Seahorse scientists have identified a new pygmy seahorse species in Sodwana Bay, South Africa, the first of its kind found in African waters and the Indian Ocean.
The Sodwana pygmy seahorse is the eighth pygmy seahorse to be described from the Indo-Pacific, the first confirmed record from the African continent and the Indian Ocean, and represents an extension of more than 8,000 km beyond the previously known range of pygmy seahorses from the Central and Western Indo-Pacific.
Like all pygmy seahorses, the new species is tiny, growing to just over 2 cm (about the size of a grain of rice) and has a honey-brown colour overlaid with a white netted pattern and a reddish tail. The scientific name of the Sodwana pygmy seahorse, Hippocampus nalu, means “here it is” in the local Xhosa and Zulu languages to highlight that the species was there all along until its discovery. The name also refers to the middle name of the person who discovered it and first brought the species to the attention of the researchers, Savannah Nalu Olivier.
The researchers collected two specimens at 14 meters depth from sandy flat reef in high current in Sodwana Bay, a popular scuba diving area within the iSimangaliso Wetland Park, and a World Heritage site located along the north coast of KwaZulu Natal province South Africa. The two individuals were loosely associating with small clumps of short algal turf using their prehensile tails, which were growing on sand-covered coral bedrock separated by sandy gullies around 2 meters wide. The current was so strong in the sandy gullies that the two seahorses were often observed being covered in sand, being swept from one location to another, and seemed to be having fun!
The researchers used a combination of DNA analysis and morphological characteristics to identify the new species. Hippocampus nalu differs from the closely related “Japan pig seahorse” (Hippocampus japapigu), recently described by the same research team in 2018, and other pygmy seahorses in the shape of the large spines located directly behind the head. Whereas the large spines are flat-tipped in most pygmy seahorse species, H. nalu possesses unusual double pointed large spines, which were revealed using micro computed tomography (CT).
Seven new species of pygmy seahorses have been officially described and named within the first two decades of the 21st century. The occurrence of a new species and first record of pygmy seahorse, H. nalu, in South Africa and the Indian Ocean is not unexpected but amazing nevertheless, since it’s been 50 years to date since the discovery of the first pygmy seahorse H. bargibanti in New Caledonia! The recent discovery of H. nalu in shallow coastal water highlights how little we still know about the marine life around Africa and about the extended seahorse family. The lack of research funding in this region of high biodiversity means there are many other species yet to be discovered in the western Indian Ocean.
Graham Short, Ichthyology Research Associate, Australian Museum Research Institute.
Short, G., Claassen L, Smith, R., Brauwer, M., & Hamilton, H., Stat M., Harasti, D. 2020. Hippocampus nalu, a new species of pygmy seahorse from South Africa, and the first record of a pygmy seahorse from the Indian Ocean (Teleostei, Syngnathidae) ZooKeys. DOI: 10.3897/zookeys.934.50924.
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