Lost and Found: How one piece of evidence led to the rediscovery of a crab not seen for 225 years | endangered species

tEliminating rare species thought to be extinct is never easy, but when Pierre A Mvogo Ndongo traveled to Sierra Leone In January 2021 to search for the “missing” species of crabs living on Earth, the feeling of looking for a needle in a haystack was particularly strong given the size of the “haystack”. For one species, the Afzelius crab (Afrithelphusa afzelii)last seen in 1796, the only clue is a label on a specimen that simply says: “Sierra Leone”.

The Mvogo Ndongo expedition was primarily looking for the land-dwelling Sierra Leone crab in rainbow colors Afrithelphusa leonensisLost to science for 65 years and thought possibly extinct – a species at wildlife charity Re:wild’s 25 “Most Wanted Lost Species” existing. He also hoped – but never expected – to find an Afzelius crab (Afrithelphusa afzelii).

Both types are terrestrial crabs that live in burrows on the rainforest floor. Most freshwater crabs in Africa It lives in rivers, streams and lakes,” says Mvugu Ndongo, a lecturer at the Institute of Fisheries and Aquatic Sciences at the University of Douala in Cameroon.

The species of interest belongs to a unique family of African tropical plants that includes individuals that can breathe air, which has enabled them to conquer more murky habitats in the rainforest, often far from permanent water sources… [They] They are very colorful compared to their river-dwelling cousins, and can climb trees, live in rock crevices, burrow in swamps, or make burrows on the forest floor,” he says.

He adds that Sierra Leone, Guinea and Liberia are the only countries in Africa where these crabs are found, and there are only five known species.

For three weeks, working alongside communities in Sierra Leone’s northern, southern and southeastern districts, Mvugu Ndongo found nothing but false leads and frustration.

While many scientific discoveries (and rediscoveries) have been aided by the careful and intense observations of other scientists who have gone before, that was not the case here.

Afrithelphusa afzelii It hadn’t been seen in 225 years, and the only information about literally where to look for it was on the specimen’s label as “Sierra Leone” — a very undefined area indeed,” says Mvugu Ndongo. “We deduced that it must have been collected within walking distance of Freetown, So we began our studies in the woods in that vicinity. But this was still very vague.”

The team asked locals if they had seen any crabs living on land away from rivers and streams until they met someone who could help. “We got lucky – a man took us to his farm at the edge of the forest where the species was rediscovered after extensive research,” he says.

The day after finding the Afzelius crab, Mvogo Ndongo traveled to the forests of Sugar Loaf Mountain, south of Freetown. With time running out due to the impending Covid-19 lockdown, he searched around Lake Guma, heeding a local’s advice.

Deep in the jungle, he finally finds a Sierra Leone crab. The crabs lived in burrows so deep that Mvugu Ndongo and his team had to carefully excavate them with picks and machetes, before scouring the soil from the crabs to reveal colorful crustaceans – the first living specimens seen since 1955.

Sierra Leone Crab (Afrithelphusa leonensis)
Sierra Leone crab (Afrithelphusa leonensis), and is one of the 25 most wanted species in Re:wild. Photography: Pierre A. Mfugo Ndongo / Re: Wild

Besides the rediscovered Sierra Leone crab and Afzelius crab, two new freshwater crab species have also been found. However, the crabs’ habitats are now threatened by the destruction of forests for agriculture and firewood.

“These discoveries are bittersweet because the joy of discovering lost species mixes with the realization that they, while not extinct, are on the brink of extinction, and that urgent conservation interventions will be required to protect these species in the long term,” says Neil Cumberledge, professor in the Department of Biology. at Northern Michigan University, who collaborated with Mvugu Ndongo on the expedition.

Scientists now know crabs are out there, and it is hoped that they will be protected.

“The new data generated by the mission will allow us to reassess the Red List status of each of these species that are potentially ‘endangered’, that is, on the brink of extinction,” says Cumberledge. “The next step is to develop a species action plan and implement preventative measures in the field with Sierra Leone environmentalists to save these species from extinction.”

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