The primitive fishes, which scientists call “living fossils,” represent a new taxonomic family, a rare finding.
Researchers have discovered a new family of eel-like fish, named dragon snakeheads, which live in underground waters in southern India.
These primitive fish are a type of “living fossil” and may have diverged from their nearest relatives more than a hundred million years ago.
Discovering a new family of fish the taxonomic category above genus and species is very uncommon, says study leader Ralf Britz, an ichthyologist at Senckenberg Natural History Collections, part of the Museum of Zoology in Dresden, Germany.
Taxonomic families are often large and diverse; For example, the human family, Hominidae, includes chimpanzees, orangutans, and gorillas.
This family includes only two species, one of which is named the Gollum snakehead, after the subterranean Lord of the Rings character.
“We think this is the most exciting discovery in the fish world of the last decade,” says Britz, lead author of a study published recently in Scientific Reports.
These strange, long-bodied fish, which dwell in aquifers of porous rock, are rarely seen, only coming to the surface after flooding from heavy rains.
Britz says the family’s common name is fitting because “everyone who sees a photo of the fish is somehow reminded of a dragon.”
The area where the fish live, the Western Ghats of southern India, is a biodiversity hot spot. In all, scientists have discovered 10 species of subterranean fish in the aquifers there that provide water for millions of people.
An estimated six million wells draw from this underground reserve, Britz says. This has lowered the water table and could imperil some of the newfound obscure species that live there.
– Enigmatic species –
The saga began in early 2018, when researcher Rajeev Raghavan, a study co-author and fish researcher at Kerala University of Fisheries and Ocean Studies, spotted a post on Indian social media from a person who found and photographed an odd fish retrieved from their backyard well.
Raghavan sent the photo to Britz, who had “no idea what it was,” Britz says not the species, genus, or family. Britz travelled to India after Raghavan and other colleagues had collected more specimens, to scientifically describe the fish.
An initial study, published in Zootaxa in May 2019, identified the fish as a new species and genus, named Aenigmachanna gollum the Gollum snakehead.
Shortly thereafter, another researcher found a second species in that genus as well, based on a single specimen the Mahabali snakehead.
Another breakthrough came when Britz and others visited a farmer’s field north of Kochi, a town in Kerala. There, late at night, they found Gollum snakeheads surfacing into a flooded rice paddy.
But when Britz and his colleagues performed further research on the anatomy and genetics of these fishes, he found they belong in a new family entirely.
His genetic analysis shows they may have diverged from their nearest relatives, snakeheads in the family Channidae, before Africa and India separated and spread apart 120 million years ago, Britz says.
There are more than 50 species of Channidae snakeheads, which live in streams and lakes throughout Asia and Africa.
