Helcyra hemina Hewitson, 1864 (Nymphalidae: Limenitidini),

commonly known as the White Emperor, was described by W.C. Hewitson from “ India ” without recording the precise locality. The known distribution range of H. hemina also includes Thailand, Laos and Vietnam (Inayoshi 2025). This rare butterfly is notable for its striking white and black wing patterns and is primarily associated with temperate forest habitats at altitudes 1000–1500 m. The White Emperor has been recorded in Sikkim, north West Bengal and Bhutan, and is also known from hills south of the Brahmaputra River in Meghalaya and Nagaland (Van Gasse 2018). Van Gasse (2018) describes H. hemina as rare in the Himalayas, with its distribution confined to regions up to 1500 m in elevation, and also predicts the occurrence of the White Emperor in Arunachal Pradesh due to the region’s ecological similarity to the butterfly’s known habitats. The present note confirms the presence of H. hemina in Arunachal Pradesh, thus filling a critical gap in its known distribution and contributing to the growing knowledge of the butterfly diversity in the northeastern Himalayas.

Field work was conducted in the temperate forest habitats of Arunachal Pradesh in 2022–2024. The specific observation of Helcyra hemina occurred on 18.ix.2022, near Gandhigram village (27.14999°N 97.01721°E) at an elevation of ca. 1067 m. The habitat was characterized by dense shrubs, tree canopies and a rich diversity of wild flowers. The butterflies were photographed using a digital camera. No specimens were collected due to relevant wildlife conservation legislation (Ministry of Law and Justice 2022). Helcyra hemina (Figs 1, 2) was observed at several sites around Gandhigram. In total, three individuals of this species were documented. External morphological characteristics were consistent with those given by Hewitson (1864) and Kehimkar (2016):

Upperside: Forewings mainly white with prominent black markings near apex and along margins; hindwings with black spots and narrow black outer margins. Underside: Lilac-white with faint brown lines and reddish brown arcs on hindwings.

The documentation of Helcyra hemina is consistent with previous studies (Variya et al. 2021; Upadhaya et al. 2023; Gogoi et al. 2024), which emphasize the rich butterfly biodiversity in Arunachal Pradesh. The temperate forest habitats of Arunachal Pradesh, characterized by a rich diversity of flora and stable microclimatic conditions, provide an ideal environment for H. hemina. However, the rarity of observations highlights the species’ vulnerability, the potential adverse impact of habitat degradation in the region and the need for targeted conservation efforts to protect temperate forest habitats and the unique butterfly species they support.