alpha diversity is crucial for protecting biodiversity, especially in areas of elevated species richness, which coincide geographically with increased anthropogenic environmental pressures - the world's so-called biodiversity hotspots. Although the distribution of Puddle frogs of the genus Occidozyga in South and Southeast Asia includes five biodiversity hotspots, the available data on phylogeny, species diversity, and biogeography are surprisingly patchy. Samples analyzed in this study were collected throughout Southeast Asia, with a primary focus on Sundaland and the Philippines. A mitochondrial gene region comprising ~ 2000 bp of 12S and 16S rRNA with intervening tRNA Valine and three nuclear loci (BDNF, NTF3, POMC) were analyzed to obtain a robust, time-calibrated phylogenetic hypothesis. We found a surprisingly high level of genetic diversity within Occidozyga, based on uncorrected p-distance values corroborated by species delimitation analyses. This extensive genetic diversity revealed 29 evolutionary lineages, defined by the > 5% uncorrected p-distance criterion for the 16S rRNA gene, suggesting that species diversity in this clade of phenotypically homogeneous forms probably has been underestimated. The comparison with results of other anuran groups leads to the assumption that anuran species diversity could still be substantially underestimated in Southeast Asia in general. Many genetically divergent lineages of frogs are phenotypically similar, indicating a tendency towards extensive morphological conservatism. We present a biogeographic reconstruction of the colonization of Sundaland and nearby islands which, together with our temporal framework, suggests that lineage diversification centered on the landmasses of the northern Sunda Shelf. This remarkably genetically structured group of amphibians could represent an exceptional case for future studies of geographical structure and diversification in a widespread anuran clade spanning some of the most pronounced geographical barriers on the planet (e.g., Wallace's Line). Studies considering gene flow, morphology, ecological and bioacoustic data are needed to answer these questions and to test whether observed diversity of Puddle frog lineages warrants taxonomic recognition.

Gene Flow Increases Phylogenetic Structure and Inflates Cryptic Species Estimations: A Case Study on Widespread Philippine Puddle Frogs (Occidozyga laevis)

In cryptic amphibian complexes, there is a growing trend to equate high levels of genetic structure with hidden cryptic species diversity. Typically, phylogenetic structure and distance-based approaches are used to demonstrate the distinctness of clades and justify the recognition of new cryptic species. However, this approach does not account for gene flow, spatial, and environmental processes that can obfuscate phylogenetic inference and bias species delimitation. As a case study, we sequenced genome-wide exons and introns to evince the processes that underlie the diversification of Philippine Puddle Frogs-a group that is widespread, phenotypically conserved, and exhibits high levels of geographically-based genetic structure. We showed that widely adopted tree- and distance-based approaches inferred up to 20 species, compared to genomic analyses that inferred an optimal number of five distinct genetic groups. Using a suite of clustering, admixture, and phylogenetic network analyses, we demonstrate extensive admixture among the five groups and elucidate two specific ways in which gene flow can cause overestimations of species diversity: (1) admixed populations can be inferred as distinct lineages characterized by long branches in phylograms; and (2) admixed lineages can appear to be genetically divergent, even from their parental populations when simple measures of genetic distance are used. We demonstrate that the relationship between mitochondrial and genome-wide nuclear p-distances is decoupled in admixed clades, leading to erroneous estimates of genetic distances and, consequently, species diversity. Additionally, genetic distance was also biased by spatial and environmental processes. Overall, we showed that high levels of genetic diversity in Philippine Puddle Frogs predominantly comprise metapopulation lineages that arose through complex patterns of admixture, isolation-by-distance, and isolation-by-environment as opposed to species divergence. Our findings suggest that speciation may not be the major process underlying the high levels of hidden diversity observed in many taxonomic groups and that widely-adopted tree- and distance-based methods overestimate species diversity in the presence of gene flow.

Exploring the vertebrate fauna of the Bird's Head Peninsula (Indonesia, West Papua) through DNA barcodes

Biodiversity knowledge is widely heterogeneous across the Earth's biomes. Some areas, due to their remoteness and difficult access, present large taxonomic knowledge gaps. Mostly located in the tropics, these areas have frequently experienced a fast development of anthropogenic activities during the last decades and are therefore of high conservation concerns. The biodiversity hotspots of Southeast Asia exemplify the stakes faced by tropical countries. While the hotspots of Sundaland (Java, Sumatra, Borneo) and Wallacea (Sulawesi, Moluccas) have long attracted the attention of biologists and conservationists alike, extensive parts of the Sahul area, in particular the island of New Guinea, have been much less explored biologically. Here, we describe the results of a DNA-based inventory of aquatic and terrestrial vertebrate communities, which was the objective of a multidisciplinary expedition to the Bird's Head Peninsula (West Papua, Indonesia) conducted between 17 October and 20 November 2014. This expedition resulted in the assembly of 1005 vertebrate DNA barcodes. Based on the use of multiple species-delimitation methods (GMYC, PTP, RESL, ABGD), 264 molecular operational taxonomic units (MOTUs) were delineated, among which 75 were unidentified and an additional 48 were considered cryptic. This study suggests that the diversity of vertebrates of the Bird's Head is severely underestimated and considerations on the evolutionary origin and taxonomic knowledge of these biotas are discussed.

