A spider that does not build webs but is a robust and agile hunter nonetheless has been discovered in the Sunderbans.

The finding marks the first recorded instance of the genus Piratula in India, a group of wolf spiders predominantly found across Asia, with limited distribution in Europe and North America.

Researchers from the Calcutta-headquartered Zoological Survey of India (ZSI) have announced the discovery of the species on Sagar Island in the Sunderbans, around 100km from Calcutta, underscoring the region’s significant yet underexplored
biodiversity.

The species, Piratula acuminata, belongs to the family Lycosidae, commonly known as wolf spiders. Unlike web-building spiders, these predators are ground-dwelling and ambush their prey. They feed mainly on small invertebrates, predominantly insects.

Souvik Sen, lead researcher from the ZSI, described the species as “a medium-sized spider, approximately 8-10 millimetres in length, characterised by its pale creamy white coloration interspersed with brown, chalk-white spots on its abdomen, and a pair of light brown stripes towards the rear.”

The research team, comprising Sen and Sudhin P.P. from ZSI Calcutta, along with Pradeep M. Sankaran from Sacred Heart College, Kochi, published their detailed scientific account in the latest issue of Zootaxa, a peer-reviewed scientific journal, on July 7 this year. The specimen was collected from Sagar Island in November 2019.

“The distinctive structural intricacies of its genitalia, specifically the acuminate (narrowing to a slender point) basal arm of the tegular apophysis (a specific part of a male spider’s pedipalp, which is a leg-like appendage near the mouth) in males and ovate spermatheca (shape of the spermatheca, a sperm storage organ found in many invertebrates) in females, were key to its identification as a novel species,” he said.

“The unique morphological features of this spider immediately indicated it was an undocumented species. We conducted extensive morphological analysis over several weeks to confirm our findings,” Sen said.

This discovery on Sagar Island, the largest island within the Sunderbans deltaic complex, reinforces the ecological richness of this Unesco World Heritage Site.

The island’s unique ecosystems, shaped by alluvial deposits from the Hooghly, include vital mudflats and estuarine waters supporting a diverse array of flora and fauna.

Dhriti Banerjee, director of the ZSI, said: “Every new species we discover is a testament to the incredible natural heritage of this region. It also serves as a stark reminder of how much we stand to lose if we don’t expedite our efforts to protect these habitats.”

The researchers emphasise the critical need for further studies to understand the ecological role of Piratula acuminata and its potential vulnerability to the increasing threats posed by climate change within the Sunderbans ecosystem.

This discovery highlights the ongoing importance of biodiversity exploration and dedicated conservation initiatives in this vital global hotspot.