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A team of international scientists have discovered and described a new type of ‘killifish’ that is endemic to a Kenyan forest. But it is already critically endangered and may become extinct soon.
Killifish are oviparous or egg-laying fish that are mainly found in the fresh or brackish waters of the Americas, southern Europe, much of Africa, the Middle East and Asia. There are around 1,270 species of killifish.
The fish was discovered in the ephemeral swamps of the Gongoni Forest in south-eastern coastal Kenya by the team of scientists who conducted expeditions in 2017 and 2018.
It was given the scientific name Nothobranchius sylvaticus, from the Latin meaning “pertaining to the forest". It is also the first known endemic killifish to persist in a forest.
“The team performed both a principal component analysis, based on the physical traits of the fish, as well as DNA sequencing, to confirm that it is indeed a new species. A dated phylogenetic analysis, the most comprehensive for the genus, indicated that the N. sylvaticus lineage diverged from its sister species about 7.09 million years ago,” a statement by South Africa’s Stellenbosch University noted.
The findings indicate that the Gongoni Forest itself is more than 7.09 million years old. At only about 8.2 square kilometres, it is a combination of savannah interspersed with forest patches that stretches. It is thus a typical example of the East African Mosaic that stretches from as far south as Pondoland in South Africa to as far north as southern coastal Somalia.
The scientists have been DNA sequencing fish groups since 2015, along with dating of rocks from key landforms in East Africa. They aim to reconstruct the tectonic development of Central Africa over the past 20 million years.
“For the scientists, the discovery of N. sylvaticus was one more example of the congruence between evolutionary events in the genus Nothobranchius with paleo-drainage dynamics, which were driven by the tectonic events that formed the East-African River Valley System,” the statement noted.
It added that due to the new species’ severely restricted habitat in an ancient forest, it also faces a high conservation risk.
The article titled “The description of a critically endangered new species of seasonal killifish, Nothobranchius sylvaticus (Cyprinodontiformes: Nothobranchiidae), a relict species from an East African forest refugium in south-eastern Kenya" was published in Zootaxa with authors Prof. Dirk Bellstedt (SU), Béla Nagy (France), Dr P. de Wet van der Merwe (SU), Dr Fenton P.D. Cotterill (The Wilderness Project—Great Spine of Africa, Wild Bird Trust), Quentin Luke (East African Herbarium, National Museums of Kenya), and Dr Brian R. Watters (Canada).