Beauty is in the eye of the beholder: Cruciform eye reveals new species of direct-developing frog (Strabomantidae, Pristimantis) in the Amazonian Andes

We describe a new species of frog from the eastern slopes of the Andes in central Peru. Pristimantis sirasp. nov. has a distinctive crossing mark on the iris and no tympanum. The new species is closely related to P. antisuyu Catenazzi &amp; Lehr, 2018, P. cruciocularis Lehr, Lundberg, Aguilar &amp; von May, 2006, and P. erythroinguinis Catenazzi &amp; Lehr, 2018, but is easily differentiable by lacking colour blotches on groins. Pristimantis sirasp. nov. inhabits the mountain forests from 1550 to 2200 m a.s.l., inside a national reserve threatened by illegal mining.

Current and Forthcoming Approaches for Benchmarking Genetic and Genomic Diversity

The current attrition of biodiversity extends beyond loss of species and unique populations to steady loss of a vast genomic diversity that remains largely undescribed. Yet the accelerating development of new techniques allows us to survey entire genomes ever faster and cheaper, to obtain robust samples from a diversity of sources including degraded DNA and residual DNA in the environment, and to address conservation efforts in new and innovative ways. Here we review recent studies that highlight the importance of carefully considering where to prioritize collection of genetic samples (e.g., organisms in rapidly changing landscapes or along edges of geographic ranges) and what samples to collect and archive (e.g., from individuals of little-known subspecies or populations, even of species not currently considered endangered). Those decisions will provide the sample infrastructure to detect the disappearance of certain genotypes or gene complexes, increases in inbreeding levels, and loss of genomic diversity as environmental conditions change. Obtaining samples from currently endangered, protected, and rare species can be particularly difficult, thus we also focus on studies that use new, non-invasive ways of obtaining genomic samples and analyzing them in these cases where other sampling options are highly constrained. Finally, biological collections archiving such samples face an inherent contradiction: their main goal is to preserve biological material in good shape so it can be used for scientific research for centuries to come, yet the technologies that can make use of such materials are advancing faster than collections can change their standardized practices. Thus, we also discuss current and potential new practices in biological collections that might bolster their usefulness for future biodiversity conservation research.

Cytogenetic and genetic data support Crossodactylus aeneus Müller, 1924 as a new junior synonym of C. gaudichaudii Duméril and Bibron, 1841 (Amphibia, Anura)

The nominal anuran species Crossodactylus gaudichaudii Duméril and Bibron, 1841 and Crossodactylus aeneus Müller, 1924 are indistinguishable based on adult and larval morphology, being subject of taxonomic doubts. Here, we describe the karyotypes of C. gaudichaudii and C. aeneus, using classical and molecular cytogenetic markers. In addition, we used sequences of the H1 mitochondrial DNA to infer their phylogenetic relationships by Maximum Likelihood (ML) and Maximum Parsimony (MP) approaches and species delimitation test (by bPTP approach). The karyotypic data do not differentiate C. gaudichaudii and C. aeneus in any of the chromosome markers assessed. In both phylogenetic analyses, C. gaudichaudii and C. aeneus were recovered into a strongly supported clade. The species delimitation analysis recovered the specimens assigned to C. gaudichaudii and C. aeneus as a single taxonomic unit. Taken the cytogenetic and genetic results together with previous studies of internal and external morphology of tadpoles and biacoustic pattern, C. gaudichaudii and C. aeneus could not be differentiated, which supports the hypothesis that they correspond to the same taxonomic unit, with C. aeneus being a junior synonym of C. gaudichaudii.

A new species of the Asian leaf litter toad genus Leptobrachella Smith, 1925 (Anura, Megophryidae) from northwest Guizhou Province, China

A new species of the Asian leaf litter toad genus Leptobrachella is described from Guizhou Province, China. Molecular phylogenetic analyses support the new species as an independent lineage deeply nested in the Leptobrachella clade. The new species is distinguished from its congeners by a combination of the following morphological characters: body size medium (SVL 29.7–31.2 mm in five adult males); dorsal skin shagreened, some of the granules forming longitudinal short skin ridges; tympanum distinctly discernible, slightly concave; supra-axillary, femoral, pectoral and ventrolateral glands distinctly visible; absence of webbing and lateral fringes on fingers; toes with narrow lateral fringes but without webbing; heels overlapping when thighs are positioned at right angles to the body; tibia-tarsal articulation reaching the middle of eye when leg stretched forward. The discovery highlighted the underestimated species diversity in the Leptobrachella toads in southwestern China.

