Frog Species Research Articles

A new genus and species of toad from Mount Kenya illuminates East African montane biogeography

Abstract Discoveries of new species can greatly impact our understanding of the biogeography of a region. For example, groups of amphibian lineages restricted to the Afrotemperate forests of Tanzania and Ethiopia are indicative of a shared biogeographical history of this highly discontinuous ecosystem. Curiously, many of these lineages are absent from the geographically intermediate Kenyan highlands. This phylogeographical interval is generally considered to be attributable to the younger, volcanic origins of much of the Kenyan highlands, and thus an amphibian fauna that is derived largely from recent colonization events rather than comprising older relicts. Contrasting with this view, here we report on the discovery of a single specimen of Bufonidae (true toad) from Mount Kenya. The specimen belongs to a species new to science and deserves recognition at the generic level owing to its notable molecular phylogenetic and morphological divergences from other described taxa. It is most closely related to the Tanzanian genera Churamiti and Nectophrynoides. The discovery of this new toad and its association with Afrotemperate species is significant because it links Kenya to the biogeographically more ancient Tanzanian mountains and supports the potential longevity of the Afrotemperate forests in Kenya. Broadly, it highlights that we are still adding major branches to the phylogeny of anurans.

Host ecology drives frog skin microbiome diversity across ecotone in South-Central North America

Anurans (frogs and toads) are an ecologically diverse group of vertebrate organisms that display a myriad of reproductive modes and life history traits. To persist in such an expansive array of habitats, these organisms have evolved specialized skin that is used for respiration while also protecting against moisture loss, pathogens, and environmental contaminants. Anuran skin is also colonized by communities of symbiotic microorganisms, and these skin microbiota serve critical roles in numerous processes associated with anuran host health and persistence such as pathogen resistance and immunity. However, gaps remain in our understanding of the environmental and evolutionary processes that shape frog skin microbial communities. Here, we combined existing anuran disease data with 16S rRNA skin microbial inventories to elucidate the roles that geographic location, host evolutionary history, host ecology, and pathogen presence play in the microbial community assemblage of five co-distributed frog host species in Oklahoma. These focal species possess distinct ecological preferences: aquatic, semi-aquatic, and arboreal, and our results indicate that host ecology is the primary driver of frog skin microbial community structure. Additionally, compositional differences were observed among select host species based on geographic location, but this was not consistent among all five frog species. We did not find evidence of phylogenetic signal among our samples and results from the Classification and Regression Tree Analysis revealed that the presence of the amphibian pathogen Batrachochytrium dendrobatidis and the severity of infection were not drivers of skin microbiome differences among our focal host species. Results from this comparative study contribute to our growing understanding of the environmental and host-associated drivers of skin microbial community assemblage and represents one of the first studies on landscape-level variation in skin microbial communities among North American frogs.

A dataset for benchmarking Neotropical anuran calls identification in passive acoustic monitoring

Global change is predicted to induce shifts in anuran acoustic behavior, which can be studied through passive acoustic monitoring (PAM). Understanding changes in calling behavior requires automatic identification of anuran species, which is challenging due to the particular characteristics of neotropical soundscapes. In this paper, we introduce a large-scale multi-species dataset of anuran amphibians calls recorded by PAM, that comprises 27 hours of expert annotations for 42 different species from two Brazilian biomes. We provide open access to the dataset, including the raw recordings, experimental setup code, and a benchmark with a baseline model of the fine-grained categorization problem. Additionally, we highlight the challenges of the dataset to encourage machine learning researchers to solve the problem of anuran call identification towards conservation policy. All our experiments and resources have been made available at https://soundclim.github.io/anuraweb/.

The radiation continuum and the evolution of frog diversity

Most of life’s vast diversity of species and phenotypes is often attributed to adaptive radiation. Yet its contribution to species and phenotypic diversity of a major group has not been examined. Two key questions remain unresolved. First, what proportion of clades show macroevolutionary dynamics similar to adaptive radiations? Second, what proportion of overall species richness and phenotypic diversity do these adaptive-radiation-like clades contain? We address these questions with phylogenetic and morphological data for 1226 frog species across 43 families (which represent >99% of all species). Less than half of frog families resembled adaptive radiations (with rapid diversification and morphological evolution). Yet, these adaptive-radiation-like clades encompassed ~75% of both morphological and species diversity, despite rapid rates in other clades (e.g., non-adaptive radiations). Overall, we support the importance of adaptive-radiation-like evolution for explaining diversity patterns and provide a framework for characterizing macroevolutionary dynamics and diversity patterns in other groups.

