Guwahati: In the shaded undergrowth of Garbhanga Reserve Forest — where the city of Guwahati slowly gives way to streams, bamboo thickets and leaf litter — scientists have uncovered a species previously unknown to science.
Meet Polyrhachis garbhangaensis sp. nov., now christened the “Assamese Spiny Ant” — a discovery that quietly elevates Garbhanga’s ecological status and reinforces Assam’s reputation as a biodiversity hotspot.
The study, published in Asian Myrmecology (2026), was led by researchers from the National Institute of Advanced Studies (NIAS), Bengaluru — Ankita Sharma, Paul Antony Mangaly, Suraj Kumar Singha Deo, Sangavi D, and Anindya Sinha — in collaboration with the Coexistence Studies Group at the Trans-Disciplinary University of Health Sciences and Technology.
The new species belongs to the Polyrhachis mucronata species group under the subgenus Myrmhopla. Remarkably, it is only the third Indian species recorded in this group, highlighting the rarity and scientific importance of the discovery.
India currently hosts 71 species of the genus Polyrhachis, with Assam alone accounting for 21 of them, making the state one of the country’s richest regions for spiny ant diversity.
The ant was collected in August 2023 using pitfall traps placed along a stream transect inside Garbhanga Reserve Forest — a 117 sq km green belt forming part of Guwahati’s southern forest landscape and contiguous with Rani Reserve Forest.
The discovery emerged from a broader research project examining how rapid urbanisation is reshaping ant and spider diversity in South Guwahati. That such a significant find surfaced in a forest fragment bordering a fast-growing city adds further weight to long-standing conservation concerns.
At just 5.6 mm in length, the holotype worker may be tiny, but it carries striking diagnostic features. It has a bright yellowish-orange abdomen, unlike its black-bodied relatives, moderately long and curved petiolar spines, and a shiny yet distinctly sculptured head. These subtle but definitive traits clearly set it apart from its closest Indian counterparts.
Adding another layer of intrigue, researchers also recorded an ant-mimicking spider (Peng sp., family Corinnidae) in the same habitat.
Such spiders often evolve to resemble dominant ant species, hinting that the newly discovered ant may play a significant ecological role in its microhabitat. The finding opens new questions about predator–prey dynamics and species interactions within Guwahati’s urban-edge forests.
Beyond adding a new species to science, the study also updates the identification key for Indian members of the Polyrhachis mucronata group — an important contribution for future taxonomic and ecological research.
More importantly, the discovery underscores a powerful message: urban forest fragments are not ecological leftovers — they are living laboratories of evolution and resilience.
As Guwahati continues to expand, the Assamese Spiny Ant stands as a reminder that even forests at the city’s doorstep can hold species still waiting to be named.
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