China's smallest known wood frog first discovered in Zhejiang

A new species of wood frog, named Lessor Brown Frog, or Ji Lin Wa, has been discovered in East China's Zhejiang Province, the Xinhua News Agency reported on Saturday.

The research findings were published in the journal Asian Herpetological Research on November 29.

Liu Baoquan, the lead author and senior engineer at the Zhejiang Forest Resource Monitoring Center, told Xinhua that the new species is the smallest known species of wood frog in China. Adult male frogs of this kind have a body length of less than three centimeters, and the largest adult female specimen measures only 3.5 centimeters. The species has so far only been found in the Baishanzu Scenic Area of the Qianjiangyuan-Baishanzu National Forest Park in Zhejiang.

The discovery is a result of the field surveys conducted as part of the construction of Zhejiang's amphibian and reptile database. The research team made multiple trips to the Longquan area of the Baishanzu Scenic Area, conducting targeted field investigations in mountainous rice paddies. After comparing the frog's morphology with similar species and conducting genetic sequencing, the team confirmed it as a new species, which they named the Ji Lin Wa.

Wang Yufan, co-first author and the frog's primary discoverer, explained that the new species bears a striking resemblance to the local dominant species, the Zhenhai Brown Frog, particularly in terms of appearance and overlapping breeding periods. However, the new species is less than half its size, making it easy to mistaken for a juvenile Zhenhai Brown Frog. 

"We frequently collected these unusually small frogs in the same rice paddies, but we know they are not young Zhenhai Brown Frogs, as they typically do not enter the mountain rice paddies during the breeding season," Wang told Xinhua. "My professional intuition told me these small frogs must be something different."

The new species breeds in winter, laying eggs in mountainous rice paddies. Its most distinctive morphological feature is a dark brown spot behind its eyes, with an almost arc-shaped lower edge, and unusually small webbing on its hind legs.

Phylogenetic analyses indicate that the frog represents a highly differentiated lineage, occupying a basal position on the phylogenetic tree, and forms a sister group with frog species from East Asian islands. 

Liu noted that a healthy ecological environment is a key foundation for preserving biodiversity and the discovery of the new species further demonstrates Zhejiang's role and value in biodiversity conservation in East China, Xinhua reported.

The discovery was made through collaboration between the Zhejiang Forest Resource Monitoring Center, the Kunming Institute of Zoology at the Chinese Academy of Sciences, and research teams from Southwest University.