Photographic composite by Nathan Lujan, courtesy the Field Museum
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The Ancistrus leoni is one of six new bristlenose catfish species discovered by Lesley de Souza and her collaborators. It's named after her late colleague, Oscar Léon Mata.

Photographic composite by Nathan Lujan, courtesy the Field Museum

New species of spiky-faced catfish discovered

The scientists say that the discovery of these six new species is more ammunition for protecting Brazil’s forests.

Lesley de Souza never expected the species of catfish she was searching for to be served up to her on a platter—but then she got to dinner.

The Field Museum conservation biologist spent her days dragging her net through the dark muck in the Amazon and Orinoco Basins in northeastern South America, searching for bristlenose catfish, and arrived back at camp near dusk.

Local guides working with de Souza (then a Ph.D. student) and her advisor, Jonathan Armbruster, an ichthyologist at Auburn University, prepared local fare for the researchers, including capybara, caiman, and yes, even sucker-mouthed, armored catfish.

“I had all sorts of things. You just eat what you’re served,” de Souza says. Which is how she realized that she likely ate some of her research subjects.

In their 15 years exploring the Orinoco Basin and surrounding areas, de Souza and Armbruster discovered six new species of bristlenose catfish, which they describe in an article published February 6 in Zootaxa. (See pictures of an armored, wood-eating catfish discovered in the Amazon.)

Covered in tough body armor, the bristlenose catfish can also defend themselves with spines around their heads that they enlarge when threatened. De Souza quips that these battle-ready Ancistrus are like “fish superheroes” for their ability to transform.

“It’s the most comprehensive study of this group of catfish, which is a very challenging group to study. This work provides a great service for other researchers,” says Nathan Lujan, an ichthyologist at the American Museum of Natural History, who wasn’t involved in the study.

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BRISTLENOSE FAMILY

Catfish are one of the most diverse groups of fishes on Earth, and the new discovery puts the total number of Loricariidae (the family which includes bristlenose catfish) close to a thousand. In addition to their head spines, males also have large, bulbous tentacles around their mouths that researchers think mimic the appearance of larvae that they care for.

“It shows females that this guy can give me good kids,” de Souza says. (See pictures of bizarre freshwater fish.)

Besides the relative inaccessibility of her field sites, what made de Souza’s work to identify all of the bristlenose catfish in the Amazon and Orinoco Rivers challenging was the catfish themselves. As a group, bristlenose catfish are common in the Amazon, and locals regularly put them on the menu. But individuals of the same species can vary widely in size, shape, and color, while members of different species can appear nearly identical. Adding even more of a challenge was the fact that many of the reference samples in museums had been collected nearly a century before, and years in preservatives had discolored many of the catfish’s distinctive markings—a key feature de Souza uses to distinguish many species.

“It’s hard to do a study like this,” Lujan says. “When you have a bunch of fishes in a pile on the table, it’s hard to figure out where to draw the line” between one species and another.

NAMED FOR NOSTALGIA

Back in the lab, de Souza and co-authors Armbruster and Donald Taphorn pored over details of her specimens, confirming the existence of known species and identifying six others new to science. These new species not only allowed de Souza to clarify relationships between the different bristlenose catfish but also expand what researchers know about their biodiversity. Read about another spiny catfish that's also venomous.)

Because the region is increasingly under threat from gold mining, hydroelectric dams, unsustainable fishing, and agriculture, say Lujan and de Souza, the new species' discovery gives conservationists more ammunition to fight threats.

“You can’t prioritize conservation if you don’t know what’s there,” Lujan says.

It’s why de Souza named one species of catfish Ancistrus saudades, from the Portuguese word for melancholy and nostalgia, to describe how she feels about her homeland of Brazil experiencing so many changes to the Amazon Basin. (Read more: Brazil's new leader promised to exploit the Amazon—but can he?)

But the urgency also gives de Souza hope. “A fish being found only in one particular river could help keep a dam from being built. That’s what gets me excited."