Lead author Kazuko Hase of Kyoto University collected Bufo formosus tadpoles from four egg masses collected around the University of Tokyo’s Botanical Gardens and treated each egg mass as a sibling group. After hatching, the tadpoles were assigned to rearing conditions that combined tap water or pond water with either group rearing alongside 20 siblings or solitary rearing. Following two weeks, the researchers tested whether the tadpoles preferred associating with siblings or with nonsiblings.

Each choice test placed sibling, nonsibling and neutral zones in an experimental tank. Investigators tracked the movement of focal tadpoles for 60 minutes and compared the time each animal spent in the three zones. The tracked sample comprised 47 group-reared and 43 solitary-reared tadpoles. The analysis found that tadpoles did not prefer siblings under either rearing condition, indicating a lack of the sibling association preference reported in some other tadpole species. The findings also showed that solitary-reared animals generally had a reduced tendency to approach others, whether they were siblings or nonsiblings.

Solitary-reared tadpoles spent a significantly greater proportion of their time in the neutral zone than group-reared tadpoles, a difference reported with t = 3.155 and p = 0.002. This response was observed across the tested aquatic environments, supporting the authors’ conclusion that social isolation had a robust influence on association behavior. In contrast, the researchers detected no significant effect of tap water versus pond water on the tadpoles’ choices.

“Unlike closely related species in which kin recognition has been confirmed during social aggregation, I was surprised to find that it is not essential for social aggregation in the Japanese common toad,” said Hase, the study’s corresponding author. The experiment therefore does not demonstrate that Japanese common toad tadpoles lack all social responses: they continued to aggregate, but their choices did not reveal a significant preference for kin. It instead indicates that their association behavior is more strongly associated with prior experience of living with peers than with sibling status or water source.

The study was conducted in laboratory tanks and used one species of amphibian larva, so its conclusions are limited to the tested populations, rearing conditions and observation period. The experiment did not establish how long solitary-rearing effects persist or whether they occur in natural ponds. Nevertheless, the findings offer a mechanistic explanation for sociality that does not require kin recognition: repeated social contact during early development may help establish the tendency to approach other members of the species.

Japanese common toad tadpoles aggregate as a response to predation risk, making their social decisions relevant to both behavioral ecology and conservation. Hase noted that the Japanese common toad faces a threat of extinction and said the research may help inform efforts to protect the species. The article, “Social isolation, rather than kinship, influences association behavior in toad tadpoles (Bufo formosus),” appeared in Animal Cognition on 6 August 2026. The authors declared no competing interests.

Subject of Research: Experimental study of how social isolation, kinship and water environment affect association behavior in Japanese common toad tadpoles.

Article Title: The tadpoles that don't care about their siblings

Article References: The tadpoles that don't care about their siblings. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: Japanese common toad, tadpole behavior, social isolation, kin recognition, association behavior, social aggregation, Bufo formosus, early-life experience, Animal Cognition, amphibian conservation, tadpoles, don't

The project centered on the European green toad, Bufotes viridis, a pioneer species associated with temporary, often vegetation-free pools and a species categorized as Vulnerable in Austria. The researchers provided 300 standardized polyethylene mini-ponds to citizen scientists across Austria and installed two additional ponds at the Vienna Zoo. Of the 300 distributed to volunteers, 289 were confirmed by photographs to have been set up and were included in the monitoring results.

Each mini-pond measured 120 by 90 by 40 cm, held 150 litres of water and had a surface area of 0.98 m². The team selected the commercially available model with the largest surface-to-volume ratio that met their requirements. Ribbed sides and an attachable coconut-fiber mesh were intended to help animals leave the ponds. Participants were asked not to add soil, gravel, sand, stones, plants or wood, thereby maintaining broadly comparable early-successional, oligotrophic conditions, and to replenish the water regularly.

Pond placement prioritized the known post-2000 distribution of the European green toad in Austria. The researchers used the Austrian Herpetofauna Database, unpublished observations and records from iNaturalist to identify areas, including places associated with populations considered lost, such as Carinthia. Applicants were asked about existing garden ponds and whether amphibians had been observed on their properties, and satellite imagery was used to assess barriers and nearby water bodies. Most ponds were installed and filled during the first week of March 2024.

Monitoring was conducted through the custom AmphiApp smartphone application, which transferred observations to a web-integrated database. Citizen scientists were asked to inspect their ponds every second weekend from 2 March through 1 September 2024 and to report additional observations outside the schedule. Records included the date and time, geographic coordinates, relative water level, whether water had been added, a tentative identification, a description, a photograph and, optionally, an audio recording. The team validated the records and generally treated an observation as associated with a mini-pond when the animal was recorded within five metres, although such cases were rare.

Pelophylax species, which could not be distinguished reliably from photographs or recordings and were therefore treated as one taxon, generated 107 records from 47 ponds and represented 42.3% of all reports. The European green toad produced 59 records from 17 ponds, while the common toad, Bufo bufo, produced 17 records from 14. The smooth newt, Lissotriton vulgaris, was recorded in 12 ponds and the agile frog, Rana dalmatina, in 13. Other observations included the common frog, yellow-bellied toad, fire-bellied toad, European tree frog, alpine newt and crested newt. Reports generally increased during the expected aquatic season, with most made from May through September.

Signs of reproduction—including amplexus, eggs, larvae or metamorphs—were recorded in 29 of the 289 ponds. Evidence of reproduction was reported for eight identified taxa: the smooth newt in six of the 12 ponds where the species was recorded; Pelophylax species in five of 47; the European green toad in three of 17; the common toad in two of 14; the yellow-bellied toad in two of five; and one each for the European tree frog, common frog and alpine newt. The researchers could not confirm reproduction for the agile frog, fire-bellied toad or crested newt. An additional 19 ponds contained reproductive signs that could only be classified as Anura.

To account for the likelihood that amphibians present in a pond went unobserved, the researchers fitted Bayesian single-species occupancy models with the spOccupancy R package. Records were organized into 14 two-week intervals, and only observations within each taxon’s typical reproductive activity period were used. Models were fitted for the smooth newt, European green toad, yellow-bellied toad and Pelophylax species, the four taxa detected in at least 10 intervals. Per-interval detection probabilities were estimated at 0.107, with a 95% Bayesian credible interval of 0.052–0.176, for the European green toad and 0.154, with an interval of 0.062–0.274, for the yellow-bellied toad. Cumulative probabilities over the respective activity periods ranged from 0.658 for the European green toad to 0.836 for the smooth newt. The models found no significant differences among the four species.

These findings provide first-season evidence that small, newly created ponds can attract amphibians and support reproductive activity, but they do not establish the ponds’ long-term effectiveness. The study covered one active season, used fortnightly observations by mostly untrained citizen scientists and could model only four taxa because other species had too few detections across enough intervals. Most volunteers sampled during daylight, which likely reduced detection of nocturnal species, while brief aquatic residency also limited detection of explosive breeders. The authors anticipate that additional species and amphibians may use the ponds during a second season, but that possibility remains a forecast rather than a measured result.