Species diversity and biogeography of an ancient frog clade from the Guiana Shield (Anura: Microhylidae: Adelastes, Otophryne, Synapturanus) exhibiting spectacular phenotypic diversification

The outstanding biodiversity of the Guiana Shield has raised many questions about its origins and evolution. Frogs of the genera Adelastes, Otophryne and Synapturanus form an ancient lineage distributed mostly across this region. These genera display strikingly disparate morphologies and life-history traits. Notably, Synapturanus is conspicuously adapted to fossoriality and is the only genus within this group to have dispersed further into Amazonia. Moreover, morphological differences among Synapturanus species suggest different degrees of fossoriality that might be linked to their biogeographical history. Through integrative analysis of genetic, morphometric and acoustic data, we delimited 25 species in this clade, representing a fourfold increase. We found that the entire clade started to diversify ~55 Mya and Synapturanus ~30 Mya. Members of this genus probably dispersed three times out of the Guiana Shield both before and after the Pebas system, a wetland ecosystem occupying most of Western Amazonia during the Miocene. Using a three-dimensional osteological dataset, we characterized a high morphological disparity across the three genera. Within Synapturanus, we further characterized distinct phenotypes that emerged concomitantly with dispersals during the Miocene and possibly represent adaptations to different habitats, such as soils with different physical properties.

A New Species of Micryletta (Amphibia: Anura) from Sumatra, Indonesia

Micryletta inornata is a complex species that is widely distributed from Sumatra to mainland Asia, including the Thai-Malay Peninsula and Indochina. Recently, this species was confirmed to be endemic to regions near the type locality in Sumatra, and the populations from other regions were suggested to be different species. We examined phenotypic and genotypic characters of the Sumatran populations and found an unnamed lineage in addition to the true M. inornata. The newly found lineage can be distinguished from M. inornata and other congeners by both molecular and morphological traits and has been named Micryletta sumatrana sp. nov. The new species is characterized by having a small body size, golden brown dorsum with scattered dark spots, dark brown ventrum with diffuse cream mottling, dark brown lateral head with cream spots on lips and the tympanum region extending to the axilla, and tibiotarsal articulation reaching to the front of the eye. We discuss the taxonomic status of so-called M. inornata occurring outside of its type locality, especially of M. inornata lineata.

Sex chromosome evolution in frogs-helpful insights from chromosome painting in the genus Engystomops

The differentiation of sex chromosomes is thought to be interrupted by relatively frequent sex chromosome turnover and/or occasional recombination between sex chromosomes (fountain-of-youth model) in some vertebrate groups as fishes, amphibians, and lizards. As a result, we observe the prevalence of homomorphic sex chromosomes in these groups. Here, we provide evidence for the loss of sex chromosome heteromorphism in the Amazonian frogs of the genus Engystomops, which harbors an intriguing history of sex chromosome evolution. In this species complex composed of two named species, two confirmed unnamed species, and up to three unconfirmed species, highly divergent karyotypes are present, and heteromorphic X and Y chromosomes were previously found in two species. We describe the karyotype of a lineage estimated to be the sister of all remaining Amazonian Engystomops (named Engystomops sp.) and perform chromosome painting techniques using one probe for the Y chromosome and one probe for the non-centromeric heterochromatic bands of the X chromosome of E. freibergi to compare three Engystomops karyotypes. The Y probe detected the Y chromosomes of E. freibergi and E. petersi and one homolog of chromosome pair 11 of Engystomops sp., suggesting their common evolutionary origin. The X probe showed no interspecific hybridization, revealing that X chromosome heterochromatin is strongly divergent among the studied species. In the light of the phylogenetic relationships, our data suggest that sex chromosome heteromorphism may have occurred early in the evolution of the Amazonian Engystomops and have been lost in two unnamed but confirmed candidate species.

