Guwahati: Fifteen species of rove beetles previously unknown to science have been discovered in Arunachal Pradesh, adding significantly to knowledge of insect diversity in the Eastern Himalayas.
The discovery was made by an Indo-German research team working across remote mountainous regions of the state. It takes the number of Stenus beetle species recorded from Arunachal Pradesh to 103, including 21 species newly recorded in India and 44 recorded in the state for the first time.
The findings were published in Linzer Biologische Beiträge in a research paper by German taxonomist Dr Volker Puthz titled “Steninae from Arunachal Pradesh, India”.
Several of the newly described species have been named after scientists and researchers associated with the project.
Stenus gogoii, S. dobiami and S. sonui honour RGU researchers Dr Hiren Gogoi, Dobiam Tagam and Sonu Singh, while S. oliver and S. tobias recognise German collaborators Prof Oliver Betz and Tobias Mainda of the Institute of Evolution and Ecology at the University of Tübingen.
The research collaboration began in 2021, when Betz, a rove beetle expert, approached Rajiv Gandhi University (RGU) to explore Arunachal Pradesh’s largely unexplored insect diversity.
The partnership was formalised through a Memorandum of Understanding between RGU and the University of Tübingen in May 2023, with support from the German Research Foundation and permissions from the National Biodiversity Authority and Arunachal Pradesh forest authorities.
Researchers conducted four field expeditions between December 2024 and March 2025, covering Pakke Kessang, West Kameng and Shi Yomi districts.
Working in forests, along streams and around waterfalls, the team used aspirators, sieves and sweep nets to collect specimens. Many of the tiny beetles, measuring between 1.9 and 6.5 mm, were found to be species never previously described.
The team also acknowledged the support of indigenous communities, particularly the Nyishi community of Pakke Kessang; the Sherdukpen and Bugun communities of the Eaglenest region in West Kameng; and the Memba and Adi communities of Shi Yomi.
Researchers said their support was indispensable, particularly for accessing remote habitats and documenting biodiversity.
Rove beetles are among the most diverse insect groups, with more than 63,000 known species worldwide. The genus Stenus is particularly diverse and is considered one of the largest animal genera on Earth.
Most Stenus species are tiny predators that inhabit damp environments such as stream margins, wetlands, bogs and moist leaf litter. They possess an unusually extendable, tongue-like mouthpart that can rapidly shoot out to capture small prey, including springtails and aphids.
Their specialised abdominal glands produce chemical compounds used for defence and protection against microbes, while some species also have adaptations that help them move across water.
The researchers believe Arunachal Pradesh may harbour many more undescribed species given its wide range of habitats and relatively limited insect surveys.
The discovery, they said, highlights the importance of sustained biodiversity exploration in the Eastern Himalayas and the potential of international scientific collaborations involving local universities and indigenous communities.
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