Subject of Research: First-season amphibian colonization and reproduction in Austrian garden mini-ponds monitored through citizen science

Article Title: Early amphibian colonizers of man-made mini-ponds: first results of a citizen science experiment

Article References: Siebert, J., Burgstaller, S., Kornilev, Y. V., Krall, M. M., Hamernik, D., Kremser, J., Loupal, A., Spießberger, M., Zaller, J. G., Schweiger, S., Graf, W., Dörler, D., Heigl, F., & Landler, L. (2025). Early amphibian colonizers of man-made mini-ponds: first results of a citizen science experiment. Herpetozoa, 38, 231-240. https://doi.org/10.3897/herpetozoa.38.e153679

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.38.e153679

Keywords: amphibian conservation, citizen science, garden ponds, European green toad, breeding habitats, occupancy modelling, detection probability, Austria, habitat creation, Early, amphibian, colonizers

Six additional samples came from tail fins of tadpoles observed at the reserve; the tadpoles themselves were not collected. The five adults had snout–vent lengths of 27.6–28.7 mm. Preserved specimens were deposited at the Guangdong Polytechnic of Environmental Protection Engineering, the Museum of Biology at Sun Yat-sen University and the Herpetological Museum at the Chengdu Institute of Biology.

Researchers combined external measurements and examination of diagnostic features with phylogenetic analysis of partial mitochondrial 16S ribosomal RNA and cytochrome c oxidase 1 sequences. Maximum-likelihood and Bayesian analyses produced essentially identical tree topologies, while genetic distances were calculated from 16S data using an uncorrected p-distance model. The five adults formed a monophyletic lineage with a maximum-likelihood bootstrap value of 100 and a Bayesian posterior probability of 1.00.

This lineage was the sister group to B. acuta , with strong support of 97 and 1.00, respectively, and differed from it by a mean 16S p-distance of 6.5%. Morphological examination also distinguished the specimens from all recognized congeners, supporting their description as B. yangchunensis . Among the new species’ closest relatives, B. yangchunensis differs from B. acuta in having heels that just meet when the hindlimbs are folded, no vomerine ridge, and toes without webbing or lateral fringes.

Breeding males have nuptial pads bearing dense nuptial spines on the dorsal bases of the first two fingers, whereas B. acuta has weak pads without spines. Compared with B. gaolanensis , the new species has meeting rather than non-meeting heels, a sharpened rather than rounded snout in dorsal view, and visible nuptial pads and spines. B. yangchunensis is currently known only from Ehuangzhang Provincial Nature Reserve, where it inhabits flowing montane streams and nearby forest floor and leaf litter.

The surrounding habitat consists of evergreen broad-leaved forest mixed with bamboo groves at elevations of 900–1,100 metres. Male advertisement calls were heard from February to May, and calling males were observed on leaves 10–30 cm above the ground. These observations document the known locality and activity period but do not establish the species’ full distribution or population size.

Field and molecular evidence also extended the known distributions of B. acuta and B. yunkaiensis to Ehuangzhang. Tail-fin samples assigned to B. acuta clustered with reference specimens from Heishiding Nature Reserve and Mount Yunkai, while samples assigned to B. yunkaiensis clustered with Mount Yunkai reference samples. The new B. acuta locality is about 188 km in straight-line distance from its type locality, and the B. yunkaiensis locality is about 52 km from Mount Yunkai.

Using the IUCN Red List categories and criteria and the GeoCAT platform, the researchers recommended listing B. acuta as Endangered under criteria B1ab(iii) and B2ab(iii). Its extent of occurrence was estimated at 3,170 km² and its area of occupancy at 12 km², with records from three independent locations and an observed decline in habitat quality. The authors characterized this as a non-genuine downlisting from Critically Endangered because the new populations showed that its range had been underestimated.

It was a recommendation for reassessment rather than a final Red List decision. The authors recommended Critically Endangered status for B. yangchunensis , B. yunkaiensis and B. gaolanensis under specified geographic-range criteria. The new species was known from one location, with an area of occupancy of 4 km²; B. yunkaiensis was known from two locations and had an area of occupancy of 8 km²; and B. gaolanensis also had an area of occupancy of 8 km².

These recommendations could change if additional populations were found in adjacent potentially suitable habitat, but such occurrence was not established by the study.

Subject of Research: Taxonomic description and extinction-risk assessment of Chinese horned toads in western Guangdong

Article Title: A new species of Chinese horned toad ( Anura , Megophryidae , Boulenophrys ) from western Guangdong Province, China, with recommendations for extinction risk assessments for several related congeners

Article References: Zhao, Y.-Y., Lin, S.-S., Li, Y.-H., Lyu, Z.-T., Zheng, K., Zeng, Z.-C., Borzée, A., & Wang, J. (2025). A new species of Chinese horned toad (Anura, Megophryidae, Boulenophrys) from western Guangdong Province, China, with recommendations for extinction risk assessments for several related congeners. Herpetozoa, 38, 345-357. https://doi.org/10.3897/herpetozoa.38.e171400

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.38.e171400

Keywords: Boulenophrys, new species, Chinese horned toad, Guangdong, field survey, molecular phylogenetics, range extension, IUCN Red List, extinction risk, amphibian conservation, species, Chinese

The Karpathos water frog is no ordinary frog. Until recently, it was considered endemic to Karpathos alone and was classified as critically endangered by the IUCN. A phylogenetic study later revealed that frog populations on the nearby island of Rhodes belong to the same species, prompting a reassessment that downgraded its status to endangered. That relative reprieve, however, masks a precarious reality. The Karpathos populations are sparse, the island’s freshwater bodies are few and in poor condition, and devastating wildfires that swept across Rhodes in July 2023 may have further damaged frog habitat. Adult Karpathos frogs are small animals, usually measuring between five and seven centimeters from snout to vent, and they remain diurnal throughout the year, feeding opportunistically on beetles, spiders, isopods, and wasps. Every individual lost to predation matters for a population already squeezed by shrinking water sources.

The freshwater crab Potamon karpathos, by contrast, is a native and apparently thriving member of the island’s ecosystem. The genus Potamon includes 22 species distributed across Asia, Southern Europe, and Northern Africa, and seven of these species inhabit the Aegean Islands, with P. karpathos being the sole representative on Karpathos. The feeding ecology of this particular crab remains largely understudied, but research on related Potamon species points to an opportunistic, omnivorous diet with a general preference for plant material. That dietary flexibility can extend to surprising extremes, including documented cases of snake-eating, or ophiophagy, in other members of the genus. The new observations from Karpathos suggest that frogs, too, fall within the crab’s predatory repertoire when circumstances bring the two animals into close quarters.

Invertebrate predation on amphibians is a well-documented phenomenon across much of the world, with insects and arachnids serving as the most frequent attackers. Marine and freshwater crabs of the infraorder Brachyura have also been recorded preying on frogs in other parts of the globe, including reports from South America. What makes the Karpathos discovery remarkable is its geographic novelty: despite centuries of natural history study in Europe, no crustacean had ever been formally documented consuming an amphibian on the continent. The finding also fills in a gap in understanding the ecological relationships of the South Aegean Islands, where isolated endemic species have evolved in intimate, and sometimes deadly, coexistence.

The first hints of the crab-frog conflict came not from scientists but from the guards of the local management unit of the Dodecanese, who reported unconfirmed incidents of frog predation by crabs. During annual fieldwork carried out under the implementation of Greece’s national action plan for the conservation of the Karpathos frog, researchers confirmed those reports in striking fashion. They noticed many frogs with amputated limbs or digits, as well as adults bearing trunk scars, clear evidence that a predator equipped with a sharp instrument had attempted to capture them. These injuries, widespread across the frog population, indicated that the June 2021 encounter was no isolated curiosity but part of a recurring pattern of attacks.