Hidden shifts in allometry scaling between sound production and perception in anurans.

Animal communication consists of signal production and perception, which are crucial for social interactions. The main form used by anurans is auditory communication, in most cases produced as advertisement calls. Furthermore, sound perception happens mainly through an external tympanic membrane, and plays an important role in social behavior. In this study, we evaluated the influence of body and tympanic membrane sizes on call frequency across the phylogeny of anurans. We use data on snout-vent length, tympanic membrane diameter, and dominant frequency of the advertisement call from the literature and from natural history museum collections. We mapped these traits across the anuran phylogeny and tested different models of diversification. Our final dataset includes data on body size, tympanic membrane size, and call dominant frequency of 735 anuran species. The best explanatory model includes body and tympanum size with no interaction term. Although our results show that call frequency is strongly constrained by body and tympanum size, we identify five evolutionary shifts in allometry from that ancestral constraint. We relate these evolutionary shifts to the background noise experienced by populations. Body size is important for myriad ecological interactions and tympanum size is strongly associated with female call frequency preferences. Thus, allometric escape in frog calls might arise through environmental selection such as breeding in fast flowing or soundscape competition, as well as sexual selection linked to tympanum size.

Linking species distribution models with structured expert elicitation for predicting management effectiveness

AbstractEffective biodiversity conservation requires robust and transparent prioritization of management actions. However, this is often hampered by a lack of spatially‐explicit data on habitat variables and empirical data on the effect of management actions. Although approaches exist that integrate structured expert elicitation (SEE) with species distribution models (SDMs) to encode species responses across habitat gradients, difficulties remain in predicting management outcomes under different settings, at a region‐wide scale when key habitat covariates are not spatially explicit. Therefore, we developed an approach to integrate SDMs with SEE to capture expert understanding of likely outcomes of management actions for individual frog species, and use this to spatially predict the effect of management actions. We demonstrate our approach across approximately 4000 wetlands in greater Melbourne, Victoria, Australia. As a measure of management effectiveness, we used the change in predicted probability of occurrence of seven frog species at wetlands 10 years after conservation actions are implemented (or not implemented). Management effect was elicited from experts under six scenarios. Individual expert estimates were aggregated using generalized linear models that were then used to spatially predict expected management effects, and a measure of uncertainty in the prediction, at all wetlands. Predicted management effect was strongly influenced by species initial probability of occurrence, with enhancing aquatic and surrounding vegetation an effective action for most species. We discuss practical challenges and recommend solutions in the integration of SDMs and SEE for the spatial prediction of management effect.

Morphology and Karyotype of Two Frog Species from Irian Jaya

This research aims to identify and compare the morphology and karyotype of Litoria caerulea and Litoria infrafrenata, which are useful as study materials to understand their patterns of relatedness and taxonomy. The results of this study indicate that the qualitative morphological characteristics of both frog species are different. Litoria caerulea has a chubby and short body with a distinctive feature of skin folds above the eyes that extend to the tympanum area, while Litoria infrafrenata has a slim and long body with a distinctive feature of a white line on the lower lip and along the front and hind limbs. And it was observed that the morphometry between the two frog species are significantly different (P ≤ 0.05).

Integrative species delimitation uncovers hidden diversity within the Pithecopus hypochondrialis species complex (Hylidae, Phyllomedusinae) and its phylogeography reveals Plio-Pleistocene connectivity among Neotropical savannas

Despite their limited vagility and pronounced habitat heterogeneity in the tropics, many anuran species have unexpectedly extensive geographic ranges. One prominent example of this phenomenon is Pithecopus hypochondrialis, which is found in the Cerrado, Guianan savanna, and Llanos domains, as well as isolated tracts of savanna and open habitat within the Amazon Forest. The present study employs an integrative species delimitation approach to test the hypothesis that P. hypochondrialis is in fact a species complex. We also reconstruct the relationships among the lineages delimited here and other Pithecopus species. In this study, we employ Ecological Niche Modelling (ENM) and spatiotemporal phylogeographic reconstruction approaches to evaluate a multitude of scenarios of connectivity across the Neotropical savannas. We identified three divergent lineages, two of which have been described previously. The lineages were allocated to a lowland Pithecopus clade, although the relationships among these lineages are weakly supported. Both the ENM and the phylogeographic reconstruction highlight the occurrence of periods of connectivity among the Neotropical savannas over the course of the Pliocene and Pleistocene epochs. These processes extended from eastern Amazonia to the northern coast of Brazil. The findings of the present study highlight the presence of hidden diversity within P. hypochondrialis, and reinforce the need for a comprehensive taxonomic review. These findings also indicate intricate and highly dynamic patterns of connectivity across the Neotropical savannas that date back to the Pliocene.

