Tag: earthworm

Researchers have discovered a new genus and species of underground earthworm eel living beneath the Indo-Gangetic Plain in Bihar, northern India. The small, colourless creature, named Gangaichthys indonepalicus, is the first subterranean fish to be recorded from the Gangetic Basin.

Close-up of *Gangaichthys indonepalicus*. Image credit: Ishan Agarwal.

The research, published in ZooKeys, was carried out by an international team of scientists from the Thackeray Wildlife Foundation in Mumbai, India; Shivaji University in Kolhapur; the Shanghai Synchrotron Radiation Facility at the Chinese Academy of Sciences; and the Zoological Survey of India in Gopalpur-on-Sea.

The investigation began after a short video clip posted on TikTok in 2024 showed an unusual tiny fish emerging from a water borewell near the border between India and Nepal.

“The unique morphology of the fish in the video, and the fact that there are no known stygobitic fish known from the region, motivated us to track down the species to ascertain its identity.”
The Research Team

Securing physical samples required an intensive fieldwork effort in Bihar, where the scientists manually pumped thousands of litres of water from local handpumps.

“Procuring samples of this unusual fish was challenging. Identifying potential handpumps (borewells) and wells, and obtaining permission from their owners to extract water for the purpose of searching for the fish proved difficult. This became more intensive when we finally began manually pumping water.”
Akshay Khandekar, Thackeray Wildlife Foundation

Live and habitat photos Gangaichthys indonepalicus — Live and habitat photos *Gangaichthys indonepalicus*: NRC AA 9519, holotype, 40.6 mm SL: Dorso lateral view of: A. Full body; B. Head; C. Bore-well from which holotype and one (damaged) paratype was collected; D. Bore-well from where another damaged specimen was collected. Image credit: Akshay Khandekar et al., 2026.

The first specimen emerged after pumping approximately 2000 litres of water but sustained damage during the process and died immediately. The second and only intact specimen (later designated as the holotype of this species) was found from the same borewell after pumping an additional 500 litres of water.

*Gangaichthys indonepalicus* in a syringe. Image credit: Ishan Agarwal.

The newly described fish measures roughly four centimetres in length and features physical adaptations suited to life in total darkness, including reduced eyes covered by skin, an unpigmented translucent body, and an apparent absence of ribs.

Advanced micro-CT scanning and genetic analysis confirmed that it represents a completely distinct genus within the earthworm eel family Chaudhuriidae.

“Gangaichthys means fish of the Ganga. The Ganga or Ganges is one of the most important rivers in India, both as a source of fresh water, food and livelihood for millions of people; besides having an important role in the Hindu religion.

This is the first stygobitic fish from the Indo-Gangetic plains and from the Gangetic basin.”
Ishan Agarwal, Thackeray Wildlife Foundation

As for the naming of the species itself, Tejas Thackeray commented:

“As the species occurs on the border between India and Nepal we picked indonepalicus as the specific epithet, which reflects the distribution of the species.”

*Gangaichthys indonepalicus*. Image credit: Ishan Agarwal.

Agarwal also reflected on the broader context of the find and the challenges of studying subterranean habitats:

“India is an incredibly diverse country, spanning huge gradients in climate and topography and multiple biogeographic regions. However, there is a huge gap in knowledge, both Linnaean and Wallacean shortfalls, with many more species yet to be discovered.

This exciting discovery is in some ways symptomatic of general biodiversity research in India, though sampling subterranean habitats is especially challenging.”

Original source:

Khandekar A, Thackeray T, He Y, Mohapatra A, Agarwal I (2026) Gangaichthys indonepalicus, a new genus and species of miniature stygobitic earthworm eel (Synbranchiformes, Chaudhuriidae) from alluvial aquifers in the Indo-Gangetic Plain, Bihar, northern India. ZooKeys 1289: 185-202. https://doi.org/10.3897/zookeys.1289.188089

For more articles on zoology, visit the ZooKeys website and follow the journal on BlueSky and Facebook.

New earthworm family, named Kazimierzidae, has been established for a South African indigenous genus of 21 species. Although the circulatory system in the group has been regarded as exclusive upon their original description in 2006, their raising to a family status have only recently been confirmed by a research team from South Africa.

Scientists Mrs Thembeka Nxele, Dr Danuta Plisko (original discoverer of the genus Kazimierzus, now known as family Kazimierzidae), affiliated with Natal Museum (NMSA), Oliver Tendayi Zishiri, affiliated with University of KwaZulu-Natal, and Dr Taro Mwabvu, University of Mpumalanga, looked into the earthworm collection at the NMSA, as well as the type material and the available literature. Their study is published in the open access journal African Invertebrates.

When compared to the rest of the members in the family Microchaetidae, where the former genus had been placed, the studied earthworms show a number of distinct characters, including an “exclusive” circulatory system. In these species it is a simple single tube stretching along the whole body.

All 21 earthworm species, now members of the newly established family, can only be found in small areas restricted in the western and south-western Atlantic coast of South Africa. These locations have long been known for their endemic invertebrates and diverse flora.

In their paper, the authors note that it is actually the restricted range, and therefore the specific ecological requirements, that might have led these earthworms to become that different from other species. Their distribution and, hence, poor dispersal ability, are also the reason why the newly established group would be particularly vulnerable if the habitat is transformed.

“The species distribution of earthworms in Southern Africa is presently poorly known hence the urgency for extended study on earthworm diversity and their distribution patterns,” point out the scientists. “Extensive earthworm collection in the western Atlantic coast may bring more data on this and other taxa.”

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Original source:

Nxele TC, Plisko JD, Mwabvu T, Zishiri TO (2016) A new family Kazimierzidae for the genus Kazimierzus, earlier recorded to the composite Microchaetidae (Annelida, Oligochaeta). African Invertebrates 57(2): 111-117. doi: 10.3897/AfrInvertebr.57.10042