The second fully documented predation event unfolded on 3 December 2023, again along the Argoni Stream, this time at an elevation of 185 meters. At 11:47 in the morning, an adult frog with a snout-vent length of approximately 52 millimeters jumped into the water. Almost instantly, a crab with a carapace width of roughly 70 millimeters emerged from beneath a stone and seized the frog with its chelae, the powerful pincers that define freshwater crabs. The frog struggled to escape, but the crustacean held it underwater with a firm grip on the hind part of its trunk. The crab then immobilized its prey completely, grasping one hind limb with one chela while maneuvering its other chela toward the frog’s body.

What followed was a methodical killing sequence that the researchers documented in photographs. When the crab squeezed the frog’s neck for several seconds, the frog stopped reacting. After a few minutes, during which the frog lost consciousness, the crab began to consume its prey, starting from the outer side of the thigh base. The precision of the attack, with one pincer holding a limb while the other compressed the neck, suggests a practiced predatory technique rather than a chance encounter gone wrong. Combined with the June 2021 observation and the numerous scarred and maimed frogs seen in the field, the evidence points to crabs regularly preying on Karpathos water frogs whenever the two species share the same confined waters.

The root of the conflict lies in the island’s worsening water scarcity. From April to October, when rain essentially ceases on Karpathos, frogs and crabs are forced to cohabitate in the same shallow ditches. The small river puddles that constitute their main habitat are becoming increasingly scarce due to prolonged drought, particularly during the long Aegean summer. As a result, the two species now coexist in microhabitats that can be as restricted as 30 square centimeters in width and 3 centimeters in depth. In ponds this small, encounters between predator and prey are inevitable, and apparently they frequently end in predation attempts by the crab. Climate-driven drying across the Mediterranean means this squeeze is likely to intensify, forcing ever more frequent and deadly meetings in the island’s shrinking wet refuges.

Designing effective conservation measures for the frog is far from straightforward, and the researchers are candid about the complexity of the problem. The crab cannot simply be removed from the equation: Potamon karpathos is a native species and an integral part of the island’s ecosystem, so eradication is neither feasible nor desirable. Meanwhile, the water scarcity that forces the two species into the same microhabitats is a landscape-scale challenge that no single intervention can solve. Any mitigation strategy must therefore balance the protection of an endangered endemic amphibian against the preservation of a native crustacean, all within habitats that are themselves under threat from drought, wildfire, and habitat degradation. The ongoing national action plan for the Karpathos frog, which runs through December 2025, is expected to shed light on these questions and inform the next generation of conservation decisions.

For now, the image of a crab strangling a frog in a ditch on a remote Aegean island stands as a vivid reminder that conservation threats can come from unexpected quarters, including native species behaving in ways no one had documented before. The researchers emphasize that further investigation of the interactions between Pelophylax cerigensis and Potamon karpathos is urgently required, since these predator-prey dynamics have direct implications for the frog’s survival. As drought tightens its grip on the South Aegean and freshwater bodies dwindle, the lethal grip of the crab may become an ever more common feature of life for an amphibian already fighting for its existence on one of Europe’s most isolated outposts.

Subject of Research: First documented predation of the endangered Karpathos water frog by the freshwater crab Potamon karpathos in Greece

Article Title: Lethal grip for an endangered endemic frog: The freshwater crab Potamon karpathos ( Decapoda , Potamidae ) preys on Karpathos water frog Pelophylax cerigensis ( Anura , Ranidae )

Article References: Christopoulos, A., Kotselis, C., Protopappas, D., Spaneli, V., & Pafilis, P. (2024). Lethal grip for an endangered endemic frog: The freshwater crab Potamon karpathos (Decapoda, Potamidae) preys on Karpathos water frog Pelophylax cerigensis (Anura, Ranidae). Herpetozoa, 37, 295-298. https://doi.org/10.3897/herpetozoa.37.e132815

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.37.e132815

Keywords: Karpathos water frog, Pelophylax cerigensis, Potamon karpathos, freshwater crab, predation, endangered species, Greece, amphibian conservation, Herpetozoa, Aegean Islands, water scarcity, invertebrate predation

The tropical clawed frog, an ephemeral pond-breeder from west-central Africa, was discovered reproducing in a Florida wetland in 2016, marking the first documented invasion of this species anywhere outside its native range. Its congener, the African clawed frog, is a notorious global invader implicated in spreading chytrid fungus, driving declines in native frogs, and consuming protected fish species on four continents. The prospect of another Xenopus establishing a foothold in North America has therefore alarmed invasion biologists. Field surveys following the initial discovery found larval stages in up to sixteen ponds, all of them ephemeral and largely fishless, a pattern that hinted the tadpoles might be defenceless against predatory fish.

That observation inspired a team of researchers to test a refined version of Elton’s classic biotic resistance hypothesis, which posits a negative relationship between biodiversity and invasibility. Rather than treating resistance as a diffuse community-level effect driven mainly by competition, the researchers focused on a single strongly interacting native predator and asked how its impact varies across the frog’s complex life history. Their central hypothesis was straightforward: the strength of predatory biotic resistance would depend on the life stage of the invader, with eggs and larvae bearing the brunt of the attack while metamorphosed juveniles and adults escape largely unscathed.

To test this, the team ran a series of controlled laboratory and mesocosm experiments using wild-caught frogs from the invasion site in Riverview, Florida, together with tadpoles produced through hormonally induced spawning of captive stock. Six life stages were exposed to mosquitofish: eggs, hatchlings averaging 12.4 millimetres in total length, small tadpoles, large tadpoles, metamorphs with forelimbs visible, and fully metamorphosed juveniles and adults. Each trial paired treatment tanks containing four mosquitofish, two males and two females to account for sex differences in aggression, with fish-free controls. Observers recorded chases and bites during a twenty-minute window, then monitored survival for a week, noting tail damage on any casualties.

The results were stark. Mosquitofish consumed all but one egg within a single hour, while control tanks lost only a single egg. No hatchling survived exposure to the fish, and mortality reached 86 percent among small tadpoles and a complete 100 percent among large tadpoles, every one of which showed characteristic tail damage inflicted by fin-nipping fish. Mortality dropped to 65 percent for metamorphs, whose tails are being reabsorbed as limbs take over locomotion, and vanished entirely for juveniles and adults. The pattern reveals a vulnerability window that closes abruptly at metamorphic climax, when functional limbs and a reduced reliance on the tail remove the very structure mosquitofish exploit.

Tail damage emerged as the signature of mosquitofish attack. Although direct chases and bites were rarely witnessed during observation periods, with only 32 interactions recorded across 32 tanks, the injuries on survivors told a different story. Damaged tails impair swimming, hindering a tadpole’s ability to reach the surface to breathe, find food, or flee predators. The researchers suggest that many fatal attacks occurred outside the observation window, and that sub-lethal harassment may be as important as outright predation in driving mortality.

