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‘Rainbow' creature with yellow eyes found in temporary pond. It's a new species
Near a river in the Democratic Republic of the Congo sat a temporary pond, doomed to dry up eventually. Inside swam a 'rainbow' creature with 'large' yellow eyes. Something about it caught the attention of passing scientists — and for good reason.
It turned out to be a new species.
Béla Nagy and a team of 'colleagues from the University of Lubumbashi' spent 7 years visiting rivers in southern Africa in search of 'seasonal' fish known as killifish, Nagy wrote in a study published June 30 in the peer-reviewed journal Ecology and Diversity.
Killifish are native to Africa and live in 'ephemeral wetlands' of the savanna, the study said. To survive the 'periodic drying out of their natural habitats,' killifish have short lifespans. They hatch, breed and bury their eggs during the wet season before dying off during the dry season in an annual cycle.
During their 2023 surveys, researchers found several colorful and unfamiliar-looking killifish, the study said. They took a closer look at the fish, analyzed their DNA and realized they'd discovered a new species: Nothobranchius iridescens, or the rainbow seasonal killifish.
Rainbow seasonal killifish are considered 'medium'-sized, reaching about 1.7 inches in length, the study said. Males have 'robust' bodies, while females are 'more slender.' Both have 'short' heads with cone-shaped teeth and 'large' yellow eyes.
Male and females of the new species vary in coloring. Females have dull 'light brown' bodies while males have vivid blue bodies.
Photos show some male rainbow seasonal killifish. Researchers said they named the new species after the ancient Greek word for 'rainbow' because of 'the colourful appearance of the males, containing different colours of the rainbow, such as yellow and red in the fins, reflective blue on the body slightly shifting hue depending on the angle of light.'
Rainbow seasonal killifish were found in 'ephemeral pools and marshes on floodplains associated with the Kafila river,' Nagy said. In one such pond, the water was less than 2 feet deep 'at its deepest point,' cloudy and 'partly overgrown with grass.'
So far, the new species has only been found at one site in the southern Democratic Republic of the Congo. The country is in central Africa and borders nine countries: Angola, Burundi, Central African Republic, the Republic of the Congo, Rwanda, South Sudan, Tanzania, Uganda and Zambia.
Researchers considered the new species to be endangered because of its limited distribution and proximity to 'human populations,' whose activity poses 'an important extinction risk.'
The new species was identified by its DNA, coloring, head shape, body proportions and other subtle physical features, the study said.
Nagy also discovered three more new species of seasonal killifish and one new species of lampeye fish.
