Meeting (and describing) a Patagonian seahorse species

Guest blog by Dr. Diego C. Luzzatto, CONICET- National Scientific and Technical Research Council, Argentina. iSeahorse National Seahorse Expert.

This story begins many years ago, when I was a child. I remember taking a slow and dusty train to the mountains in Bariloche from Buenos Aires that stopped in every town of Patagonia. One of those stops in San Antonio Oeste. A couple of children climbing onto the train to sell seashells and dry seahorses to fellow passengers caught my attention. A few minutes later, the train continued on its journey to the next stop and I forgot about those children and their seahorses for almost 20 years.

It is difficult to understand and explain how on these lands, visited and studied by so many dedicated naturalists such as Charles Darwin and Alcides D´Orbigny that there were no records of seahorses inhabiting Patagonia. Only few seahorses, caught by old expeditions, had been deposited at the Argentinian National Museum of Natural History. Recently, ichthyologists admitted to their presence in the Argentine Sea, but, no one had studied them and no one knew what species they were. All the available local fish records contained confusing and inaccurate identifications (European or invalid species) and were recorded without any geographical information.

This fact did not escape the curiosity of Dr. Gabriela Piacentino, an ichthyologist and former curator of the MACN. She often had lunch with us in the lab next door – the lab where I started my career as a marine scientist. Gabriela was particularly interested in seahorses and in my sampling techniques that consisted of trawling shallow sandy bottoms monthly. We were studying the giant free egg capsules of a Volutid gastropod its unique mode of reproduction. I listened to her but I was confident that I had never caught a seahorse within my samples and I felt that my studies would not help in her research. Soon thereafter “magic” happened and a female seahorse appeared in my samples.

After this it was very difficult for me to focus on my PhD work, I was captivated by this unexpected finding. I was very motivated by a wrong conviction that it should be a new species based on ecological facts. Now, I know more about the mechanism of the dispersal of seahorses and how species can exhibit large geographical ranges. However, at the time, my thoughts were that it should be considered a different species because adult seahorses are known to be “almost sessile” organisms and it was found isolated in Patagonia miles away from any other known population. Fortunately, Gabriela has a strong background in taxonomy and asked for reference material from several Museums around the world. After much work on the specimen and comparing it with the voucher specimens from other museums she started considering that the seahorses found in the Argentinian Sea may constitute a new species, but not on the basis of my erroneous hypothesis.

Nonetheless, more specimens were needed to reach to a final conclusion. Suddenly, I remembered that train, the children and the dry seahorses! A few weeks later, Gabriela and I ventured to San Antonio Oeste. We visited the local fishing dock and found, at its craft fair, dry seahorses being sold as curious souvenirs. We asked the merchants how those seahorses were caught and they offered to take us there. Using just a mask and snorkel we discovered a very shallow place with a wonderful habitat that was full of seahorses. We collected a few specimens and went on to describe a new species Hippocampus patagonicus in 2004.

Fifteen years later, I am still engaged with these incredible organisms, generating information, mostly to preserve them and their delicate environment. Sadly, the precise place where I saw seahorses for the very first time is now overfished and the seahorses are hard to find. However, not everything is lost, places nearby look healthy and full of life. The threats are there but it is a rewarding challenge to work towards preserving Hippocampus patagonicus and their habitat.


Learn more about H. patagonicus
Wei, J., Estalles, M., Pollom, R. & Luzzatto, D. 2017. Hippocampus patagonicus. The IUCN Red List of Threatened Species 2017: e.T195100A54909767.

Piacentino, G. L., & Luzzatto, D. C. (2004). Hippocampus patagonicus sp. nov., nuevo caballito de mar para la Argentina (Pisces, Syngnathiformes). Revista del Museo Argentino de Ciencias Naturales, 6, 339-349.