The team then probed three factors that might modify this resistance: predator density, cannibalism by adult frogs, and habitat complexity. Stocking densities of 5, 11, and 25 fish per square metre, comparable to wild mosquitofish densities, all produced devastating tadpole losses in outdoor concrete vats. The two higher densities killed 99.7 percent of tadpoles within a week, while even the lowest density caused mortality far exceeding the 8 percent seen in fish-free controls. Contrary to expectations, structural complexity in the form of artificial vegetation at stem densities up to 246 stems per square metre offered no refuge; tadpoles, which filter-feed in the water column and must surface to breathe, remained easy targets regardless of how much cover was available.

The most unexpected finding came from the cannibalism experiment. Adult tropical clawed frogs alone caused almost no tadpole mortality, but when adults were combined with mosquitofish, tadpole deaths soared to an average of 96 percent, frequently exceeding the mortality caused by fish alone. This points to a rare multi-predator facilitation effect, in which mosquitofish fin-nipping likely cripples tadpole mobility, making them easier prey for cannibalistic adults. Facilitation between predators is uncommon in ecological literature, and facilitation of cannibalism by another predator is rarer still, making this observation a notable addition to invasion ecology.

From a theoretical standpoint, the study underscores that biotic resistance acts differentially across the full life cycle of an organism and at different stages of the invasion process itself, potentially blocking establishment or spread before reproduction succeeds. From an applied standpoint, the implications are tantalising. Stocking mosquitofish into ephemeral wetlands that lack natural fish colonisation could function as a stage-based biocontrol, eliminating TCF eggs and tadpoles before metamorphosis and thereby cutting off recruitment. The researchers caution, however, that mosquitofish have their own history of global invasion and can harm native amphibians, so deployment must be restricted to their native range and to situations where threatened species are not breeding.

Field trials are now underway to determine whether laboratory results translate to the patchwork of Florida ponds where the invasion is unfolding. If they do, the humble mosquitofish, a species routinely condemned as an invader on other continents, may earn an unlikely redemption as a home-grown guardian, demonstrating that the strongest barriers to invasion are sometimes written not in species richness but in the precise timing of a predator’s appetite.

Subject of Research: Stage-specific predatory biotic resistance by eastern mosquitofish against invasive tropical clawed frogs

Article Title: Stage-based biotic resistance to a non-native species

Article References: Everett, K. M., Hill, J. E., & Tuckett, Q. M. (2026). Stage-based biotic resistance to a non-native species. NeoBiota, 105, 47-65. https://doi.org/10.3897/neobiota.105.165389

Image Credits: AI Generated

DOI: 10.3897/neobiota.105.165389

Keywords: biotic resistance, invasive species, tropical clawed frog, mosquitofish, Florida, amphibian conservation, predation, metamorphosis, biocontrol, invasion ecology, tadpole survival, habitat complexity

The genus Leptobrachella, part of the family Megophryidae, is the largest clade within that family, currently encompassing 105 recognized species. These small amphibians are spread across a remarkable range, from southern China, northeastern India, and Myanmar, through Thailand and Vietnam, and extending to the Malay Peninsula, Borneo, and Natuna Island. During the breeding season, Leptobrachella species typically perch on rocks along stream banks, where males call to attract females. Despite their diversity, the genus is notorious for its morphological conservatism: species look so alike that past estimates of diversity and evolutionary relationships have been repeatedly misled by high levels of similarity and rampant homoplasy. Molecular phylogenetic frameworks have consequently proposed large numbers of cryptic species, and in the past five years alone, more than thirty percent of the species currently recognized in the genus have been formally described.

This explosion of new species descriptions has made integrative taxonomy, which combines morphology, genetics, and bioacoustics, essential for untangling the true diversity of the group. Vocalizations are particularly powerful tools in this effort. Nearly all species of anuran amphibians are capable of vocalization, and researchers have organized frog calls into four broad functional types: feeding calls, aggressive calls, reproductive calls, and defensive calls. Reproductive calls include advertisement calls, courtship calls, amplectant calls, release calls, post-oviposition male release calls, and rain calls. Among these, advertisement calls, the signals males produce to attract mates and signal their presence to rivals, exhibit substantial variation across species. This variation makes them a viable foundation for systematic classification and, crucially, for the identification of cryptic species that are nearly indistinguishable by eye.

Leptobrachella dushanensis was formally described as a new species from southern China in 2024, but no information about its acoustic signals existed in the literature. To fill this gap, researchers visited the species’ type locality in Dushan County on the night of April 1, 2024, between 19:00 and 23:00 hours. Conditions at the site were warm and extremely humid, with air temperatures of 17.0 to 19.0 degrees Celsius and ambient humidity of 98 percent. The team recorded a total of 197 calls from three adult males, using a Sony ICD-PX470 digital recorder at a sampling rate of 44.1 kHz and 16-bit resolution, with the microphone held within half a meter of each calling animal. All recordings came from isolated individuals, with no overlapping calls or mixed choruses, and were saved as WAV files for analysis. The researchers have made these recordings publicly available through the Figshare repository.

Species identity was verified with rigorous rigor. Snout-vent lengths of all recorded males were measured in situ with a precision digital caliper to the nearest 0.1 millimeter, ranging from 31.9 to 32.6 millimeters. One male was collected as a voucher specimen, euthanized with isoflurane, fixed in ten percent buffered formalin, and deposited at the Moutai Institute in China, with tissue samples preserved separately in 95 percent ethanol before fixation. The mitochondrial COI gene was extracted, amplified, sequenced, and uploaded to GenBank under accession number PQ288957, confirming that the calling frogs were indeed Leptobrachella dushanensis. The remaining recorded males were released back to their original habitat after measurement.

Acoustic analysis was performed with Raven Pro 1.6, following call-centred terminology in which the fundamental unit is a call, each call contains a single note, and each note contains several pulses. Only calls with high signal-to-noise ratios, free from overlapping calls of nearby males, were analyzed. The results revealed a remarkably consistent signal: the advertisement call of Leptobrachella dushanensis consists of a single note with a duration of 78.19 to 123.78 milliseconds, delivered at intervals of 394.88 to 499.59 milliseconds, yielding call rates of 1.78 to 2.31 calls per second. Each call contained 14 to 21 pulses produced at a rapid rate of 164.26 to 174.06 pulses per second. The dominant frequency, the frequency carrying the most acoustic energy, fell in a narrow band between 4.84 and 4.91 kilohertz, and no obvious harmonics were detected.

The amplitude structure of the call followed a distinctive pattern. In every recorded call, the amplitude peaked at the very beginning of the signal and then gradually decreased. About one-third of the way into the call, the amplitude rose again, though it never exceeded the initial peak, before declining steadily until the call ended. Males were observed calling from rocks in streams surrounded by shrubs, a typical setting for the genus during the breeding season.

To test whether these acoustic traits could distinguish the new species from its closest relative, the team also recorded Leptobrachella dong, the sister species of L. dushanensis. Working in Congjiang County, also in Guizhou Province, on March 4, 2022, at temperatures of 12.0 to 13.0 degrees Celsius and 90 percent humidity, they captured 117 calls from four males with snout-vent lengths of 29.4 to 29.8 millimeters. Molecular verification again confirmed the species identity via a COI sequence deposited in GenBank under accession number PQ438741. The calls of L. dong showed a broadly similar architecture: single-note, pulse-repetition calls with an initial amplitude peak, a mid-call dip, and a secondary rise around two-thirds of the way through that again failed to surpass the opening peak. Dominant frequency was a uniform 4.82 kilohertz, again without obvious harmonics.

