First Record of Snail-Killing Sciomyzids (Diptera: Sciomyzidae) from the Andaman and Nicobar Islands, India, with the Report of Three <i>Sepedon</i> Species

The dipteran family Sciomyzidae, often referred to as marsh flies or snail-killing flies, is reported for the first time from the Andaman and Nicobar Islands, India. During surveys conducted in 2022 and 2023, three species belonging to the genus Sepedon were identified: Sepedon ferruginosa Wiedemann, 1824, Sepedon aenescens Wiedemann, 1830, and Sepedon plumbella Wiedemann, 1830. While S. ferruginosa and S. aenescens were documented in the Andaman Islands and the Great Nicobar Island, S. plumbella was only seen in the Great Nicobar Island. Sciomyzid species are known for their affinity for freshwater habitats, exhibiting malacophagous behavior by acting as predators or parasitoids of aquatic snails. Certain species have been investigated as potential biocontrol agents against molluscs, who often serve as vectors of parasitic diseases like schistosomiasis in humans and fascioliasis in livestock. This finding not only expands the known distribution record of the family but also highlights the need to document lesser known Diptera fauna from the archipelago, which is a unique biodiversity hotspot with a rare ecological setting and a wide array of insect fauna.