Phylogenetic relationships of the Boana pulchella Group (Anura: Hylidae)

In this paper we present a phylogenetic analysis of the treefrogs of the Boana pulchella Group with the goals of (1) providing a rigorous test of its monophyly; (2) providing a test of relationships supported in previous studies; and (3) exploring the relationships of the several species not included in previous analyses. The analyses included>300 specimens of 37 of the 38 species currently included in the group, plus 36 outgroups, exemplars of the diversity of Boana and the other genera of the hylid tribe Cophomantini. The dataset included eight mitochondrial genes (12S, 16S, CytB, COI, ND1, tRNA^Ile, tRNA^Leu, and tRNA^Val) and five nuclear genes (RHO, TYR, RAG-1, CXCR4, SIAH1). The phylogenetic analyses recover the monophyly of the B. pulchella Group with lower support than previous studies, as a result of the inclusion of the B. claresignata Group, which is recovered as its sister taxon. Within the B. pulchella Group, the inclusion of almost all species of the group had little impact on previous notions of its phylogeny, except for the rejection of the hypothesized B. polytaenia Clade (B. goiana and B. phaeopleura are nested in the clade here called the B. prasina Clade), which is redefined. Phylogenetic support is strong for five major clades, which collectively include all but three of the species sampled: the B. balzani Clade (B. aguilari, B. balzani, B. gladiator, B. melanopleura, B. palaestes), the redefined B. polytaenia Clade (B. botumirim, B. buriti, B. cipoensis, B. jaguariaivensis, B. leptolineata, B. polytaenia, B. stenocephala, and two undescribed species), the B. prasina Clade (B. bischoffi, B. caingua, B. cordobae, B. goiana, B. guentheri, B. marginata, B. phaeopleura, B. prasina, B. pulchella, and one undescribed species), the B. riojana Clade (B. callipleura, B. marianitae, B. riojana), and the B. semiguttata Clade (B. caipora, B. curupi, B. joaquini, B. poaju, B. semiguttata, B. stellae, and two undescribed species). The monophyly of the B. prasina + B. riojana Clades, and that of the B. polytaenia + B. semiguttata Clades are well-supported. The relationships among these two clades, the B. balzani Clade, B. ericae + B. freicanecae, and B. cambui (representing the deepest phylogenetic splits within the B. pulchella Group) are recovered with weak support. We discuss the phenotypic evidence supporting the monophyly of the B. pulchella Group, and the taxonomy of several species, identifying three new synonyms of Boana polytaenia, one new synonym of Boana goiana, and one new synonym of B. riojana.

A new tiny toad species of Amazophrynella (Anura: Bufonidae) from east of the Guiana Shield in Amazonia, Brazil

The combination of different approaches has successfully delimited new species within many Neotropical species complexes traditionally classified as a single nominal organism. Recent studies have shown that the Amazonian endemic genus Amazophrynella, currently composed of 12 small-sized species, could harbor several additional species. Based on morphology and molecular data, we describe a new species of Amazophrynella from east of the Guiana Shield, in Pará state, Brazil. The new species is characterized by having one of the biggest size of the genus (SVL of males 16.0–17.8 mm and females 22.9–24.4 mm), presence of a large palmar tubercle (occupying 2/4 of the palmar surface), 5.6–8.1% uncorrected p-distance from its sister clade (including A. teko, A. sp.1, and A. manaos) for the 16S mitochondrial gene, and 8.8% for the COI. The new species described here represents a newly discovered lineage. Of the 12 Amazophrynella species currently recognized, two were describe in the last century (A. bokermanni and A. minuta) and the remaining species were recently discovered and described (in the last six years), which underscores the degree to which species richness of Amazophrynella is underestimated.

Climatic breadth of calling behaviour in two widespread Neotropical frogs: Insights from humidity extremes

Climate change is severely altering precipitation regimes at local and global scales, yet the capacity of species to cope with these changes has been insufficiently examined. Amphibians are globally endangered and particularly sensitive to moisture conditions. For mating, most amphibian species rely on calling behaviour, which is a key weather-dependent trait. Using passive acoustics, we monitored the calling behaviour of two widespread Neotropical frogs in 12 populations located at the humidity extremes but thermal mean of the species distribution. Based on 2,554 hr of recordings over a breeding season, we found that both the aquatic species Pseudis paradoxa and the arboreal species Boana raniceps exhibited calling behaviour at a wide range of relative humidity. Calling humidity was significantly lower in conspecific populations subjected to drier conditions, while calling temperature did not differ between populations or species. Overall, no variation in climatic breadth was observed between large and small choruses, and calling behaviour was scarcely detected during the driest, hottest and coldest potential periods of breeding. Our results showed that calling humidity of the studied species varies according to the precipitation regime, suggesting that widespread Neotropical anurans may have the capacity to exhibit sexual displays in different climatic environments. Regardless of the underlying mechanism (plasticity or local adaptation), which should be determined by common garden experiments, a wide and population-specific climatic breadth of calling behaviour may assist species to deal with changing humidity conditions. To our knowledge, this is the first study to explore the response capacity of anurans to perform calling behaviour under contrasting precipitation regimes.