Despite these structural similarities, the two species are acoustically separable on several parameters. L. dong calls are shorter, lasting 63.54 to 90.82 milliseconds, are delivered faster at rates of 2.23 to 2.72 calls per second, contain fewer pulses, only 9 to 11, at a markedly slower pulse rate of 102.13 to 133.77 pulses per second. A principal component analysis of the combined call dataset confirmed the separation quantitatively. The first two principal components together explained 79.77 percent of the total variance, with PC1 accounting for 62.09 percent and loading primarily on temporal parameters, including the number of pulses, call duration, and pulse rate, while PC2 explained 17.69 percent and was driven mainly by dominant frequency. In the resulting PC space, the calls of the two species showed no overlap at all, providing clear acoustic evidence supporting the taxonomic differentiation of L. dushanensis.

The findings also carry broader phylogenetic interest. L. dushanensis belongs to the L. oshanensis species group, whose members typically produce more complex advertisement calls, often with multiple call types. Unlike its relatives, L. dushanensis produced only simple calls in the recordings, and its call differs considerably from those of group members such as L. yeae, L. jinyunensis, L. chishuiensis, L. bijie, L. jinshaensis, L. suiyangensis, L. purpuraventra, L. wulingensis, and L. oshanensis, all of which exhibit multiple advertisement call types. Its dominant frequency of roughly 4.88 kilohertz is also lower than the 6.70 kilohertz reported for L. alpian. As more researchers adopt acoustic diagnostic traits to identify cryptic species in taxonomic studies, detailed descriptions like this one become indispensable. For a genus in which species are highly morphologically conserved, the species-specific nature of the Dushan Leaf Litter Toad’s call not only reinforces its status as a distinct species but also lays the basic groundwork for future behavioral, physiological, and ecological studies of Leptobrachella frogs across Asia.

Subject of Research: First description of the advertisement call of the frog Leptobrachella dushanensis and its bioacoustic distinction from its sister species Leptobrachella dong

Article Title: The advertisement call of Leptobrachella dushanensis ( Anura , Megophryidae )

Article References: Liu, J., Cheng, Y., Li, S., Cheng, G., & Wei, G. (2024). The advertisement call of Leptobrachella dushanensis (Anura, Megophryidae). Herpetozoa, 37, 373-378. https://doi.org/10.3897/herpetozoa.37.e136688

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.37.e136688

Keywords: Leptobrachella dushanensis, advertisement call, bioacoustics, anuran vocalization, Megophryidae, cryptic species, integrative taxonomy, Guizhou Province, principal component analysis, amphibian conservation, dominant frequency, sister species

The research team, led by scientists at the University of Liège, set out to answer two questions that have long frustrated conservationists. First, which environmental conditions actually determine where Japanese giant salamanders can live? Second, how will those conditions shift as the planet warms? To do this, they deployed species distribution models, a cornerstone tool of modern macroecology, over an area of 282,916 square kilometres covering the entirety of Honshu, Shikoku and Kyushu islands. The models compared 477 high-resolution occurrence records, gathered from field surveys and published studies dating back to 1970, against seven remote-sensing environmental predictors spanning climate, topography and land use.

The occurrence data required careful preparation. The team collected 1,228 presence records in total, but to avoid spatial autocorrelation and overfitting, they thinned the dataset so that no two points fell within one kilometre of each other, a distance chosen because it matches the grid scale of the environmental data and the typical migratory range of the species. The result was a robust set of 477 presence points on which to train the models. Environmental predictors were selected based on the salamander’s ecology: four bioclimatic variables from the WorldClim dataset, including mean temperature of the wettest and warmest quarters and precipitation of the warmest and coldest quarters, alongside mean slope, agricultural area and urban area, all at a one-square-kilometre resolution.

The modelling itself used MaxEnt, a presence-background method that compares the environmental conditions at species locations with those available across the landscape. To ensure the model captured conditions specific to the salamander’s actual range, the team restricted the background to the known distribution during training, then projected the model across all of Japan to explore potential suitability beyond it. They corrected for sampling bias using a bias grid built from a minimum convex polygon around occurrence points buffered by 50 kilometres, and partitioned the data spatially into four folds to improve transferability across space and time. Model calibration tested 36 parameter combinations of feature classes and regularisation multipliers, with the optimal model selected using corrected Akaike Information Criteria and validated against null models built from 100 iterations.

The findings are striking. Climatic variables dominated the distribution model, contributing 76.21 percent of the total, with precipitation of the warmest quarter alone accounting for 36.73 percent. The salamanders favour areas with moderate precipitation during cold and wet seasons and mild summer temperatures, with the highest probability of presence at average air temperatures around 20 to 24 degrees Celsius. Excessive precipitation proved detrimental, with suitability dropping sharply above 500 millimetres in the wettest quarter, likely because strong currents and prolonged flooding threaten larvae and disrupt the submerged nests that males guard. Slope also mattered, with suitability rising up to a mean of 17 percent before declining in steeper terrain, while land-use variables contributed relatively little.

Perhaps the most unexpected result concerns geography. The current habitat suitability map reveals highly suitable areas both within and beyond the species’ known range. In the northern part of Honshu Island, far from any confirmed salamander populations, the model identified 42,508 square kilometres of high-suitability habitat. Yet the salamanders cannot reach them. The Japanese Alps, a mountain chain bisecting Honshu, form an impassable natural barrier for a fully aquatic species that cannot climb terrestrial environments outside of riverine areas. The team’s analysis suggests that climatic differences between northern and southern Japan do not explain the species’ absence in the north; rather, it is the biogeography of the Alps that has confined the salamander to the south-western regions of the island.

Within the current distribution range, which covers 59,193 square kilometres, the picture is already mixed. Thirty percent of the area was identified as unsuitable, 37 percent as low suitability, 22 percent as moderate and just 11 percent as high suitability. The projections for the future are more alarming. Considering the extent of the current range, more than 50 percent of the geographic area is expected to lose habitat suitability at any point between 2050 and 2090, under both the optimistic SSP126 scenario and the pessimistic SSP370 scenario. The most severe loss, affecting 64.5 percent of the area, is predicted for 2090 under the pessimistic scenario. Gains in suitability do occur, reaching 14.5 percent of the area in 2070 under the optimistic scenario, but they are insufficient to offset the losses.

The mechanisms behind these projected losses are rooted in the salamander’s physiology. Japanese giant salamanders prefer relatively cold mountainous streams with high levels of dissolved oxygen, which promotes cutaneous respiration. Rising air temperatures raise water temperatures and reduce dissolved oxygen concentrations, a critical parameter for survival. Heavy and sustained rainfall is also expected to increase across Japan, raising the frequency of flooding events that particularly affect larval stages and nesting sites. A study on the North American giant salamander, or hellbender, showed that a two-degree increase in water temperature decreased immune function and growth rate while increasing physiological stress, offering a sobering parallel for what warming may mean for the Japanese species.

