Scientists identify new brown frog species in Chongqing

Researchers in China have described Rana shii, a new medium-sized brown frog from Chongqing that forms its own evolutionary lineage and is closely related to Rana maershanensis. The finding expands the known range of this little-studied Rana lineage into southwestern China and suggests more cryptic amphibian diversity may still be undiscovered.

Why it matters: - The discovery adds a new amphibian species to Chongqing’s fauna and extends the known range of the Rana maershanensis lineage into southwestern China. - The species was found in montane wetland habitat, which can be hard to survey and may still hold overlooked frog diversity. - The finding could help sharpen biodiversity baselines and guide conservation planning in the Daba Mountains.

What happened: - Researchers described Rana shii sp. nov., a medium-sized brown frog from Chongqing, China. - The species was published in Asian Herpetological Research on 04 June 2026. - The study was led by researchers from Southwest University, with colleagues from Slippery Rock University and the Chongqing Yintiaoling National Nature Reserve Administration Center. - The team collected eight adult frogs and one egg clutch during 2025 surveys in Chongqing Yintiaoling National Nature Reserve and Hongchiba National Forest Park, Wuxi County. - The species was named from morphological and molecular evidence. - The original paper was assigned DOI 10.3724/ahr.2095-0357.2026.0016.

The details: - Rana shii was recovered as an independent clade with strong support: Bayesian posterior probability of 1 and bootstrap support of 100. - The new frog is the sister species of Rana maershanensis, with Bayesian posterior probability of 0.98 and bootstrap support of 96. - The lineage sits outside the four recognized Chinese Rana groups. - Mean genetic distance between Rana shii and Rana maershanensis was 7.51% for the mitochondrial COI gene and 2.29% for 16S rRNA. - Mean intraspecific distances were 0.78% for COI and 0.3% for 16S rRNA. - Adult males measured 52.7–58.3 mm in snout-vent length, and females measured 54.8–62.2 mm. - The species lacks a vocal sac. - The dorsolateral folds are well developed, straight or slightly curved outward at the temporal region, and do not connect to the posterior corner of the eye. - Toe tips lack lateroventral grooves. - When stretched, the hindlimbs bring the tibiotarsal articulation to or beyond the snout tip. - The tympanum is slightly larger than half the eye diameter. - Vomerine teeth occur in two oblique rows between the choanae. - The tongue is deeply notched. - Nuptial pads are divided into two patches without nuptial spines. - Toe length follows the order IV > V > III > II > I. - Males lack abdominal lineae masculinae. - The holotype, an adult male labeled SWU 0015390, was collected at 2,265 meters in Chongqing Yintiaoling National Nature Reserve. - Field observations recorded breeding in ponds in early April. - The eggs had black animal poles and grayish-white vegetal poles.

Between the lines: - Rana maershanensis has remained hard to place in Chinese frog taxonomy, and previous studies produced unstable results. - Some analyses linked R. maershanensis to the Rana japonica group, but later genomic work did not confirm that relationship. - The new species and R. maershanensis likely form a two-species clade, but the broader evolutionary relationships still need stronger genomic sampling, especially nuclear genes. - The Chongqing population is geographically distant from R. maershanensis in central-southern China, which fits an allopatric speciation pattern. - The authors say more cryptic diversity may remain hidden in this lineage.

What's next: - Future surveys should target montane wetlands and combine morphology, call data, and multilocus genetics. - Broader taxonomic sampling and nuclear markers are still needed to resolve the lineage’s placement. - Targeted monitoring may help reserve managers protect habitat and improve amphibian surveys in the Daba Mountains. - The authors say follow-up work could improve detection of cryptic frog species in poorly surveyed wetlands.

The bottom line: - Rana shii shows that even well-studied regions in China can still yield new vertebrate species, especially in isolated mountain habitats.