Genetic analysis identifies Chinese spiny frogs mislabelled as East Asian bullfrogs in online trade

A genetic identification study found that four frogs purchased from an online retailer on Taobao under the label “Hoplobatrachus chinensis” were actually Quasipaa spinosa, or Chinese spiny frogs. The species is classified as Vulnerable on the International Union for Conservation of Nature Red List and the Red List of Chinese Species. The case documents species misidentification in China’s online amphibian trade but does not establish whether the animals were wild-caught, captive-bred or traded illegally.

Amphibians are among the most threatened vertebrate groups globally, with more than 41% of species currently classified as threatened with extinction. Habitat destruction, climate change, emerging infectious diseases and unregulated exploitation contribute to their decline. Across Asia, exploitation for consumption, traditional medicine and the wildlife trade has been identified as a primary driver of amphibian population declines.

China has a long history of domestic and international amphibian trade, while the expansion of online commerce has changed how live animals are marketed and transported. Digital platforms such as Taobao and WeChat facilitate purchases without appropriate permits or scientific oversight, and amphibians are often listed under vague or incorrect trade names. Such mislabelling can undermine enforcement, distort records of species occurrences and trade volumes, and compromise conservation assessments and management decisions.

The four specimens were shipped as “ornamental amphibians” without a scientific name. Researchers photographed them after arrival and documented body colour, skin texture and limb proportions. The research was conducted under Institutional Animal Care and Use Committee approval number 2025028 from the ethics board of Nanjing Forestry University. Their snout–vent lengths were 95, 104, 101 and 97 mm.

For the genetic analysis, the researchers extracted genomic DNA from thigh muscle tissue. They amplified a 530-base-pair fragment of exon 1 of the nuclear tyrosinase gene, known as TYR, a marker used for identifying Asian dicroglossid frogs. After trimming and aligning the sequences with homologous records from the National Center for Biotechnology Information, the final dataset contained 572 base pairs from 51 sequences representing Q. spinosa and related species.

Phylogenetic relationships were estimated with Bayesian inference in MrBayes. The dataset was partitioned by codon position, and substitution models were selected with PartitionFinder. The Markov Chain Monte Carlo analysis used four chains over 10 million generations. Convergence checks found an average standard deviation of split frequencies below 0.05 and effective sample sizes above 200 for all parameters.

All four specimens produced high-quality TYR sequences that shared more than 99% identity with published Q. spinosa sequences. The Bayesian tree placed all four within the Q. spinosa clade with posterior probabilities greater than 0.99, supporting their identification as Chinese spiny frogs rather than H. chinensis. The analysis recovered seven well-supported clades corresponding to Fejervarya, Hoplobatrachus and five Quasipaa species.

Physical examination also supported the genetic result. Although the specimens had a general body shape similar to H. chinensis, they had relatively rough dorsal and lateral skin, chest tubercles with small round warts bearing tiny black spines, and pale-yellow ventral surfaces. Their throats were unmarked, while their limbs were either unmarked or had brown cloud-like spots. These traits are consistent with Q. spinosa, whose appearance overlaps with that of the widely farmed East Asian bullfrog.

The four-specimen case cannot establish the scale or origin of the trade, nor whether the misidentified frogs were legally traded, and the study did not test whether the commercial label was intentional. Nevertheless, the results show how visual identification can fail in commerce and why molecular verification may improve monitoring of traded amphibians. The authors propose integrating molecular diagnostics into customs inspections and online marketplace monitoring, expanding genetic reference libraries, and requiring clearer species labels. They also emphasize the livelihoods of communities traditionally involved in harvesting Q. spinosa and the need for public information on species identification and relevant wildlife-trade rules.

Subject of Research: Genetic identification of Quasipaa spinosa mislabelled as Hoplobatrachus chinensis in China’s online amphibian trade

Article Title: Hidden or inadvertent illegal amphibian trade? Genetic analyses reveal Quasipaa spinosa misidentified as Hoplobatrachus chinensis in the trade

Article References: Zhang, X., Borzée, A., Gill, S., & Othman, S. N. (2026). Hidden or inadvertent illegal amphibian trade? Genetic analyses reveal Quasipaa spinosa misidentified as Hoplobatrachus chinensis in the trade. Nature Conservation, 63, 247-257. https://doi.org/10.3897/natureconservation.63.183849

Image Credits: AI Generated

DOI: 10.3897/natureconservation.63.183849

Keywords: Quasipaa spinosa, Hoplobatrachus chinensis, amphibian trade, DNA barcoding, TYR gene, species misidentification, Taobao, wildlife commerce, biodiversity monitoring, Hidden, inadvertent, illegal