The conservation implications are complex. The species was reassessed from Near Threatened to Vulnerable on the 2022 IUCN Red List, but many populations are declining and the salamander’s long life expectancy makes the true status of populations difficult to assess. Habitat fragmentation from dams, built for agriculture and flood control, blocks movement along waterways and reduces breeding microhabitat availability. Without connectivity between habitats, even the suitable areas identified by the models would be inaccessible to the salamanders. Interestingly, the declining human population in rural Japan may offer some relief, as unmaintained agricultural dams eventually burst and restore connectivity, though new flood-control infrastructure linked to climate change threatens many habitats.

The study calls for new surveys based on the projected maps, particularly on Shikoku and Kyushu islands where distribution data remain sparse, and for fine-scale research on disturbances to aquatic habitats. Environmental DNA surveys could identify previously unknown populations, followed by visual confirmation at positive sites. Because giant salamanders act as top predators structuring aquatic communities, protecting their habitat may benefit other species relying on the same streams, an umbrella effect that amplifies the conservation value of every stream saved. As climate change tightens its grip on the cold, clear waters these ancient creatures depend upon, the race is on to understand and preserve what remains of their world before the living fossil becomes a fossil in fact.

Subject of Research: Projected climate-driven loss of habitat suitability and distribution range of the endangered Japanese giant salamander

Article Title: Loss of habitat suitability and distribution range of the endangered Japanese giant salamander under climate change

Article References: Duret, C., Bartet, T., Hambuckers, A., Kishida, O., Okada, S., Taguchi, Y., Takahashi, M. K., & Denoël, M. (2025). Loss of habitat suitability and distribution range of the endangered Japanese giant salamander under climate change. Frontiers of Biogeography, 18, Article e133105. https://doi.org/10.21425/fob.18.133105

Image Credits: AI Generated

DOI: 10.21425/fob.18.133105

Keywords: Japanese giant salamander, Andrias japonicus, climate change, species distribution models, MaxEnt, habitat suitability, amphibian conservation, biogeography, Japanese Alps, habitat fragmentation, Frontiers of Biogeography, freshwater megafauna

The jambato’s near-disappearance was not an isolated tragedy. Across the Neotropics, harlequin toads of the genus Atelopus suffered catastrophic population collapses driven by a combination of threats, including the deadly chytrid fungus Batrachochytrium dendrobatidis, the destruction of habitats as agricultural frontiers expanded, and the impacts of introduced species such as rainbow trout, Oncorhynchus mykiss, which prey on native amphibians in Andean streams. The genus became a global symbol of the amphibian extinction crisis, with dozens of species vanishing or declining toward oblivion. Against this grim backdrop, the survival and rediscovery of A. ignescens stands out as a rare story of resilience, and every new piece of biological information about the species carries weight for its ongoing protection.

Despite decades of research on the taxonomy and conservation of Atelopus, their acoustic communication has remained remarkably poorly understood. Of the roughly 100 recognized species in the genus, vocalizations have been described for only about 24. In Ecuador, home to 25 Atelopus species, the calls of only one other species, A. exiguus, had previously been documented. Part of the reason for this gap is anatomical: the vast majority of Atelopus species lack a tympanic middle ear, the structure that in most frogs transmits sound vibrations to the inner ear. Without eardrums, these frogs were long assumed to be effectively deaf, a presumption that discouraged bioacoustic research and led to misconceptions about their capacity for acoustic communication.

The new study dismantles that assumption. Working at Angamarca, in the western foothills of the Andes within an ecosystem of evergreen shrubland, páramo grassland and agricultural mosaic, the researchers recorded the vocalizations of an adult male jambato calling from grasses and herbaceous vegetation at ground level. The recordings, made between 10:00 and 12:00 on December 8, 2021, were captured using a cell phone storing audio in FLAC format at a sampling rate of 44.1 kHz and 24-bit resolution, then converted to WAV and analyzed with the bioacoustic software Raven 1.6 using standardized spectral and temporal parameters. The recordings are now archived at the Laboratorio de Biología Evolutiva of Universidad San Francisco de Quito and at the Fonoteca Zoológica of the Museo Nacional de Ciencias Naturales in Madrid, ensuring the data remain available for future comparison.

The analysis revealed a repertoire of three distinct call types, classified as tonal, short and pulsed calls, spanning a structural continuum from non-pulsed to pulsed emissions. Tonal calls, defined by durations exceeding 100 milliseconds, typically show a downward frequency modulation, sometimes with a more complex upward-downward pattern. Short calls last no more than 100 milliseconds and also descend in frequency. Pulsed calls, by contrast, consist of repetitive bursts of 13 to 15 individual pulses, each lasting no more than 21 milliseconds. Across all call types, the mean dominant frequency sits at about 1.7 kHz, with mean minimum and maximum frequencies of roughly 1.50 and 1.78 kHz respectively, and the calls are generally downward frequency modulated at a mean rate of about 1.66 Hz per millisecond.

The temporal structure of the repertoire is equally distinctive. Calls averaged 370 milliseconds in duration but were emitted at long intervals averaging about 7.5 seconds, producing a mean call rate of roughly 11 calls per minute. Individual calls comprised a mean of about 1.6 notes, with note durations averaging 66 milliseconds delivered at a rate of about 2.9 notes per second, while pulses within pulsed calls averaged 7.67 milliseconds in duration at a rapid mean rate of about 90 pulses per second. Amplitude envelopes varied systematically among call types: tonal calls reached maximum amplitude quickly, with a mean rise time of about 36 percent of total call duration followed by a slower decay, whereas short calls showed a more balanced, progressive rise and decay of roughly equal proportions.

Perhaps the most striking quality of these vocalizations is their sheer subtlety. The calls are low-intensity sounds that the researchers compare to the whispering of rodents, and the short non-pulsed call type was not even discernible to the human ear at the moment of recording. This faintness echoes an anecdotal description from 1973, when the naturalist Peters characterized the jambato’s calls as a slight, low sound difficult to hear even at close range. Such inconspicuous vocalizations likely contributed to the long-standing belief that these frogs barely vocalize at all, and they raise fascinating questions about how the signals function in the dense grasslands and rushing streams of Andean páramo habitat, where visual signals such as the species’ diurnal displays may complement or even outweigh acoustic ones.

The question of how a frog without a tympanic middle ear can hear at all remains one of the most intriguing puzzles surrounding the genus. The absence of eardrums does not mean harlequin toads are deaf; evidence suggests they rely on extratympanic mechanisms of audition, pathways by which sound reaches the inner ear through other routes, such as transmission through body tissues or the lungs. Similar mechanisms have been proposed for other earless frogs, but the details for Atelopus remain poorly resolved. The authors emphasize that much more research is needed to understand these alternative hearing pathways and to determine the relative importance of acoustic communication in a genus whose behavior is otherwise characterized by multimodal signaling that integrates both auditory and visual components.

The bioacoustic baseline established for A. ignescens carries practical consequences beyond pure curiosity. Because each call type has now been quantified with precise spectral and temporal parameters, conservationists can deploy passive acoustic monitoring, autonomous recorders that listen continuously in the field, to detect jambato populations in remote Andean localities without disturbing them. Such methods could reveal new surviving populations and help track the species’ recovery over time. Acoustic data may also help resolve lingering taxonomic uncertainties within the species complex, since call structure often serves as a diagnostic character distinguishing closely related frog species. Given that A. ignescens was the first amphibian species ever described from Ecuador, in 1849, the fact that its voice went formally undocumented until now underscores how much fundamental biology remains to be discovered even about the most iconic species.

