Meet the Scientist Who Discovered a New Genus of Curious Catfish Hiding in Colombia’s Most Endangered River
Museum ichthyologist Cristhian Conde-Saldaña uses evolutionary genetics to study freshwater fishes and document at-risk biodiversity
Colombia’s Magdalena-Cauca Basin stretches almost 949 miles, connecting a remarkable diversity of landscapes. Starting at high elevations in the Andean mountaintops, it flows down to the coast of the Caribbean Sea. Branching off into many winding rivers, such as the Cauca and the San Jorge, the basin is home to over 238 species of freshwater fishes.
The basin’s epicenter holds nearly 80% of Colombia’s human population, many of whom rely on the social and economic services of the rivers to live. However, human-caused disturbances such as pollution and habitat encroachment have drastically reduced the region’s biodiversity.
These challenges could doom species scientists have not even described yet, which is a major problem according to Cristhian Camilo Conde Saldaña, the current Collette Postdoctoral Fellow in the Division of Fishes at the National Museum of Natural History. Conde-Saldaña believes people cannot protect what they don’t understand, and studying evolutionary history is what ultimately leads to conservation.
This week, Conde-Saldaña and colleagues described a new group of catfish from the Magdalena-Cauca Basin in the Zoological Journal of the Linnean Society. The new genus, known as Magdalenichthys, holds four previously undescribed species that have been swimming right under the noses of over 48 million people living in the region.
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How did freshwater fishes initially captivate your interest as a researcher?
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As a child, I grew up along the Magdalena-Cauca Basin in the Tolima Department. I have fond memories of traveling with my family to the rivers and exploring the clear water. I became obsessed with catching all sorts of fish, hoping to see a different one each time.
The beauty of my home country has always drawn me back to the Magdalena. Even when I lived in Brazil developing my postgraduate studies, I remained involved in collaborations with colleagues to advance efforts in documenting and mapping Colombia's freshwater fish diversity.
I soon recognized there was a huge lack of information on evolutionary relationships of catfish species in the basin. Even in such a populous, well-researched area, there was an opportunity to help place species in their rightful position within the tree of life.
What made this discovery so unexpected and how was it ‘hidden in plain sight?’
With 80% of Colombia’s population living along the Magdalena, the basin has become one of the most scientifically sampled regions in the country. Species in the basin are highly specialized due to the wide range of ecosystems present along the rivers — from the cold and high-altitude Andes to the humid Caribbean lowlands. This variety of environments provides an exceptional opportunity to study biodiversity and evolution.
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What resources aided you in discovering this new catfish genus?
All materials used in the study came from field expeditions carried out across different regions of the Magdalena-Cauca Basin. Specimens and tissue samples were then deposited in several biological collections in Colombia, including the Universidad del Tolima, the Instituto Humboldt and the Universidad de Antioquia.
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The first step was to find where the catfish fit into the evolutionary tree available for its family. This was done by analyzing specimens’ Ultraconserved elements (UCEs), or genetic data common among diverse species. This allowed us to understand the evolutionary relationships within the group of fish we sampled and see how they have changed over time. We also conducted detailed comparisons of external morphology, or specific structural features, and osteology, or specific bone structures, with other genera in the family and different populations of the potential new genus.
By integrating comparative morphology with additional genetic data based on DNA barcoding — a method that uses mitochondrial DNA to help categorize species — we reached a remarkable conclusion: we had discovered a new genus containing four species previously unknown to science!
However, we did not confirm our findings right away as some uncertainties remained. We also consulted the vast fish collection held at the National Museum of Natural History. Coincidentally, among these collections were decades-old specimens — including the original material used to describe Heptapterus panamensis, a similar-looking catfish species from Panama. At first glance, the resemblance was undeniable. To rule out any connections completely, we performed detailed morphological measurements and counts. We also compared DNA sequences for this species, available in a global database known as the BOLD system. The results were clear: we confirmed that we had indeed discovered four new species native to the Magdalena-Cauca Basin.
The Smithsonian’s fish collection played a key role in this discovery, highlighting the fundamental importance of museum collections for biodiversity research.
Why is it important to document the biodiversity of freshwater fishes in the Magdalena-Cauca Basin and elsewhere in the world?
Documenting biodiversity is a crucial first step in understanding factors that stabilize an environment. Unless you can record every species in an ecosystem, no matter how small, you will never be able to get the full picture. Understanding how diversity originates and how landscapes have changed over millions of years gives us the groundwork we need to form active conservation plans.
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As for freshwater fishes in the Magdalena, they are an important resource for the people of Colombia. The decline of even the smallest fish species could disrupt the region’s equilibrium, affecting the people whose livelihoods are linked to the rise and fall of the ecosystem. The work that my colleagues and I do not only helps conserve biodiversity, but hopefully has a direct, positive impact on human society.
What do you hope people will learn from this discovery?
I think this is an important opportunity for people to learn about the unique biodiversity of Colombia. Even in places that are heavily populated and threatened, we were able to find new life. Although biodiversity is declining around the world, it is our responsibility to take care of what is left and continue investigating solutions.
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I have always enjoyed working with nature and asking questions about evolution. It fascinates me to learn how historical patterns heavily influence the diversification we observe today. Cataloging what we have now, and what once thrived in the past, is the best way for us to create a blueprint for conservation in the future.
Meet a SI-entist: The Smithsonian is so much more than its world-renowned exhibits and artifacts. It is a hub of scientific exploration for hundreds of researchers from around the world. Once a month, we’ll introduce you to a Smithsonian Institution scientist (or SI-entist) and the fascinating work they do behind the scenes at the National Museum of Natural History.