The Influence of Environmental Variation on the Genetic Structure of a Poison Frog Distributed Across Continuous Amazonian Rainforest

Biogeographic barriers such as rivers have been shown to shape spatial patterns of biodiversity in the Amazon basin, yet relatively little is known about the distribution of genetic variation across continuous rainforest. Here, we characterize the genetic structure of the brilliant-thighed poison frog (Allobates femoralis) across an 880-km-long transect along the Purus-Madeira interfluve south of the Amazon river, based on 64 individuals genotyped at 7609 single-nucleotide polymorphism (SNP) loci. A population tree and clustering analyses revealed 4 distinct genetic groups, one of which was strongly divergent. These genetic groups were concomitant with femoral spot coloration differences, which was intermediate within a zone of admixture between two of the groups. The location of these genetic groups did not consistently correspond to current ecological transitions between major forest types. A multimodel approach to quantify the relative influence of isolation-by-geographic distance (IBD) and isolation-by-environmental resistance (IBR) nevertheless revealed that, in addition to a strong signal of IBD, spatial genetic differentiation was explained by IBR primarily linked to dry season intensity (r2 = 8.4%) and canopy cover (r2 = 6.4%). We show significant phylogenetic divergence in the absence of obvious biogeographical barriers and that finer-scaled measures of genetic structure are associated with environmental variables also known to predict the density of A. femoralis.

Recent and Rapid Radiation of the Highly Endangered Harlequin Frogs (Atelopus) into Central America Inferred from Mitochondrial DNA Sequences

Populations of amphibians are experiencing severe declines worldwide. One group with the most catastrophic declines is the Neotropical genus Atelopus (Anura: Bufonidae). Many species of Atelopus have not been seen for decades and all eight Central American species are considered “Critically Endangered”, three of them very likely extinct. Nonetheless, the taxonomy, phylogeny, and biogeographic history of Central American Atelopus are still poorly known. In this study, the phylogenetic relationships among seven of the eight described species in Central America were inferred based on mitochondrial DNA sequences from 103 individuals, including decades-old museum samples and two likely extinct species, plus ten South American species. Among Central American samples, we discovered two candidate species that should be incorporated into conservation programs. Phylogenetic inference revealed a ladderized topology, placing species geographically furthest from South America more nested in the tree. Model-based ancestral area estimation supported either one or two colonization events from South America. Relaxed-clock analysis of divergence times indicated that Atelopus colonized Central America prior to 4 million years ago (Ma), supporting a slightly older than traditional date for the closure of the Isthmus. This study highlights the invaluable role of museum collections in documenting past biodiversity, and these results could guide future conservation efforts. An abstract in Spanish (Resumen) is available as supplementary material.

Gene flow creates a mirage of cryptic species in a Southeast Asian spotted stream frog complex

Most new cryptic species are described using conventional tree- and distance-based species delimitation methods (SDMs), which rely on phylogenetic arrangements and measures of genetic divergence. However, although numerous factors such as population structure and gene flow are known to confound phylogenetic inference and species delimitation, the influence of these processes is not frequently evaluated. Using large numbers of exons, introns, and ultraconserved elements obtained using the FrogCap sequence-capture protocol, we compared conventional SDMs with more robust genomic analyses that assess population structure and gene flow to characterize species boundaries in a Southeast Asian frog complex (Pulchrana picturata). Our results showed that gene flow and introgression can produce phylogenetic patterns and levels of divergence that resemble distinct species (up to 10% divergence in mitochondrial DNA). Hybrid populations were inferred as independent (singleton) clades that were highly divergent from adjacent populations (7%-10%) and unusually similar (<3%) to allopatric populations. Such anomalous patterns are not uncommon in Southeast Asian amphibians, which brings into question whether the high levels of cryptic diversity observed in other amphibian groups reflect distinct cryptic species-or, instead, highly admixed and structured metapopulation lineages. Our results also provide an alternative explanation to the conundrum of divergent (sometimes nonsister) sympatric lineages-a pattern that has been celebrated as indicative of true cryptic speciation. Based on these findings, we recommend that species delimitation of continuously distributed "cryptic" groups should not rely solely on conventional SDMs, but should necessarily examine population structure and gene flow to avoid taxonomic inflation.