Monitoring the Green and Golden Bell Frog Litoria aurea on the Crookhaven floodplain at Nowra, New South Wales from 2016-2022 and implications for conservation

ABSTRACT Systematic (time constrained) and targeted surveys were conducted for the Green and Golden Bell Frog Litoria aurea from 2016-2022 on the Crookhaven River - Shoalhaven River floodplains, on the south coast of New South Wales. Systematic nocturnal surveys were conducted at 30-34 sites, three to four times between October and March. Litoria aurea were observed at 20 sites and males were heard calling at five of these. The majority of detections during the breeding season (January - February) were in flooded areas of Terara Swamp and Brundee Swamp, while outside the breeding season more frogs were seen in the catchment of Rotten Creek, the largest tributary of Brundee Swamp. Ten of the systematic sites were ponds constructed for the species as offsets for various developments. Breeding activity (calling males) was detected at two of these offset ponds, but no tadpoles or juveniles were found. The number of frogs detected during systematic surveys varied from eight to forty-four per season, while the number found during diurnal surveys of 136-175 sites annually ranged from zero to thirty-three. Although recruitment occurred in most years the population did not recover to that previously found in 2010-2012. The lack of recovery was influenced by drought, wildfire and a continual loss of habitat from urban developments. Large adult females were seen each survey beside Rotten Creek or nearby ponds suggesting the adult population overwinters within the catchment of this creek and disperse down this catchment to Brundee Swamp to breed in spring. The results from six years monitoring indicate the Crookhaven L. aurea population has not recovered in abundance and distribution since 2010-2012. The three most abundant species of frog Litoria fallax, Litoria peroni and Limnodynastes peroni were also analysed for site preference and population variations over the survey.

Distinguishing fanged frogs (Limnonectes) species (Amphibia: Anura: Dicroglossidae), from Thailand using high resolution melting analysis

Morphologically, species of fanged frogs (Limnonectes) are exceedingly similar, making it difficult to distinguish them within the complex. In Thailand, it has been difficult to distinguish between the sympatric species L. bannaensis and L. taylori, particularly among tadpoles, adolescents, and adult females. A precise identification contributes to a greater understanding of biodiversity, particularly for assessing distributions and population dynamics. Therefore, a novel approach is required. The objective of this study was to develop a high resolution melting analysis (HRM) for the rapid and accurate identification of six species of Limnonectes of the L. kuhlii complex found in Thailand, particularly the two sympatric fanged frogs. Here, HRM assays using 16S rRNA mitochondrial primers were designed and developed. There was as much as a 25.3% variation in the nucleotide sequence of the fragment amplified by HRM16S primers among the six species of Limnonectes. Prior to conducting an in vitro HRM, the DNA sequences were used in a simulation HRM, uMELT Quartz, to predict the melting curve for each species of Limnonectes. There were discrepancies between the predicted melting curves of each species generated by the programme. Consequently, in vitro HRM tests were conducted. The obtained melting curve and Tm values were consistent with those predicted, albeit with a slightly different Tm value and a more distinct melting curve. All evaluated species of Limnonectes could be easily distinguished from one another by comparing the melting curve shapes. The HRM assay was then used to confirm the species of 18 Limnonectes samples in comparison to the reference samples (confidence interval > 90%). In addition, the results of HRM were consistent with those of experts who used morphological analysis to identify species. The HRM was found to be useful, and therefore the method would also contribute to future ecological and systematic studies on the target species.

