Scientists of the Zoological Survey of India (ZSI) have discovered two new species of hoverflies, named Eristalinus sapphirinus and Eristalinus brunettii, from the Gangetic Plains of Bengal, marking the first addition to India's known Eristalinus fauna in more than a century.
The newly identified species were described in a study published in the European Journal of Taxonomy, ZSI said on Wednesday. The research was carried out by Bristi Roy, Oishik Kar and Jayita Sengupta of the Kolkata-based institution.
According to the study, the discovery expands the known diversity of the Eristalinus genus in India, with the last major contribution to the group's taxonomy dating back to 1923.
The researchers examined specimens collected from different districts of Bengal between 2022 and 2025 and used a combination of morphological analysis and mitochondrial COI DNA barcoding to establish that the specimens represented two previously unknown species.
Eristalinus sapphirinus was named after its metallic sapphire-blue coloration, while Eristalinus brunettii honours entomologist Enrico Adelelmo Brunetti for his contributions to the study of Indian flies.
Hoverflies, belonging to the Syrphidae family, are important pollinators and play a key ecological role. Adult hoverflies visit flowers and assist in pollination, while their larvae help decompose organic matter in aquatic habitats.
ZSI Director Dr Dhriti Banerjee said the discovery highlighted the presence of undocumented biodiversity even in heavily human-modified landscapes such as the Gangetic Plains.
Dr Atanu Naskar, Officer-in-Charge of the Diptera Section at ZSI, said the identification of hoverfly species can be challenging because of their similar appearance, and the study combined traditional taxonomy with DNA barcoding and modern species-delimitation methods to confirm the distinct status of the two species.
Lead researcher Bristi Roy said the findings underscored how much insect biodiversity remains undocumented, including in everyday landscapes outside protected areas.
