Ukrainian zoologists, brothers Andriy and Serhiy Utevsky, have discovered a new species of Antarctic leeches. They found that the species initially migrated from Antarctica to the Arctic and then back to Antarctica, as reported by the National Antarctic Scientific Center of Ukraine.

In collaboration with foreign colleagues Alexander Beletsky and Joanna Cichocka from Poland, Mario Santoro from Italy, and Peter Trontel from Slovenia, the scientists investigated the distribution of fish parasites known as piscicolid leeches. Upon discovering the new species, the zoologists thoroughly studied its external and internal structure, as well as nuclear and mitochondrial genes.

"It turned out that the new leech belongs to the group called 'platybdelids.' They are common in the Arctic and adjacent waters of the Atlantic and Pacific Oceans. It's like finding a polar bear in Antarctica!" noted Serhiy Utevsky.

During the study of how such an extraordinary geographical distribution could occur, quite unconventional facts were established.

"Phylogenetic analysis and reconstruction of ancestral ranges indicated that fish leeches originated in the seas around Antarctica. They then spread across the World Ocean, reached the Arctic, and penetrated freshwater bodies in the Northern Hemisphere. However, the ancestor of our species later returned from the north to the homeland of the ancestors of the entire family of fish leeches in Antarctica," explained the researchers.

Molecular analysis showed that the new species separated from its northern relatives approximately 1.76 million years ago during the Pleistocene, a period of significant cooling on Earth. It was during this epoch that it managed to cross the tropics.

"We have classified the new species into a new genus called Austroplatybdellina, which translates from Latin as 'southern platybdellin,' because this Antarctic leech belongs to the predominantly northern group of platybdellins," the researchers announced.

Andriy and Serhiy Utevsky

"The complete official name of the newly discovered species in our study is Austroplatybdellina prodiga," explained Serhiy Utevsky, where 'prodiga' means 'prodigal,' characterizing the species' unusual behavior.

The Utevsky brothers are renowned researchers of polar regions from V.N. Karazin Kharkiv National University. For many years, Sergiy has been studying leeches in Arctic regions, while Andriy focuses on Antarctic leeches (having spent a winter as part of the 8th Antarctic expedition and participating in numerous seasonal expeditions at the "Academic Vernadsky" station). Currently, they have made 19 new scientific discoveries of animal species.