Fifty years after: A taxonomic revision of the amphibian species from the Ecuadorian biodiversity hotspot Abra de Zamora, with description of two new Pristimantis species

Abra de Zamora is an important biodiversity hotspot in southern Ecuador. Between 1938 and 2010, eleven species of frogs were described from here: Lynchius flavomaculatus, Gastrotheca psychrophila, Pristimantis balionotus, P. colodactylus, P. cryptomelas, P. percultus, P. versicolor, P. vidua, Telmatobius cirrhacelis, P. andinognomus, and Atelopus podocarpus. Unfortunately, many of these species were not re-encountered after their original description, and for the majority DNA samples were not available, making their phylogenetic position unknown. In this study, we assess the current state of the amphibians from Abra de Zamora, by: i. redescribing the species which were first reported from the area, by contributing genetic delimitation (for L. flavomaculatus, P. balionotus, P. colodactylus, P. percultus, and P. vidua), release call (L. flavomaculatus) and advertisement call descriptions (for P. balionotus, P. vidua and P. versicolor); ii. presenting an updated amphibian species list of Abra de Zamora, with the description of two additional Pristimantis species; iii. updating the distribution of these species, including data collected in similar montane habitats from surrounding areas; and iv. amending recommendations regarding their conservation status.

Resolving a taxonomic and nomenclatural puzzle in mantellid frogs: synonymization of Gephyromantis azzurrae with G. corvus, and description of Gephyromantis kintana sp. nov. from the Isalo Massif, western Madagascar

The genus Gephyromantis belongs to the species-rich family Mantellidae and is currently divided in six subgenera. Among these is the subgenus Phylacomantis, which currently includes four described species: Gephyromantispseudoasper, G.corvus, G.azzurrae, and G.atsingy. The latter three species are distributed in western Madagascar, and two of them (G.azzurrae and G.corvus) occur in the Isalo Massif. Based on the analysis of molecular data (a fragment of the 16S rRNA gene), morphological inspection of museum specimens, and photographic comparisons, G.azzurrae is synonymised with G.corvus and the second Phylacomantis lineage of Isalo is described as G.kintanasp. nov. This medium-sized frog species (adult snout-vent length 35–44 mm) is assigned to this subgenus according to genetic and morphological similarities to the other known species of Phylacomantis. Gephyromantiskintanasp. nov. is known only from the Isalo Massif, while new records for G.corvus extend its range to ca. 200 km off its currently known distribution. These two taxa seem to occur in syntopy in at least one locality in Isalo, and the easiest way to distinguish them is the inspection of the ventral colouration, dark in G.corvus and dirty white in G.kintana.

A new stump-toed frog from the transitional forests of NW Madagascar (Anura, Microhylidae, Cophylinae, Stumpffia)

A new species of the miniaturised microhylid frog genus Stumpffia, from north-western Madagascar, is described. Stumpffiafroschauerisp. nov. differs from all other described Stumpffia species in colouration and morphology and is genetically divergent (≥ 7% uncorrected p-distance to all other nominal species of the genus) in a fragment of the mitochondrial 16S rRNA gene and in a segment of the nuclear Rag-1 gene. The new species is reliably known only from a few specimens collected in the Sahamalaza (and surroundings) region. Its known distribution is limited to three forest patches severely threatened by fire, drought and high levels of forest clearance, thus suggesting a classification of “Critically Endangered” according to IUCN Red List criteria.

Comparison of the mitochondrial phylogeographical structure of a generalist and two specialist frog species reveals contrasting patterns in the Eastern and Western Cape provinces of South Africa

In this study, we examined the phylogeographical structure of three frog species (Anhydrophryne rattrayi, Arthroleptis wageri and Cacosternum nanum) in the Eastern and Western Cape provinces of South Africa. The first two species are forest dwelling and exhibit direct development, whereas the last species is a habitat generalist, breeding in open freshwater bodies and exhibiting rapid metamorphosis. Evolutionary relationships were inferred using combined mitochondrial DNA (mtDNA) sequence data [16S rRNA and cytochrome b (Cytb)]. Divergence times were estimated for each species using the combined mtDNA dataset, and population genetic structuring was inferred using haplotype networks and analysis of molecular variance using the rapidly evolving Cytb locus. The two forest-dwelling species (Anhydrophryne rattrayi and Arthroleptis wageri) each revealed two statistically well-supported clades and were characterized by marked genetic differentiation and the general absence of shared maternal haplotypes, indicating no maternal gene flow between conspecific populations; a result corroborated by moderate values of pairwise genetic distance. In contrast, for the generalist species C. nanum, two shallow clades were observed and several haplotypes were shared between localities, indicating moderate maternal gene flow. Diversification in the two forest-dwelling species occurred during the Plio-Pleistocene climatic oscillations and was associated with increased xeric conditions, whereas in C. nanum a recent, Holocene divergence was inferred. Ancient climatic factors thought to be causal in the divergences within each of the three species are discussed. The marked mtDNA differentiation in the two forest specialist species suggests the presence of distinct management units that should be considered in future conservation management decisions.