Global shortfalls of knowledge on anuran tadpoles

Despite the amount of data on different aspects of biodiversity, such as species distributions, taxonomy, or phylogenetics, there are still significant gaps and biases in the available information. This is particularly true for life history traits, with fragmentary data for most taxa, especially those with complex life cycles. Anurans (frogs and toads) show larval (premetamorphic) stages that are in general radically decoupled from adult forms in most biological aspects. Our understanding of this group is highly uneven, as the main wide-scope investigations focus on adult specimens and larval stages remain unknown for a significant part of the anuran tree. The main purpose of this work was to estimate the extent of knowledge gaps regarding the diversity of tadpoles, interpret their biological and geographical patterns, and discuss possible explanations and implications for other large-scale analyses. Our findings show that more than half of the anuran species described to date still lack information on their embryonic/larval stages. Furthermore, knowledge varies among taxonomic groups, larval ecomorphological guilds, and world ecoregions. Description percentages generally decrease in lineages with a higher proportion of species known or suspected to have endotrophic development. Also, geographic areas with the highest levels of ignorance in larval biology (Tropical Andes and New Guinea) coincide with the highest diversity of endotrophic guilds. Among exotrophic larvae, generalized lentic-lotic tadpoles have the widest distribution and levels of knowledge, whereas specialized lotic, fossorial, and terrestrial forms are more taxonomically and geographically restricted. Further large-scale analyses on tadpole biology are crucial for their impact in varied scientific disciplines including anuran conservation. At a conceptual level, the discussion of the anuran biphasic life cycle is pertinent in the context of shortfalls of biodiversity knowledge and their interrelationships.

Emergence of Elizabethkingia miricola in the Brazilian Amazon region

Infectious diseases are not only a threat to humans and animals but also to an entire ecosystem if the three axis of One Health are considered. Elizabethkingia miricola is a water-borne and opportunistic pathogen frequently evolving to high morbidity and mortality outcomes. More recently, reports on E. miricola infections causing death in different anuran species are increasing. Here, we reported the emergence, in a clinical setting in Brazil (Amazon region), of an E. miricola (EM15) with an almost untreatable antibiotic resistance phenotype that was closely related to the lineage involved with anuran infections worldwide. A genomic reconstruction revealed that EM15 belonged to a cluster represented by genomes from human and animal (anurans) sources recovered from China, Europe, and the Americas from 2002 to 2021, and from the Space Station Mir condensation water. Their resistome and virulome were also in agreement with their genetic relationship since they harboured the same set of resistance and putative virulence genes. Therefore, the emergence of EM15 in a clinical setting in the Amazon region, a hotspot area of anuran diversity and home to Amerindian groups that live in close relationship with the wildlife, may represent a warning to the public and environmental health.

Segregation in diet composition of two syntopic tree frog species, Hyla simplex and Polypedates megacephalus, in Ben En National Park, Vietnam

Abstract The segregation in one trophic niche of n-dimensional niches can allow many species to coexist in the same habitat. In this study, we conducted surveys in Ben En National Park, Thanh Hoa Province, Vietnam to examine stomach contents of two syntopic tree frog species, Hyla simplex and Polypedates megacephalus, using the stomach-flushing method. A total of 21 individuals of H. simplex and 32 individuals of P. megacephalus were sampled revealing 352 food items (H. simplex: 131 invertebrates belonging to 20 prey types of seven orders; P. megacephalus: 215 invertebrates belonging to 22 prey types of 11 orders). Generally, both species consumed slightly diverse and equal prey types. However, ants (Formicidae) and termites (Rhinotermitidae) were identified as the most dominant and important prey for the two tree frog species. With only 38.95% overlap, it is evident that there is tropic segregation between the two syntopic species.

Anomalies in three species of anurans in the state of Chiapas, Mexico

Anomalies in three species of anurans in the state of Chiapas, Mexico

Discovery of a new species of dwarf frog (Anura: Ceratobatrachidae: Alcalus) extends the northwestern distributional limits of the genus to Northeast India

We describe a new species of the genus Alcalus from the northeast Indian state of Arunachal Pradesh based on molecular, morphological, and osteological characters. The new species differs from its congeners based on a combination of morphological characters including snout-vent length (27–28 mm in males; 29.9–36.2 mm in females), disc on fingers and toes with horizontal/transverse groove on the dorsal surface, dorsal skin wrinkled, and a pair of faint dorsolateral stripes on back. The new species also differs from its congeners by a DNA sequence divergence of 7.6–25.4% in the mitochondrial gene fragment 12S–tVal–16S rRNA (1533 base pairs). We include a detailed osteological description of the new species and compare it with the type of this genus. This is the first record of this genus from India, which was recently also reported from Myanmar and Western China. Discovery of a new species from northeast India indicates the need for a systematic study to uncover the hidden diversity of the Indo-Burma biodiversity hotspot. http://zoobank.org/urn:lsid:zoobank.org:pub:FB75F850-2AD9-4643-97CE-7F3F1D58E3F8 http://zoobank.org/urn:lsid:zoobank.org:act:6104F7A5-7E5E-42A7-90A1-810C394CFB3E

