The study describes a new species of Polyrhachis, or spiny ant, named Polyrhachis garbhangaensis sp. nov., from the state of Assam, northeastern India. This species was collected and identified during field sampling in the Garbhanga Reserve Forest, near the city of Guwahati in Assam. It represents a third Indian species of the P. mucronata species group in the subgenus Myrmhopla. Polyrhachis Smith, 1857 is a genus of ants, found widely across the Old-World tropics, with significant diversity across Southeast Asia. The discovery and characterisation of this species clearly indicate the need to revise the classification key of the genus Polyrhachis. As a step towards this, we present an updated key to the species of the mucronata group of Polyrhachis (Myrmhopla), including the new species. This finding contributes to a deeper understanding of the taxonomic diversity of Polyrhachis and highlights the unexpected importance of urban and fragmented forest areas in sustaining tropical ant biodiversity.
