Rare aquatic beetle found for first time in Sweden

The leaf beetle (Macroplea pubipennis) is an aquatic beetle which has only been known to exist in Finland and China – until now! During the SEAmBOTH inventories of shallow coastal areas, it was finally found here on the northern swedish coast as well. In Finland it has been categorized as “vulnerable” and listed as a specie under strict protection in the Nature Conservation Degree.

2 beetles on an aquatic plant.
The M. pubipennis is covered in hair which may collect sediment and make the beetle look a bit fury and dirty. On the picture the male sits on top of the female, caught in the middle of a love act. Photo by Petra Pohjola, County Administrative Board of Norrbotten.

SEAmBOTH project partners and biologists in Finland have been talking about this beetle since we first met them at the start of the project. For us from Sweden it was totally new knowledge – an aquatic beetle which lives in shallow bays and has hairy legs – never heard of that before. Of course we got interested! As the marine environment and the coastal areas are very similar on either side of the Bothnian Bay, we were all convinced that the beetle must be living in Sweden as well. We just hadn’t searched enough for it.

2 small beetles with great camouflage on an aquatic plant.
The beetle grows to around 1 cm in length. They live their whole lives under water, mainly clinging to underwater plants, which they also feed from. Photo by Petra Pohjola, County Administrative Board of Norrbotten.

The beetle is not the easiest to find. We found it when we were snorkeling collecting data within the pilot areas of the project. It sits on plants, we’ve found it on perfoliated pondweed (Potamogeton perfoliatus) at depth down to one meter, but it has been reported to be living on other pondweeds as well as watermilfoils and horned pondweed.

4 pictures of the beetle on different plants.
The M. pubipennis needs vegetation to cling on to. Disturbances that destroy its habitats, such as dredging and coastal constructions may pose a threat to them. Photo by Petra Pohjola, County Administrative Board of Norrbotten.
Calm bay with reed bed and forest on the background.
Viewed from above water, a typical habitat for the beetle is a semi-sheltered shallow bay surrounded by reed. Photo by Kajsa Johansson, County Administrative Board of Norrbotten.

In Sweden researchers have been looking for the beetle along the coast north of Stockholm, but without finding any of them. We therefore feel extra proud to be hosting it here in the northern Bothnian Bay.  And it’s thanks to our collaboration with biologists in Finland, made possible by the SEAmBOTH project, that we had the opportunity to search for it and knowledge to find it.

For more information about Macroplea pubipennis, check out the:

HELCOM species information sheet,

Artdatabanken , with information in swedish

and SYKE with facts in finnish

Written by Linnea Bergdahl, County Administrative Board of Norrbotten.


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