An integrated study on the biodiversity and ecology of mayflies (Insecta: Ephemeroptera) in Arunachal Pradesh, India

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.