The jambato’s story has become a touchstone for amphibian conservation across Ecuador and the wider Neotropics, a reminder that species written off as extinct can persist in refuges waiting to be found. By endowing this resilient frog with an acoustic identity, the researchers have added a new dimension to efforts to comprehend and preserve it. The whisper of the jambato, nearly lost amid one of the worst extinction crises ever to strike a vertebrate class, has now been heard, measured and archived. Whether those faint calls guide scientists to more hidden populations, or inspire deeper investigation into how earless frogs perceive sound, they ensure that this Andean survivor will not be disappearing quietly, and that its subtle voice will not fall on truly deaf ears.

Subject of Research: First description of the vocal repertoire of the rediscovered Ecuadorian harlequin frog Atelopus ignescens

Article Title: Vocalizations of Atelopus ignescens (Cornalia, 1849): The repertoire of a resilient species that whispers not to disappear

Article References: Batallas, D., Guayasamin, J. M., & Vega-Yánez, M. A. (2024). Vocalizations of Atelopus ignescens (Cornalia, 1849): The repertoire of a resilient species that whispers not to disappear. Herpetozoa, 37, 421-428. https://doi.org/10.3897/herpetozoa.37.e134923

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.37.e134923

Keywords: Atelopus ignescens, jambato, harlequin toads, bioacoustics, amphibian conservation, Ecuador, Andes, extratympanic hearing, chytrid fungus, passive acoustic monitoring, Herpetozoa, rediscovered species

The research team, led by Amaël Borzée of Nanjing Forestry University with collaborators including Christophe Dufresnes and Yikweon Jang, sampled the complex between 2016 and 2019 in six countries: the Republic of Korea, the Democratic People’s Republic of Korea, China, Russia, Mongolia, and Japan. Fieldworkers located calling males, recorded their advertisement calls with linear PCM recorders and unidirectional microphones, caught and measured individuals with digital callipers to the nearest 0.1 millimetre, and collected genetic material through oral swabs stored at minus 20 degrees Celsius. In total, 294 new individuals were barcoded for four mitochondrial gene fragments, alongside call recordings from 194 individuals and morphometric data from 314 frogs.

The mitochondrial evidence was decisive. Sequences of roughly 900 base pairs of cytochrome-b, 450 base pairs of COI, about 1,000 base pairs of the 16S-ND1 region, and 900 base pairs of 12S rRNA, concatenated into a 3.2-kilobase alignment, revealed two major clades. Clade A occupies Sakhalin Island in Russia, northeastern Japan, and Central Japan, while clade B lives in southwestern Japan and across the Asian mainland. The two clades diverged during the Late Miocene, approximately 6.1 million years ago, with a 95 percent highest posterior density interval of 5.3 to 7.0 million years. Notably, the researchers barcoded both matrilines in Kyoto, pinpointing a contact zone in central Japan where the two species meet.

Genome-wide nuclear data independently confirmed the split. Using RAD-sequencing, the team assembled a 42.8-kilobase nuclear alignment containing 2,302 single nucleotide polymorphisms. Three phylogenetic reconstruction methods — maximum likelihood with PhyML, time-calibrated Bayesian inference with BEAST, and the coalescent-based species tree method SNAPP applied to variable sites only — produced identical topologies with fully supported internal nodes. The nuclear divergence was dated to 5.9 million years ago, closely matching the mitochondrial estimate, with a net genetic distance of 0.23 percent across the RAD-seq alignment. This convergence between mitochondrial and multilocus nuclear evidence rules out the possibility that the earlier split was an artefact of single-gene inference, a known pitfall in anuran phylogeography.

Within each species, the story is subtler. Clade B, now assigned the name Dryophytes japonicus, splits into Japanese populations (subclades B1, B2, and B3) and mainland populations (subclades B4 and B5), separated around 1.2 million years ago during the Pleistocene. The mainland lineage B4 is restricted to the southern Korean Peninsula and Jeju Island, while B5 extends along the Baekdudaegan mountain range and northwards into Mongolia, China, and Russia, with three haplogroups mapped within it. Clade A, provisionally labelled D. cf. japonicus because no available scientific name fits it, divides into a northern group (A1 and A2, spanning Sakhalin, Hokkaido, and northern Honshu) and a southern group (A3 and A4, in Central Japan and Sado Island), separated roughly 2.7 million years ago.

Phenotypic analyses added an unexpected twist. Principal component analysis of call properties — high and dominant frequencies, note duration, effective amplitude, and fundamental frequency — showed significant differences among the four subclades, with all MANOVA results significant at p below 0.001. Morphometric PCA, built from twelve characters including head width, hind-limb length, and tympanum diameter, also yielded significant differentiation. Yet phenotypic divergence did not track molecular divergence cleanly. The deeply diverged northern Japanese group A1&A2 and the mainland group B4&B5, separated by sea straits and belonging to distinct species, remain phenotypically similar, possibly reflecting convergence towards similar ecological optima. Conversely, parapatric subclades such as A3&A4 and B1&B2&B3 show significant phenotypic differences, a pattern the authors suggest could fit a hypothesis of reinforcement, where character shifts in mating traits reduce the costs of interbreeding.

Taxonomic decisions hinged on a historical puzzle. The oldest name for the complex, Hyla arborea var. japonica, was described by Günther in 1858 from syntypes collected by Siebold and Bürger with the vague type locality of Japan. Because both clades inhabit the country, the name could apply to either species. The researchers relied on two anecdotal clues: Siebold was posted to Dejima Island off Kyushu, the only area easily accessible to westerners in mid-nineteenth-century Japan, and Boulenger, a contemporary of Günther, explicitly distinguished Hyla stepheni from the Japanese H. arborea var. japonica by referring to Kyushu. The team therefore assigned the name D. japonicus to the southern Japanese and mainland species, recommending Northern Asian treefrog as its common English name, and provisionally called the mainland subspecies D. j. cf. stepheni, with Geomun’s treefrog as a common name chosen to avoid colonial heritage. The northern species remains unnamed as D. cf. japonicus.

Conservation assessments followed the IUCN Red List categories and criteria for each delimited lineage. Despite relatively narrow ranges for several lineages, none currently crosses the threshold for listing as threatened. Population sizes are likely above 10,000 individuals, declines are unlikely to reach the 30 percent threshold under criterion A, and geographic ranges are unlikely to fall below 20,000 square kilometres under criterion D. However, the authors caution that narrow mitochondrial lineages such as A3 on Sado Island, and B1, B2, and B3 in Japan, may fit threatened criteria if assessed separately, and observed declines in northern China, eastern Mongolia, and adjacent Russia warrant further surveys. Climate change poses a moderate-to-high risk under the 1.5 degree Celsius scenario, with air temperatures in northeast Asia predicted to rise by 2.7 degrees Celsius and humidity by 3.3 percent.

The broader lesson is one that echoes far beyond treefrogs. Species complexes listed as abundant can mask threats to individual lineages, much as tigers are divided into six evolutionary clades with wildly different conservation situations, from increasing populations in Nepal to the extinct Caspian tiger. The authors argue that conserving the full diversity of the D. japonicus complex will require proper population monitoring and additional genomic investigations to determine whether the unnamed delimited lineages merit formal taxonomic descriptions. Half of the phylogeographic diversity in this complex has now received taxonomic attention; the other half, and the evolutionary history it represents, still hangs in the balance.