DNA-based species delimitation reveals cryptic and incipient species in synchronous flashing fireflies (Coleoptera: Lampyridae) of Southeast Asia

Synchronous flashing fireflies of the genus Pteroptyx are ubiquitous throughout Southeast Asia, yet fundamental knowledge about their biodiversity is lacking. Recent studies have revealed notable population-level phylogeographical structure within the Pteroptyx tener and P. bearni groups in Malaysia, suggesting that cryptic species may exist. Additionally, morphological and genetic similarities between P. balingiana and P. malaccae have raised questions about the former’s validity as a distinct species. We collected samples from previously unsampled populations and assembled the most comprehensive genetic dataset for Pteroptyx to date, to characterize species boundaries within the P. tener, P. bearni and P. malaccae groups. Using a suite of species delimitation analyses, we show that P. tener along the west coast of Peninsular Malaysia (PM) is distinct from populations from the east coast and Borneo despite the absence of morphological differentiation. However, analyses could not conclusively differentiate P. bearni from Borneo and eastern PM, nor identify P. balingiana and P. malaccae as distinct species, indicating that these populations may be conspecific or represent incipient species. This study underlines the need to increase geographical, taxonomic and genetic sampling of Southeast Asian fireflies to provide a better understanding of their biodiversity.

Vastly underestimated species richness of Amazonian salamanders (Plethodontidae: Bolitoglossa) and implications about plethodontid diversification

We present data showing that the number of salamander species in Amazonia is vastly underestimated. We used DNA sequences of up to five genes (3 mitochondrial and 2 nuclear) of 366 specimens, 189 corresponding to 89 non-Amazonian nominal species and 177 Amazonian specimens, including types or topotypes, of eight of the nine recognized species in the region. By including representatives of all known species of Amazonian Bolitoglossa, except for one, and 73% of the currently 132 recognized species of the genus, our dataset represents the broadest sample of Bolitoglossa species, specimens, and geographic localities studied to date. We performed phylogenetic analyses using parsimony with tree-alignment and maximum likelihood (ML) with similarity alignment, with indels as binary characters. Our optimal topologies were used to delimit lineages that we assigned to nominal species and candidate new species following criteria that maximize the consilience of the current species taxonomy, monophyly, gaps in branch lengths, genetic distances, and geographic distribution. We contrasted the results of our species-delimitation protocol with those of Automated Barcode Gap Discovery (ABGD) and multi-rate Poisson Tree Processes (mPTP). Finally, we inferred the historical biogeography of South American salamanders by dating the trees and using dispersal-vicariance analysis (DIVA). Our results revealed a clade including almost all Amazonian salamanders, with a topology incompatible with just the currently recognized nine species. Following our species-delimitation criteria, we identified 44 putative species in Amazonia. Both ABGD and mPTP inferred more species than currently recognized, but their numbers (23-49) and limits vary. Our biogeographic analysis suggested a stepping-stone colonization of the Amazonian lowlands from Central America through the Chocó and the Andes, with several late dispersals from Amazonia back into the Andes. These biogeographic events are temporally concordant with an early land bridge between Central and South America (~10-15 MYA) and major landscape changes in Amazonia during the late Miocene and Pliocene, such as the drainage of the Pebas system, the establishment of the Amazon River, and the major orogeny of the northern Andes.

A new species of cryptic Bush frog (Anura, Rhacophoridae, Raorchestes) from northeastern Bangladesh

Raorchestes is a speciose genus of bush frogs with high diversity occurring in the Western Ghats of India. Relatively fewer species have been recorded across India, through Bangladesh, southern China, into Vietnam and Peninsular Malaysia. Many bush frogs are morphologically cryptic and therefore remain undescribed. Here, a new species, Raorchestes rezakhani sp. nov., is described from northeastern Bangladesh based on morphological characters, genetics, and bioacoustics. The 16S rRNA gene distinguished this species from 48 known species of this genus. Bayesian Inference and Maximum Likelihood analyses indicated that the new species was most similar to R. tuberohumerus, a species found in the Western Ghats, and to R. gryllus, a species found in Vietnam. Bioacoustics indicated that their calls were similar in pattern to most Raorchestes species, although number of pulses, duration of pulses, pulse intervals and amplitude differentiated it from a few other species. It is suggested that northeastern India, Bangladesh, northern Myanmar, and southern China represent important, relatively unexplored areas that could yield additional species of Raorchestes. Since many remaining habitat patches in Bangladesh are under severe threat from deforestation, efforts should be made to protect these last patches from further degradation.

