The Entomological Society of Iran Journal of Insect Biodiversity and Systematics 2423-8112 12 3 2026 09 01 An integrated study on the biodiversity and ecology of mayflies (Insecta: Ephemeroptera) in Arunachal Pradesh, India 491 502 28611 10.48311/jibs.12.03.491 EN Muthukatturaja Marimuthu Miscellaneous Insect Order Section, Zoological Survey of India, Prani Vigyan Bhawan, M- Block, New Alipore, Kolkata–700053, West Bengal, India. 0000-0001-5796-0211 Thangavel Kubendran Miscellaneous Insect Order Section, Zoological Survey of India, Prani Vigyan Bhawan, 535, M- Block, New Alipore, Kolkata–700053, West Bengal, India. 0000-0003-2117-9938 Malaisamy Vasanth Southern Regional Centre, Zoological Survey of India, Santhome High Road, Chennai 600 028, Tamil Nadu, India. Basak Saheli Miscellaneous Insect Order Section, Zoological Survey of India, Prani Vigyan Bhawan, 535, M- Block, New Alipore, Kolkata–700053, West Bengal, India. 0009-0001-6507-2932 Kumarapuram Apadodharanan Subramanian Southern Regional Centre, Zoological Survey of India, Santhome High Road, Chennai 600 028, Tamil Nadu, India. 0000-0003-0872-9771 Journal Article 2026 01 28 The Indian Eastern Himalaya (Arunachal Pradesh) remains poorly explored for the diversity and ecology of mayflies (Ephemeroptera). The present study provides a comprehensive assessment of mayfly diversity, community structure, and species-environment relationships across 15 selected streams in Arunachal Pradesh. A total of 2,014 individuals belonging to 46 species, 25 genera, and seven families were recorded from the region. Baetidae was the dominant family, followed by Heptageniidae, whereas Caenidae and Vietnamellidae were the least represented. Diversity indices revealed considerable spatial variation, with the highest Shannon diversity, richness, and evenness observed in mid-elevation, fast-flowing streams, and the lowest values recorded at the sites with fewer individuals. Canonical Correspondence Analysis (CCA) exhibited that environmental variables such as pH, stream width, elevation, water current, canopy cover, and temperature influenced species distribution. https://jibs.modares.ac.ir/article_28611_fea42d70f2e3905853625e0e9762120f.pdf