New Frog Species Wu’s Short-Legged Toad Discovered in Guizhou China

Deep in the montane streams of Mt. Foding National Nature Reserve in Guizhou Province, China, a toad-like frog has been quietly calling under rocks with a voice like a duck. Scientists have now confirmed that this animal is entirely new to science. In a study published in the journal Zoosystematics and Evolution, researchers describe the species formally as Brachytarsophrys wui, a member of the family Megophryidae, and recommend the common name Wu’s Short-Legged Toad. The discovery brings the number of recognized species in the genus Brachytarsophrys to ten and adds a striking new branch to the amphibian tree of southern China.

The genus Brachytarsophrys is a group of large, cryptic, stream-breeding frogs distributed across the Indochina Peninsula and southern China. These animals are toad-like in appearance, with wide, flattened heads and short limbs, and they inhabit montane streams surrounded by moist, subtropical, evergreen broadleaf forests. Their cryptic behavior and secretive habits have long made them difficult to study. Although the higher-level taxonomy within the subfamily Megophryinae remains debated, the inner group of Brachytarsophrys is easily distinguished from other members by morphology, phylogeny, and ecology. Until now, nine species had been described, two of which occur in the Indochina Peninsula and seven in southern China.

The new species emerged from targeted herpetological surveys conducted between 2019 and 2020 in Mt. Foding National Nature Reserve, a bio-corridor reserve in northeastern Guizhou that lies between Mt. Fanjing and Mt. Leigong. Elevation within the reserve ranges from 500 to 1869 meters, and the area represents a classic montane hotspot for biodiversity and endemicity, although little had been documented about its herpetofauna. During fieldwork from July 2019 to April 2020, the team collected seven adult frogs and four tadpoles from small streams at about 740 to 1000 meters elevation. After photographs were taken, liver tissues were sampled and stored in 95 percent ethanol for DNA extraction, and voucher specimens were deposited at the Museum of Biology of the Guizhou Institute of Biology in Guiyang.

To test whether the Mt. Foding frogs represented a distinct evolutionary lineage, the researchers sequenced two mitochondrial gene segments: 16S ribosomal RNA and cytochrome oxidase subunit I, or COI. A total of 403 base pairs of 16S rRNA and 554 base pairs of COI were concatenated, producing an alignment with 238 variable positions and 169 parsimony-informative sites. Phylogenetic reconstruction was carried out using both maximum likelihood and Bayesian inference, and the two methods resulted in essentially identical topologies. The analyses divided Brachytarsophrys into two highly divergent groups with strong support. Group I contains the two Indochinese species, while all Chinese species belong to Group II, which itself splits into two well-supported clades. The Mt. Foding samples formed a strongly independent lineage, with Bayesian posterior probability of 1.00 and maximum likelihood bootstrap support of 99, and were genetically identical to each other.

Genetic distances between the novel lineage and other Brachytarsophrys species ranged from 0.00 to 5.96 percent in 16S rRNA sequences and from 2.83 to 16.98 percent in COI sequences. The new species clusters closest to B. orientalis, with uncorrected COI p-distances of at least 3.77 percent, a level of divergence consistent with species-level distinction in frogs. The molecular evidence alone would have been suggestive, but the researchers also found a suite of stable morphological differences that distinguish the Mt. Foding population from all known congeners, providing the concordant evidence needed for formal description.

Morphologically, Brachytarsophrys wui is a medium-sized member of its genus, with snout-vent length of 88.1 to 93.2 millimeters in five adult males and 108.7 to 111.2 millimeters in two adult females. The head is very large, wider than long, and nearly one-half as broad as the snout-vent length. The tympanum, or external eardrum, is completely hidden. The dorsal skin is slightly rough with irregularly shaped dark blotches and stripes, and in life the dorsum bears a distinct W-shaped marking between the shoulders. The chin and ventral surface of the throat are rough with brown, irregularly shaped dark markings, and two large longitudinal black-brown stripes run along the lateral throat. The upper eyelid carries tubercles, one of which is enlarged into a prominent, bluntly conical horn. The margin of the tongue is shallowly notched behind, a feature that separates it from the deeply notched tongue of B. popei and the feebly notched tongues of most other congeners.

