New seahorse species discovered off Tamil Nadu coast by Kerala scientists

Originally, the Indian Ocean seahorses were thought to belong to a different species found in the Pacific Ocean. However, the scientists found that the new species was found to be a different one.

“Hippocampus histrix was originally described from Japan in 1856. Previous Indian specimens have been recorded under this name in museums. But when we did the morphology and genetic studies, we came to know that it was different…..there was more than a 6-7 per cent genetic difference between the two groups,” Kannan Shalu, the paper’s first author, told The Indian Express.

Shalu said the two species have similar external features, which made it difficult for earlier collectors to distinguish Hippocampus amandavincentae from Hippocampus histrix at first glance.

When the original version of the research was submitted for peer review, it was not accepted as only two specimens of Hippocampus amandavicentae seahorses were found so far, and hence their findings required more evidence.

“More specimens of seahorse were sourced from Japan for comparison, and samples from the Indian Ocean kept in museums were also checked,” Shalu said.

Finally, the researchers established that Hippocampus histrix, described in 1856 and long believed to occur from the Red Sea to parts of the Pacific, is primarily a Pacific Ocean species. The newly identified Hippocampus amandavincentae, meanwhile, is native to the Indian Ocean, while Jayakar’s seahorse (Hippocampus jayakari) is the species found in the Red Sea.

According to Rajeev Raghavan, another member of the research team, bycatch has also contributed to the discovery of several other new species, including species from the deep sea.

The research team also included Graham Short, Ghosh Ramvilas and Kutty Ranjeet. Their findings were published in Zootaxa in a paper titled A new species of spiny seahorse, Hippocampus amandavincentae, with redescription of H. histrix and H. jayakari.

According to the researchers, Hippocampus amandavincentae is also found in a coral reef habitat off the Kerala coast near Lakshadweep. Seahorses are generally associated with shallow marine habitats, including coral reefs and seagrass beds.

The discovery could also have implications for the conservation status of the species. Kannan Shalu said Hippocampus histrix is currently listed as ‘Vulnerable’ on the IUCN Red List. However, since Indian Ocean populations have now been identified as a separate species, Hippocampus amandavincentae will require a fresh assessment, she said.

Some of the threats facing seahorses in the Indian Ocean include fishing for traditional Chinese medicine and the aquarium trade —  notably, both of these would be illegal in Indian waters as all seahorse species are listed under the Wildlife Protection Act.