Guwahati: Scientists exploring the forested hills of Nagaland have discovered two new species of lace-sheet-weaver spiders, shedding fresh light on the rich but still poorly explored biodiversity of Northeast India.
Researchers from the Zoological Survey of India (ZSI) identified the new species — Psechrus ntu and Psechrus phenshunyu — during a pre-monsoon faunal expedition in Nagaland’s Peren and Tseminyu districts. The findings have been published in the international journal Zootaxa.
The discovery also marks the first recorded presence of Psechrus himalayanus in Northeast India, significantly extending the species’ known range beyond its previously documented Himalayan distribution.
Named after the villages of Ntu and Phenshunyu, where they were discovered, the newly described spiders belong to the genus Psechrus, known for constructing large horizontal sheet-like webs in humid forest habitats.
Researchers said the findings further reinforce the ecological importance of the Indo-Burma biodiversity hotspot, of which Northeast India forms a crucial part.
The study was conducted by arachnologists Puthoor Pattammal Sudhin, Shouvik Mali and Souvik Sen.
One of the most intriguing observations during the survey involved an unusual behavioural interaction. A male Psechrus himalayanus was found sharing the same web with a female Psechrus phenshunyu — a rare case of heterospecific cohabitation that researchers say could complicate species identification during taxonomic studies and may point to previously undocumented behavioural interactions among these spiders.
The spiders were primarily found in shaded forest areas, rocky crevices and roadside cuttings, where they built sheet webs extending into narrow retreats beneath rocks and tree roots. Scientists noted that their camouflage and retreat-building behaviour make them extremely difficult to detect during field surveys.
Researchers believe the fragmented distribution of Psechrus spiders in India may reflect limited scientific exploration rather than actual rarity. Until recently, only a handful of species from the genus had been documented in the country, suggesting that many more could remain undiscovered in the remote landscapes of the Northeast.
In a parallel development, ZSI scientists have also completed the first comprehensive taxonomic revision of Indian whip scorpions, or thelyphonids, in more than a century. Commonly known as “vinegaroons”, these ancient arachnids spray a vinegar-like acid as a defence mechanism instead of venom.
The whip scorpion study redescribed four of India’s five known species and mapped their distribution, contributing to global understanding of a rare arachnid group with only 138 known species worldwide.
“These works represent a bridge between historical taxonomy and modern conservation needs, providing a baseline for groups that have been overlooked for decades,” said Souvik Sen, co-author of both studies.
Dhriti Banerjee said the institution is increasingly focusing on documenting obscure faunal groups and uncovering the “white holes” of Indian biodiversity that remain scientifically unexplored.
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