A new discovery has added six butterfly species previously unrecorded in India, with one, the Litin Onyx, known only from Laos, representing a massive range extension into the Eastern Himalayas. This finding, based on a brief but intensive survey in the Simong Community Forest of Arunachal Pradesh, highlights a critical, yet poorly understood, link between Indian and Tibetan biodiversity.
The discovery was made by a team of researchers from the Ashoka Trust for Research in Ecology and the Environment (ATREE) and the local Litin Community Conservation Society. Using photographic evidence gathered over just seven days in June and July 2024 during a camera-trapping expedition in the Upper Siang district, the researchers confirmed the six new additions to the country’s butterfly fauna.
The new records strongly suggest that the Siang Valley, connected to Metok County in southeastern Tibet by the Brahmaputra River, plays a vital biogeographic role. Three of the newly documented species—the Tibetan Duke (Euthalia zhaxidunzhui), the Tibetan Sergeant (Athyma yui), and the Tibetan Junglequeen (Stichophthalma neumogeni renqingduojiei)—were previously reported only from Metok, Tibet. The presence of these species in Arunachal Pradesh confirms that their range extends across this international border. The Tibetan Junglequeen, a large and striking butterfly previously thought to be localised in Metok, was found to be surprisingly common in the Simong Forest, with an average of 20 individuals encountered daily, a fact that underscores the striking lack of prior systematic surveys in this region.
The most significant find is the Litin Onyx (Horaga takanamii), which extends its known range by over 1,200 kilometres from Laos. The other new additions include the Narrow banded Royal (Dacalana vui), previously known from northern Thailand and Vietnam and distinguishable by a narrow white band across both wings, and the Mountain Columbine (Stiboges elodinia), a species found across northern Thailand, Laos, Vietnam, and China.
The Siang Valley is a key part of the Eastern Himalayas, a region of immense biodiversity spanning a massive elevational gradient from 150 to 5,000 metres. This range supports a rich mosaic of habitats, from alluvial wet grasslands to tropical evergreen and mixed conifer forests. Despite this natural wealth, it remains one of the least explored regions and is increasingly threatened by localised pressures such as timber extraction and the looming large-scale threat of the proposed Siang Dam project. Researchers emphasise that strengthening community conservation efforts, such as those by the local Litin clan, alongside rigorous scientific documentation, is essential before this irreplaceable biodiversity is lost.
The full list of new additions to the Indian butterfly fauna includes:
- Litin Onyx (Horaga takanamii): Previously known only from Laos.
- Narrow banded Royal (Dacalana vui): Known from northern Thailand and northern Vietnam. This species is easily distinguished from other Indian Royals by a narrow white band across both wings.
- Tibetan Duke (Euthalia zhaxidunzhui): Previously known from Metok (Tibet) and North Myanmar.
- Tibetan Sergeant (Athyma yui): Known from southeastern Tibet, northern Myanmar, Thailand, Laos, and Vietnam.
- Tibetan Junglequeen (Stichophthalma neumogeni renqingduojiei): A subspecies previously known only from Metok.
- Mountain Columbine (Stiboges elodinia): Known from northern Thailand, Laos, Vietnam, and China.