India, Nov. 7 -- In the quiet folds of Arunachal Pradesh's Siang Valley, where clouds drift low over forests of oak and rhododendron, a group of villagers and researchers have made discoveries that deepen the mystery of India's eastern Himalayas.

During recent biodiversity surveys in Simong village, Upper Siang district, six butterfly species never before recorded in India were documented. The findings, published in Entomon Journal, reveal a rare ecological bridge between the Brahmaputra River in Tibet - known there as the Yarlung Tsangpo - and the forests on its southern bank in Arunachal Pradesh.

Among the six are species as lyrical as their colours: the Litin Onyx (Horaga takanamii), Tibetan Junglequeen (Stichophthalma neumogeni renq...