The toes are markedly webbed, following the formula I (1½)-(2) II (1½)-(3) III (2½)-(4) IV (4)-(2) V, with the webbing extending as a wide fringe along either side of each toe. Males possess a large single subgular vocal sac located laterally on the floor of the mouth, and during the breeding season they develop an indistinct brown nuptial pad on the dorsal surface of the first and second finger bases, covered with dense, tiny black nuptial spines. The tadpoles are equally distinctive, bearing a transverse white stripe on the ventral surface and two longitudinal white stripes along the sides of the body, features absent in the tadpoles of B. orientalis. The oral disk has lips expanded vertically, forming a dorsally oriented funnel.

Natural history observations add further texture to the portrait of the new species. All specimens were collected at night in small streams, with calling males found perching under rocks. Duck-like advertisement calls could be heard during July, and recordings of the holotype, made at an ambient temperature of 19.5 degrees Celsius, revealed single notes with durations of 0.104 to 0.124 seconds, a call repetition rate of 2.3 seconds, and a dominant frequency between 1.0 and 1.2 kilohertz. In one remarkable find, an adult male and a cluster of approximately 1600 eggs were discovered under a rock, suggesting that adult males may exhibit egg protection behavior. Females collected from July to August were gravid, and males were heard calling only from July to the beginning of August, indicating a breeding season concentrated in midsummer. During the surveys, males were observed far more often than females, at a ratio of 16 to 2.

The species is currently known only from Mt. Foding National Nature Reserve, where it is confined exclusively to the Lengshui River and Bingjia River. This narrow distribution, combined with high habitat specificity, makes the species vulnerable. Its breeding habitat is characterized by relatively fast-flowing water with riverbeds containing large cobblestones. The distribution locality underwent intensive anthropogenic disturbance through deforestation in the 1980s, followed by further disturbance from the development of modern tourism. The researchers argue that greater protections for this habitat are warranted to safeguard the new species and other endemic animals sharing its streams.

Beyond the description itself, the study carries a broader message about how much amphibian diversity remains undocumented. Recent phylogenetic analyses have revealed multiple genetic lineages of Brachytarsophrys that may represent additional new species, and the discovery of B. wui in a reserve that had received little herpetological attention demonstrates that intensive, targeted surveying can still uncover animals never before recorded. The Guizhou Karst Plateau, located at the uplifted edge of the Qinghai-Tibet Plateau, is the center of the Asian karst region, characterized by underground drainage systems with sinkholes and caves, and it holds a rich biodiversity in its karst habitats that is a high priority for conservation. Future intensified surveys combined with molecular and acoustic data, especially in previously unexplored areas, will likely continue revealing new species of this cryptic genus, and each discovery sharpens the scientific case for protecting the montane streams on which these animals depend.

Subject of Research: Description of a new megophryid frog species, Brachytarsophrys wui, from Mt. Foding National Nature Reserve in Guizhou, China, based on morphological and molecular evidence

Article Title: Morphological and molecular data reveal one new species of the genus Brachytarsophrys Tian & Hu, 1983 ( Anura , Megophryidae ) from Guizhou, China

Article References: Lyu, J.-C., Zhou, S.-L., Zhang, T.-B., Fang, Y., Ran, S.-Y., Dai, L.-L., Jiang, X.-K., Long, H.-W., & Yuan, G. (2026). Morphological and molecular data reveal one new species of the genus Brachytarsophrys Tian & Hu, 1983 (Anura, Megophryidae) from Guizhou, China. Zoosystematics and Evolution, 102(1), 71-85. https://doi.org/10.3897/zse.102.161437

Image Credits: AI Generated

DOI: 10.3897/zse.102.161437

Keywords: Brachytarsophrys wui, new species, amphibian, frog, Megophryidae, Guizhou, China, herpetology, taxonomy, biodiversity, Morphological, molecular