Trophic ecology of juvenile amphibians: relative level of myrmecophagy in two anuran species

ABSTRACT Research on trophic niche dimensions is essential to understanding the role of species in ecosystems. In the case of amphibian conservation, it is particularly important to study juveniles, given the vulnerability of this life stage. Here, the diets consumed by juvenile Rhinella arenarum and Odontophrynus sp. were evaluated, with special attention paid to the incidence of ants. Diet composition was quantified by analyzing the amphibians’ stomach contents. The representation of different taxonomic prey groups was determined, and the relationships between the amphibians’ morphological traits and the characteristics of their prey were explored. Diet composition and diversity differed between juveniles of the two species. Juvenile R. arenarum occupied an intermediate position along the specialist-generalist spectrum. Their most commonly consumed prey were ants (mainly Solenopsis and Linepithema) followed by mites. Juvenile Odontophrynus sp. had a more generalist diet. Their most commonly consumed prey were Isopoda followed by Coleoptera and miscellaneous larvae. Snout-vent length (SVL) was greater for juvenile Odontophrynus sp. than for juvenile R. arenarum, but the latter consumed more prey. The results suggest that juveniles of R. arenarum tend to specialize more on ants than do juveniles of Odontophrynus sp.

Alkaloid-based chemical defenses and diet in six species of Australian poison frogs in the genus Pseudophryne (Myobatrachidae)

Alkaloid-based chemical defenses and diet in six species of Australian poison frogs in the genus Pseudophryne (Myobatrachidae)

Mortality and toxicity of a commercial formulation of cypermethrin in Physalaemus gracilis tadpoles

This study evaluated the lethal, sublethal, and toxic of a commercial formulation of cypermethrin in the anuran species Physalaemus gracilis. In the acute test, concentrations of 100–800 μg L−1 were tested over 96 h. In the chronic test, cypermethrin concentrations recorded in nature (1, 3, 6, and 20 μg L−1) were tested for mortality and then used for the micronucleus test and erythrocyte nuclear abnormalities over a 7-days period. The LC50 determined for P. gracilis for the commercial cypermethrin formulation was 273.41 μg L−1. In the chronic test, a mortality of more than 50% was observed at the highest concentration (20 μg L−1), as it caused half of the tadpoles studied to die. The micronucleus test showed significant results at concentrations of 6 and 20 μg L−1 and recorded the presence of several nuclear abnormalities, indicating the genotoxic potential of the commercial cypermethrin formulation for P. gracilis. Cypermethrin presented a high risk to the species, indicating that it has the potential to cause several problems in the short and long term and to affect the dynamics of this ecosystem. Therefore, it can be concluded that the commercial formulation of cypermethrin had toxicological effects on P. gracilis.

Heavy metal pollution alters reproductive performance and mate choice in an anuran, Strauchbufo raddei

Understanding the effects of pollution on reproductive performance and sexual selection is crucial for the conservation of biodiversity in an increasingly polluted world. The present study focused on the effect of environmental heavy metal pollution on sexually selected traits, including morphological characteristics and acoustic parameters, as well as mate choice in Strauchbufo raddei, an anuran species widely distributed in Northern China. The results showed that male courtship signals, including forelimb length, forelimb force, and advertisement calls, have evolved under the pressure of heavy metal pollution in young S. raddei. In addition, the breeding age was lower in the polluted areas, and younger individuals had more mating opportunities. However, males with heightened reproductive performance did not show the expected higher individual quality. The current study suggests that exposure to heavy metal pollution can induce stress in males, altering reproductive performance and further disrupting mate choice.

DISCOVERY OF THE RICHEST FROG FAUNA IN THE WORLD—AN EXPLORATION OF THE FORESTS TO THE NORTH OF LETICIA

Vouchers of 97 species of frogs and toads were obtained in a small section of primary rainforest and flooded forest approximately 10 kms north of Leticia in early 2003. In addition to the 97 species captured, there is good reason to suspect that the actual local fauna consists of no fewer than 123 species of frogs and toads. This local fauna is much larger than previous reports for the western part of the Amazon Basin but probably its size reflects the new methodologies employed rather than a biological “hotspot.”