Polish Scientists Discover New Crustacean Species in Norway, Challenging Past Research

Hydrobiologists from the University of Szczecin, working with international researchers from Norway, Germany, and Austria, have identified a new species of crustacean. The newly discovered species, named Eurytemora nilsseni, inhabits water bodies on islands along the Skagerrak coast. This finding revises earlier scientific understanding, as the researchers have effectively corrected a classification error made over 120 years ago.

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The differences are very small. They can concern individual bristles, the number of spines on structures that are on the order of 100-200 micrometers. So, these are very subtle details.

The Szczecin-based scientists have been studying Eurytemora velox, a type of copepod found throughout Europe, for the past six years. Dr. Łukasz Sługocki, a professor at the University of Szczecin and the project's leader, explained that by analyzing populations from various water bodies, they observed that individuals from small Norwegian coastal reservoirs were larger and possessed a distinct fifth pair of legs. "The differences are very small," Prof. Sługocki noted. "They can concern individual bristles, the number of spines on structures that are on the order of 100-200 micrometers. So, these are very subtle details."

Genetic and statistical analyses ultimately confirmed that the populations represented two distinct species, not one. The new species was named Eurytemora nilsseni in honor of the late Norwegian scientist Jens Petter Nilsen, who participated in the international research. The study combined traditional methods of examining organism structure with modern genetic techniques, a process known as integrative taxonomy, which allowed for the detection of micro-differences in the crustaceans' morphology.

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Sars did not have the analytical tools that we have today. We measured several dozen individuals from each population, used statistical tools, ordination methods, but also genetic methods, which ultimately explained that in reality, these are two species, not one.

Copepods of the Eurytemora genus have been known to science since the 19th century. In 1853, Swedish zoologist Wilhelm Lilljeborg described Eurytemora velox. Half a century later, Norwegian zoologist Georg Ossian Sars described and illustrated very similar copepods from islands off the Skagerrak coast, also identifying them as Eurytemora velox. However, the research by the Szczecin scientists has shown that Sars had observed a separate species. "Sars did not have the analytical tools that we have today," Prof. Sługocki stated, highlighting the advancements that enabled this new discovery.

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The fifth pair of legs proved crucial in the research.