- Researchers have described a new trapdoor spider species, Tigidia singhal, from the semi-arid grasslands of the Deccan Plateau. It belongs to an ancient group of mygalomorph spiders that spend most of their lives in burrows.
- The discovery marks the first record of the genus Tigidia from semi-arid open natural ecosystems, expanding its known range beyond forests.
- Researchers say more biodiversity surveys are needed to explore these overlooked ecosystems, where many more undescribed invertebrate species are likely to occur.
What began as a routine vegetation monitoring survey in Maharashtra’s semi-arid grasslands took an unexpected turn when researchers overturned a rock and stumbled upon a silk-lined burrow underneath. They recognised it as the burrow of a trapdoor spider — an ancient group of spiders, many species of which construct doors of silk and soil to conceal their burrow openings and ambush passing prey.
The team dug through the soil, following the burrow to its end where a female trapdoor spider of the genus Tigidia lay in a bulb-shaped chamber. A detailed examination of this specimen, collected in November 2025 near Nandeshwar Mahadev Temple in Ahilyanagar, Maharashtra, confirmed it as a new-to-science species. Researchers named it Tigidia singhal in their study published in the journal Arachnology, bringing the number of Tigidia species in India to eight.
Until now, species of this genus were known from peninsular India’s tropical evergreen and deciduous forests, particularly the Western and Eastern Ghats. T. singhal is the first record of this genus from a semi-arid open natural ecosystem, significantly expanding its known range.
“The species inhabits rocky hilltop grasslands of the Deccan Plateau, an ecosystem often overlooked despite supporting remarkable biodiversity,” wrote study authors Rishikesh Tripathi and Prasad Bolde in an email to Mongabay-India. “Finding a previously unknown trapdoor spider here highlights how little we still know about the biodiversity of these open natural ecosystems,” they added.
An ancient lineage
Trapdoor spiders are long-living, sedentary spiders that spend most of their lives in burrows, rarely leaving except to search for a mate, explained Tripathi and Bolde. Tripathi, the study’s lead author, is a Postdoctoral Research Associate at the Ashoka Trust for Research in Ecology and the Environment (ATREE) while Bolde is a Project Associate at the Wildlife Institute of India. Abi Tamim Vanak, Director of ATREE’s Centre for Policy Design, also co-authored the study.
The doors of silk, soil, moss and leaves that many species construct to camouflage their burrows give this group its name. “This adaptation has great advantages for the spider, providing protection against desiccation and predators and enabling efficient prey capture,” said arachnologist and herpetologist Zeeshan A. Mirza, a Research Associate at Mizoram University who was not associated with the study. But this camouflage also makes them difficult to find.
Trapdoor spiders belong to the infraorder Mygalomorphae which also includes tarantulas and funnel-web spiders. “[Mygalomorphs] are among the least-studied spiders because they are mostly burrow-dwelling and difficult to find in routine surveys,” said Mirza, adding that they are often large and considered primitive.
The genus Tigidia falls within the family Barychelidae (brush-footed spiders) — one of India’s nine mygalomorph families. According to the authors, spiders of the genus Tigidia occur only in Madagascar, Mauritius and India. “Such a disjunct distribution has long attracted interest because it is consistent with ancient geological connections associated with the breakup of the Gondwanan supercontinent. Every new species therefore contributes valuable information for understanding the evolutionary history and biogeography of these ancient trapdoor spiders,” they said.
Calling this an “exciting” discovery, Mirza added that the Gondwanan links make these spiders important relics that need to be conserved. “The diversity of these spiders is far from well known, and the new discovery from the Deccan is not surprising, as these regions have been barely surveyed for them,” he said. Mirza, who has previously described several Tigidia species, added that he has seen images and specimens from peninsular India indicating there are many yet to be described.
A burrowing spider
The collected specimen was a 15-millimetre-long female with black legs covered in greyish bristle-like hairs, and a lighter abdomen with chevron-shaped markings. Researchers identified its genus based on external characteristics before conducting a detailed morphological analysis and comparing the specimen’s features with all known Tigidia species. “The unique shape and arrangement of the spermathecae (female reproductive structures), along with a combination of other morphological characters, confirmed that it represented a species new to science,” noted Tripathi and Bolde.
So far, they have only found this species around the site where it was first recorded, suggesting a restricted distribution. Despite multiple revisits, the team is yet to come across a male. They did, however, find a female guarding an egg sac in June this year, indicating breeding likely begins with early pre-monsoon showers around May, continuing into June. The team is rearing 17-18 juveniles in the lab that have already emerged from the egg sac.
Most burrows researchers observed were lined with silk throughout, had two openings, and were usually located at the edges of rocks where the soil retained more moisture and provided structural support. During hot summer months, the moist soil underneath rocks “likely helps maintain suitable microclimatic conditions inside the burrow,” they explained.
These burrows were 4-10 centimetres deep, extending through the soil but changing direction if they encountered bedrock.
Trapdoor spider burrows aerate soil, maintain soil structure and provide microhabitats for other organisms. Highly-sensitive to habitat disturbances, these spiders also serve as ecological indicators, with their presence suggesting a healthy ecosystem and rich soil biodiversity.
“In many ways, if large mammals like tigers symbolise the ecological integrity of forests, ancient mygalomorph spiders such as Tigidia can serve as equally important flagship species for India’s grasslands and other open natural ecosystems,” said Tripathi and Bolde.
Overlooked ecosystems
The discovery of T. singhal also highlights the need for biodiversity surveys in India’s open natural ecosystems, large tracts of which have been misclassified as ‘wastelands’ — a practice that traces back to the colonial era.
Despite harbouring unique species such as the blackbuck and Indian wolf, these landscapes remain overlooked and underexplored compared to forests, particularly for invertebrates. Mirza noted that funding remains a hurdle when documenting the biodiversity of “non-charismatic taxa or so-called wastelands.”
Sparsely-vegetated grasslands, such as the one where T. singhal occurs, are often considered ‘degraded’ or ‘barren’ and face immense human-induced pressures, some of which the researchers observed firsthand. These ranged from direct land-use changes and soil extraction to tourism-generated plastic waste and stone quarrying that destroys the rocky microhabitats where these spiders build their burrows. “Since this species appears to have a very restricted distribution and depends on specific rocky grassland habitats, these disturbances could pose significant threats to its survival,” they added.
Currently, this species’ males remain unknown, while the spider’s breeding biology, life history, population status and distribution also require further study.
“Discoveries such as this demonstrate that these ecosystems harbour unique and highly specialised species found nowhere else. This information can help inform conservation planning, habitat management, and policy decisions by recognising grasslands as biodiversity-rich natural ecosystems rather than wastelands,” said the authors.
Banner image: A new trapdoor spider species, Tigidia singhal, from the Deccan Plateau. Image by Prasad Bolde.
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