A new species of Leptobrachella (Anura, Megophryidae) from Guizhou Province, China

This study describes a new species of the genus Leptobrachella, Leptobrachellasuiyangensissp. nov. from the Huoqiuba Nature Reserve, Suiyang County, Guizhou Province, China, based on morphological data and phylogenetic analyses (16S rRNA mtDNA). The new species can be distinguished from other congeners by the molecular divergence and by a combination of morphological characters, including body size, dorsal and ventral patterns, dorsal skin texture, size of the pectoral and femoral glands, degree of webbing and fringing on the toes and fingers, dorsum coloration, and iris coloration in life. Currently, the genus Leptobrachella contains 75 species, 21 of which are found in China, including seven species reported from Guizhou Province. The uncorrected sequence divergence percentage between Leptobrachellasuiyangensissp. nov. and all homologous DNA sequences available for the 16S rRNA gene was found to be >4.7%. The new record of the species and its relationships with others in the same genus imply that species distribution, habitat variation, environmental adaptation, and diversity of the genus Leptobrachella in southwest China need to be further investigated.

Systematics of the Boana semilineata species group (Anura: Hylidae), with a description of two new species from Amazonian Ecuador

The combination of genetic and phenotypic characters for species delimitation has allowed the discovery of many undescribed species of Neotropical amphibians. In this study, we used DNA sequences (genes 12S, 16S, ND1 and COI) and morphologic, bioacoustic and environmental characters of the Boana semilineata group to evaluate their phylogenetic relationships and assess their species limits. In addition, we included DNA sequences of several species of Boana to explore cryptic diversity in other groups. We found three Confirmed Candidate Species (CCS) within the B. semilineata group. Holotype examination of Hyla appendiculata shows that it is a valid species that corresponds to one of the CCS, which is here transferred to Boana. We describe the two remaining CCS. Our phylogeny highlights a number of secondary but meaningful observations that deserve further investigation: (1) populations of B. pellucens from northern Ecuador are more closely related to B. rufitela from Panama than to other Ecuadorian populations of B. pellucens; (2) we report, for the first time, the phylogenetic relationships of B. rubracyla showing that it is closely related to B. rufitela and B. pellucens; and (3) B. cinerascens and B. punctata form two species complexes consisting of several unnamed highly divergent lineages. Each of these lineages likely represents an undescribed species.

Four new species of Pristimantis Jiménez de la Espada, 1870 (Anura: Craugastoridae) in the eastern Amazon

The Pristimantis genus (Anura: Craugastoridae) is the most diverse among all vertebrates with 531 described species. The highest diversity occurs in Ecuador (215 species), followed by Colombia (202), Peru (139), Venezuela (60), Brazil (30), Bolivia (17), Guyana (6) Suriname and French Guiana (5). The genus is divided into 11 species groups. Of these, the P. conspicillatus group (containing 34 species), distributed in extreme southeastern Costa Rica, Isla Taboga (Panama), northern South America (from Colombia to eastern Guyana), south Bolivia, and is the best represented in Brazil (16 species). The main characteristics of this group are the tympanic membrane and tympanic annulus distinct (except in P. johannesdei); dorsum smooth or shagreen; dorsal lateral fold present or absent; usually smooth belly, but may be weakly granular in some species; toe V slightly larger than the toe III. Most of the taxonomic inconsistencies in species of Pristimantis could be due to its much conserved morphology and the lack of comprehensive taxonomic evaluations. Thus, an ongoing challenge for taxonomists dealing with the Pristimantis genus is the ubiquitous abundance of cryptic species. In this context, accurate species delimitation should integrate evidences of morphological, molecular, bioacoustics and ecological data, among others. Based on an integrative taxonomy perspective, we utilize morphological, molecular (mtDNA) and bioacoustic evidence to describe four new species of the Pristimantis conspicillatus group from the eastern Amazon basin. Pristimantis giorgiisp. nov. is known from the Xingu/Tocantins interfluve and can be distinguished from the other Pristimantis species of the region by presenting discoidal fold, dorsolateral fold absent, vocalization composed of three to four notes and genetic distance of 7.7% (16S) and 14.8% (COI) from P. latro, the sister and sympatric species with respect P. giorgiisp. nov.. Pristimantis pictussp. nov. is known to the northern Mato Grosso state, Brazil, and can be distinguished from the other species of Pristimantis by presenting the posterior surface of the thigh with light yellow patches on a brown background, also extending to the inguinal region, vocalization consisting of four to five notes and a genetic distance of 11.6% (16S) and 19.7% (COI) from P. pluviansp. nov., which occurs in sympatry. Pristimantis pluviansp. nov. is known to the northern Mato Grosso state, Brazil, and may be distinguished from the other Pristimantis species by having a posterior surface of the thigh reddish and vocalization composed of two notes. Pristimantis moasp. nov. is known to the northern Tocantins state and southwestern Maranhão state. This species can be distinguished from the other Pristimantis species by possessing slightly perceptible canthal stripe, external thigh surface with dark yellow spots on brown background, vocalization consisting of three to five notes and genetic distance of 2.3–11.7 (16S) and 10.5–23.1 (COI) for the new Pristimantis species of this study.