Expedition finds a 10-inch long millipede lost to science for 126 years

An expedition into Madagascar’s largest and most intact forest found 21 species that had been considered lost to science. A team studying the Makira Forest found three iridescent, nearly translucent species of fish and the first documented sighting of a roughly 10-inch-long millipede in 126 years. However, the dark brown millipede was likely never considered lost to local communities. 

The September 2023 expedition unfolded over several weeks as part of the Search for Lost Species, a long-term project by environmental nonprofit Re:Wild. Local guides and teams from Antananarivo University, American Bird Conservancy, The Peregrine Fund, Wildlife Conservation Society, and Biodiversity Inventory for Conservation (BINCO) also took part in the search. Different specialized teams scoured the forest for various invertebrates, amphibians, reptiles, birds, fish, and mammals that have not had a documented sighting in at 10 years or more, but not considered extinct by the IUCN Red List of Threatened Species. The full team has spent several months analyzing their data

[Related: Why small, scary, and ‘non-charismatic’ lost species are harder to rediscover.]

“In the past the Search for Lost Species has primarily looked for one or two species on each expedition, but there are now 4,300 species that we know of around the world that have not been documented in a decade or more,” Re:wild’s lost species officer and biologist Christina Biggs, said in a statement. “Madagascar is a biodiversity hotspot and Makira is an underexplored area within the country, so we decided to pilot a new model for lost species searches there. We convened a group of scientists to search for as many species as possible, and it proved successful.”

A big, brown, bug

Makira was home to several lost species of insects. Some of the bugs weren’t even on the initial list of lost species for the area, and were found by chance. The team’s entomologists found two different species of ant-like flower beetles that had been lost to science since 1958. The most unexpected rediscovered lost species was a large, dark brown millipede.

“I personally was most surprised and pleased by the fact that the giant millipede Spirostreptus sculptus, not uncommon in Makira Forest, appeared to be another lost species known only from the type specimen described in 1897,” BINCO entomologist Dmitry Telnov said in a statement. “The longest specimen of this species we observed in Makira was a really gigantic female measuring 27.5 centimeters [10.8 inches] long.” 

They also found a variety of spider species, including five jumping spiders that were considered lost to science since they hadn’t been documented, but not necessarily to locals. Seventeen of the spider species found on the trek are considered new to science. The jumping spider Tomocyrba decollata holds the record for the longest-lost spider. It hadn’t been documented since 1900, when it was first described by outside researchers. 

[Related: See the strange new species discovered near Chile—with the help of a deep-diving sea robot.]

A new species of zebra spider was the most unexpected buggy discovery. Previously, scientists did not think that zebra spiders lived in the rainforests of Madagascar. However, one of the team members saw a hanging egg sac in the entrance to a small cave.

“I immediately recognized them as something special,” Brogan Pett, director of the SpiDiverse working group at BINCO and doctoral candidate at the University of Exeter, said in a statement. “Pendulous egg sacs is one of the characteristics of the family of zebra spiders this new species belongs to. I crawled a short way inside the cave and saw a few adult spiders guarding egg sacs—they were quite large spiders and it was remarkable that they had gone unrecognized for so long.”

Three lost fish 

Initially, the team had a list of over 30 lost species that they hoped to find in Makira. This included three mammals, three fish, seven reptiles, 12 insects, and five spiders. They found all three fish species with the help of local fishers and guides. The Makira rainbow fish (Bedotia alveyi) and Ptychochromis makira which had been lost since 2003 and Rheocles sp–lost since 2006. Finding these fish was much more difficult than the team anticipated. 

“When we didn’t find anything during the first five days of the expedition it was very frustrating,” Antananarivo University fish biologist Tsilavina Ravelomanana said in a statement. “We sampled a small tributary of the Antainambalana River, then the main river, then upstream and then downstream, but we still didn’t find any fish. We changed our strategy and sent our local guides on a two-to-three-day hike away from our base camp to interview local fishermen.”  

Two of the expedition’s local guides–Melixon and Edmé–hiked around a steep waterfall and over mountains to villages from the expedition’s base camp along the Antainambalana River. The guides found the Makira rainbow fish–a common fish to local communities–after several days. They brought it back to base camp in a bucket of water. A few days later, they returned to the same villages with photos of the Rheocles sp. This fish is only a few inches long and has iridescent scales and red highlights on its body at the tips of its fins. Working with local fishermen, Melixon and Edmé found it.

[Related: ‘Lost Bird’ not seen in 20 years photographed for the first time.]

“We had already got two species, but we still needed to find one more,” Antananarivo University fish biologist Fetra Andriambelomanana said in a statement. “The guides told us that they thought the best place to find it would be in an area on our hike back out of the forest. They left ahead of us and we made plans to meet them when we left Makira.” 

They also found a fish named Ptychoromis makira. Biologists believe that this species may only live in one tiny area near Andaparaty, and is a rare species—even to local communities.

Among the species that the team could not find are the Masoala fork-marked lemur–not documented since 2004–and a large chameleon named Calumma vatososa–not documented since 2006.