Subject of Research: Evolutionary biology and conservation of the Dryophytes japonicus treefrog complex

Article Title: Integrating phylogeographic and phenotypic evidence to delimit deep evolutionary lineages in the Dryophytes japonicus species complex, with an assessment of their conservation needs

Article References: Borzée, A., Jang, Y., Othman, S. N., Groffen, J., Maslova, I. V., Purevdorj, Z., Yasumiba, K., Shimada, T., Yi, Y., Schepina, N. A., Andersen, D., Bae, Y., Miura, I., & Dufresnes, C. (2025). Integrating phylogeographic and phenotypic evidence to delimit deep evolutionary lineages in the Dryophytes japonicus species complex, with an assessment of their conservation needs. Herpetozoa, 38, 25-42. https://doi.org/10.3897/herpetozoa.38.e137747

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.38.e137747

Keywords: Dryophytes japonicus, species delimitation, phylogeography, RAD-sequencing, mitochondrial barcoding, bioacoustics, morphometrics, integrative taxonomy, IUCN Red List, amphibian conservation, northeast Asia, cryptic species

Researchers conducted systematic field surveys and long-term in situ monitoring at the type locality of Boulenophrys elongata, located on Mt. Lianhua in Huidong County, Guangdong Province. The study area, situated at elevations between 700 and 1000 meters above sea level, features flowing montane streams and nearby forest floors within subtropical evergreen broad-leaved forests. By collecting five adult individuals during the breeding season, the team enabled the supplementation of morphological diagnoses and the establishment of baseline ecological data. These specimens, including three adult males and two adult females, were fixed in 10% buffered formalin and later transferred to 70% ethanol for detailed examination. The collection of these breeding individuals was crucial for clarifying the sexual dimorphism that had remained insufficiently clarified in previous studies, providing the first empirical support for population assessments and conservation strategies for this montane amphibian.

The morphological analysis revealed distinct sexual dimorphism that was absent in the original type series. Adult males measured between 27.8 and 30.2 mm in snout-vent length, while adult females ranged from 34.6 to 37.6 mm. Breeding males exhibited a nuptial pad with dense black nuptial spines at the bases of fingers I and II, a subgular vocal sac, and dense tiny conical spines on their dorsum. These traits, combined with the presence of vomerine ridges and teeth, and a well-developed canthus rostralis, helped refine the morphological diagnosis of the species. The dorsal skin was relatively smooth with dense granules and a weak discontinuous X-shaped ridge on the center of the dorsum, while the limbs featured discontinuous transverse ridges and tubercles. This detailed characterization resolves taxonomic ambiguity and provides a clearer framework for identifying the species in the field, distinguishing it from other members of the genus that often exhibit similar external features but differ in subtle reproductive traits.

Ecological observations indicated that Boulenophrys elongata is strictly associated with flowing montane streams and the adjacent forest floor. The breeding season appears to span from early March to late August, with reproductive activities triggered exclusively by heavy rainfall. Male advertisement calls were recorded during this period, but they ceased if rainfall stopped for several successive days, even under high ambient humidity. This dependence on specific weather conditions highlights the vulnerability of the species to climate variability and habitat fragmentation. The toads inhabit a microhabitat characterized by intricate narrow rock formations and dense shrubs, which provide shelter and breeding sites. Understanding these ecological traits is essential for conservation efforts, as the narrow range and specific habitat requirements make Boulenophrys elongata particularly susceptible to environmental changes and anthropogenic disturbances in the montane regions of southern China.

One of the most significant findings of this study is the first formal documentation of pre-amplexus reproductive behavior in the genus Boulenophrys. Continuous observation of the courtship behavior was carried out for 56 minutes on March 28, 2026, under minimal field disturbance. The sequence began with males establishing calling territories on riparian shrub foliage at approximately 25 cm above the ground. They produced intermittent quack-like advertisement calls via a single subgular vocal sac to attract conspecific females and defend their home ranges. The female, initially stretching its body forward on leaves, adjusted its orientation and crawled towards the male after detecting the calls. This initial interaction set the stage for a complex series of behavioral exchanges that demonstrated the intricate nature of mating strategies in this species.

The courtship process involved several distinct stages, including mutual behavioral recognition and positional adjustment. The male and female engaged in reciprocal blinking responses, which served as typical interactive cues during the assessment phase. The male would cease calling when the female blinked or turned its head, indicating a sensitive response to visual signals from the female. Physical contact occurred when the male touched the posterior margin of the female’s snout with its snout tip and rubbed the digits of the female’s fore-limb with its snout and eyelids. This tactile stimulation, accompanied by vocal signals and blinking, highlighted the multi-modal nature of communication between the sexes. The female’s responses, including head tilts and short jumps, played a crucial role in the progression of the courtship sequence, demonstrating a dynamic interaction that was previously undocumented in the genus.

Following the initial physical contact, the male shifted to a companion-leading courtship strategy, guiding the female towards potential breeding microhabitats. The male crawled steadily towards the direction of the advertisement calls, while the female followed by alternating crawling and jumping. The pair maintained close proximity, with seven intermittent physical contacts occurring throughout the movement. When separated, the male produced calls to re-orientate the female, who responded with a single blink after relocating the male. This guided movement led the pair towards a seepage area concealed within rock crevices, approximately 12 meters away. The observation ended before amplexus could be observed, but the detailed recording of the pre-copulatory sequence provided valuable insights into the mating behavior of Boulenophrys elongata and the broader genus.

The study underscores the importance of sustained field surveys and long-term monitoring for effective anuran conservation. The observed behavioral patterns, including male calling, female assessment, snout contact, and male-led guiding, suggest complex reproductive adaptations in fragmented montane habitats. However, limitations such as interrupted observations due to dense vegetation and rugged terrain, and the restriction to a single recorded event, highlight the need for repeated observations to confirm the consistency and generality of these patterns. The findings provide a comparative framework for behavioral evolution and phylogenetic studies within the genus, emphasizing the value of targeted fieldwork in unraveling the diversified reproductive behavior of Boulenophrys species. This research not only resolves taxonomic ambiguities but also establishes a baseline for future conservation assessments and population monitoring of this narrow-range endemic species.

Subject of Research: Reproductive behavior and sexual dimorphism in Boulenophrys elongata

Article Title: Supplementary description of Boulenophrys elongata ( Anura , Megophryidae ): Sexual dimorphism and observations on reproductive behaviours

Article References: Wang, J., Zhan, B.-B., Tan, L., Xiao, W.-W., Li, Y.-H., Lin, S.-S., & Zeng, Z.-C. (2026). Supplementary description of Boulenophrys elongata (Anura, Megophryidae): Sexual dimorphism and observations on reproductive behaviours. Biodiversity Data Journal, 14, Article e201422. https://doi.org/10.3897/bdj.14.e201422

Image Credits: AI Generated

DOI: 10.3897/BDJ.14.e201422

Keywords: Boulenophrys elongata, sexual dimorphism, reproductive behavior, amphibian conservation, montane streams, courtship ritual, herpetology, Guangdong, horned toads, ecological monitoring, Supplementary, description