Kryptoglanis shajii is a small, pinkie-sized subterranean catfish that sees the light of day only rarely, when it turns up in springs, wells and flooded rice paddies in the Western Ghats mountain region of Kerala, India.

The Mystery Fish

It was first described as a new species of catfish in 2011. Soon after, John Lundberg, one of the world’s leading authorities on catfishes, started taking a closer look at several specimens.

“The more we looked at the skeleton, the stranger it got,” says Lundberg, emeritus curator of ichthyology at the Academy of Natural Sciences of Drexel University and emeritus professor in the College of Arts and Sciences. “The characteristics of this animal are just so different that we have a hard time fitting it into the family tree of catfishes,” he adds.

His team’s study describing the detailed bone structure of Kryptoglanis was published in the 2014 issue of the Proceedings of the Academy of Natural Sciences of Philadelphia.

From the outside, Kryptoglanis doesn’t look particularly unusual for a catfish. But when Lundberg and his colleagues looked at its bones using digital radiography and high-definition CT scans, they found some surprises.

Kryptoglanis was missing several bony elements — a characteristic fairly common for subterranean fish. There were also changes in the shapes of certain bones. Numerous individual bones were modified in the face, giving the fish a compressed front end with a jutting lower jaw.

Why Kryptoglanis is so different, and what its closest relatives are, remains a mystery. This fish is just one of many unresolved branches on the catfish family tree, in a section where even DNA evidence has thus far proven unhelpful.
Subterranean species like Kryptoglanis tend to have dramatically different DNA sequences from one another and from their open-water relatives, making it difficult to identify their evolutionary histories.

“It continues to be a puzzle,” Lundberg says.

Odd_Fish

This elusive little subterranean fish has a bone structure all its own.