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New copepod species highlights fragile biodiversity in Bermuda's caves

Bermuda's Walsingham cave system harbors a wide diversity of cave-dwelling animals not found anywhere else in the world. Now, one more joins their ranks as researchers at the University of Cambridge, the Bermuda Institute of Ocean Sciences and Senckenberg am Meer German Center for Marine Biodiversity Research report the discovery of a new copepod species.

The findings are in the journal ZooKeys.

Copepods are some of the most diverse of all crustaceans, found everywhere from freshwater ponds to the open ocean. These tiny organisms are some of the most abundant animals in the marine plankton, and an essential component of food webs worldwide. However, their huge diversity remains rather poorly known, particularly in challenging environments like subterranean caves.

The new Bermudian copepod, Tetragoniceps bermudensis, was first collected in 2016 by Sahar Khodami, Pedro Martinez Arbizu, and Leocadio Blanco-Bercial from the Bermuda Institute of Ocean Sciences and the Senckenberg am Meer German Center for Marine Biodiversity Research, who ventured into Roadside Cave through a narrow passageway in Bermuda's ancient limestone bedrock. However, it was only when researchers analyzed it in detail, in 2024, that T. bermudensis was confirmed to be an entirely new species.

Like other members of Bermuda's cave fauna, Tetragoniceps bermudensis—named after the country where it was discovered—might represent an ancient, early-diverging member of its evolutionary lineage, the research team says. Together with other ancient crustaceans inhabiting the island's caverns, it persisted in a secluded, delicate underground ecosystem relatively free from competitors and predators.

"The new species of copepod crustacean, Tetragoniceps bermudensis, is the first of its genus from Bermuda, as well as the first known cave-dwelling species of the genus anywhere in the world and only the second within its family, Tetragonicipitidae," says lead author Giovanni Mussini of the University of Cambridge's Department of Earth Sciences.

"This finding from Roadside Cave adds to the great diversity of endemic crustaceans (and other cave fauna) found in the island's network of limestone caves."

The team only found one female egg-bearing individual at Roadside Cave, a small cavern in Bermuda. It is hard to estimate just how rare the new species is based on a single specimen, but the finding "suggests a correspondingly limited area and a probable endemic status, consistent with the high degree of endemism typical of Bermuda's cave-dwelling fauna," write the researchers in their paper.

Roadside Cave, where the new species was found, may face threats from "urban development, vandalism, dumping, littering and pollution, and sediment disturbance due to unlawful access by humans and domesticated animals," which makes protecting this small creature all the more urgent. The researchers call for formal protection of the cave and for robust enforcement of existing measures to protect its precious fauna.

"The discovery of this species highlights that there remains a cryptic diversity of cave-dwelling species still to be discovered even in a densely populated island like Bermuda, whose hidden, underground biodiversity is all too often overlooked," Mussini concludes.