Guwahati: On a misty April morning in 2021, deep within the subtropical forests of Arunachal Pradesh’s Siang Valley, a team of researchers carefully turned over a damp stone. What they found beneath it would rewrite history—a tiny, velvety creature with stubby legs and a soft, segmented body. It was Typhloperipatus williamsoni, a species lost to science for 111 years.
The researchers—Surya Narayanan, D.R. Priyadarsanan, A.P. Ranjith, R. Sahanashree, and Aravind Neelavar—from the Ashoka Trust for Research in Ecology and the Environment (ATREE) and Yenepoya Research Centre, were retracing the historic ‘Abor Expedition’ of 1911–1912. During this expedition, British zoologist Stanley Kemp first described the species, which then vanished, leaving behind only its scientific name in old expedition records. For over a century, it was presumed extinct.
Velvet worms (Onychophora) like T. williamsoni are evolutionary relics, dating back over 500 million years. These “living fossils” are known for their unique hunting technique—they shoot jets of sticky slime to trap their prey. Soft-bodied, nocturnal, and highly elusive, they thrive in damp forest microhabitats, making them particularly difficult to find.
The breakthrough came in April 2021 when the team discovered a single individual under a small stone near Kalek, a village just 3 km from the species’ original type locality at Rotung. A year later, in May 2023, they made a second discovery—another T. williamsoni in the forests near Yingku, approximately 45 km away. Scientists believe the lack of recent records could be attributed to the species’ elusive nature and the inaccessibility of its habitat.
Typhloperipatus williamsoni was first collected during the ‘Abor Expedition’ (also known as the Siang Valley or Siang Expedition) by Stanley Kemp, then superintendent of the Indian Museum, Calcutta. In December 1911, Kemp and his team found it near Rotung and the Dihang River gorge in what is now Arunachal Pradesh. In 1913, he published a preliminary note describing a potential new genus from the North-Eastern Frontier Agency (now Arunachal Pradesh). In 1914, Kemp formally described the new genus and species based on specimens collected during the expedition.
The rediscovery of this long-lost species offers crucial insights into the ancient biogeography of velvet worms. Using molecular analysis, the research team extracted DNA and sequenced three mitochondrial genes (12S, 16S, and COI). The results revealed that T. williamsoni is closely related to Southeast Asia’s Eoperipatus, suggesting an ancient evolutionary link between India and Southeast Asia. This discovery refines theories about how species migrated and evolved when the Indian subcontinent was still drifting before merging with Asia.
“Several new species of flora and fauna have been described in this region over the last decade. However, the whereabouts of T. williamsoni remained unknown until now. This is likely due to a lack of awareness about this fascinating species, which somehow failed to attract the attention of researchers,” say scientists associated with the study. “It is also important to note that large areas of the Siang Valley have remained largely inaccessible to researchers for a long time. It is intriguing that this species was originally described during the Siang Expedition of 1911–1912 and was rediscovered nearly a century later during a follow-up expedition along the same route.”
The rediscovery of Typhloperipatus williamsoni after more than a century highlights the importance of biodiversity surveys in the Siang Valley. This study provides the first molecular data for the species, establishing its phylogenetic placement and addressing gaps in the evolutionary history of Asian peripatids. However, habitat loss due to agriculture, jhum cultivation, and deforestation poses significant threats to its survival.
“Conservation efforts, including habitat protection and monitoring, are critical to safeguarding this unique species. Future research should prioritize phylogenomic analyses and broader sampling to uncover hidden biodiversity in this underexplored region of the Eastern Himalayas,” the scientists emphasize.
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