In the spring of 2025, I found a damselfly in Spain that belonged to a species that had never been found in Europe before: Pseudagrion sublacteum. A report on this observation has been submitted to Odonatologica and is expected to be published in the December issue. I wrote about it on my website:
“Pseudagrion sublacteum (Cherry-eye Sprite). I found a single male of this African species on a rock in a river. It was the first Pseudagrion ever found in Europe! So not only is the species new to the European list, so is the genus!”
An observant visitor to this website pointed out to me that the genus Pseudagrion is not entirely new to Europe; various finds of Pseudagrion microcephalum have been documented throughout Europe. And this visitor was right! And yet there is an important difference between the findings of P. microcephalum and those of P. sublacteum. How so? Let’s take a look at both species, where they occur and how they ended up here.
Pseudagrion sublacteum – Cherry-eye Sprite
P. sublacteum is widespread in sub-Saharan Africa, with small relict populations in Morocco and the Levant. These relict populations date back to a time when northern Africa was much wetter than it is today. The distance between the Moroccan populations and the site in Spain is approximately 300 kilometers as the crow flies, a distance that a damselfly could cover under ideal conditions (e.g., favorable wind direction).
In Morocco, the species is confined to fast-flowing lowland rivers in semi-arid areas, with grassy banks supporting bushes and reeds. This is very similar to the habitat at the location where the species was seen in Spain, which is the Río Guadiaro at El Colmenar. With the trend of European summers getting hotter and dryer on average, the potential amount of habitat for this and other African species only increases.
Two things stand out: the damselfly in Spain most likely arrived in Europe from Morocco under its own steam and has also found a habitat there that is equivalent to the optimal living environment in Africa. It cannot be ruled out that the species will establish in Europe in the near future.
Pseudagrion microcephalum – Blue Sprite
P. microcephalum also has a large distribution area, which, unlike that of P. sublacteum, is entirely located in Asia and Australia. The westernmost natural habitat is in India, approximately 4,000 kilometers from Europe. Within this distribution area, the species is not very particular about its habitat: Blue Sprites are found in both stagnant and flowing water, in rice fields and other artificial waters, and the water quality does not need to be very high. Between the Asian range and Europe lies not only a great distance but also a whole range of landscape types that are impossible or very difficult for a damselfly to cross: high mountains, deserts, dry steppes. The chance of this species ending up in Europe on its own is nil. Yet there have been a couple dozen sightings in Europe at least, all of which could be directly linked to the international trade of aquarium plants.
Accidental import of dragonflies via the aquarium trade
Import of non-native odonata species through the aquarium trade happens on a regular basis but often unseen initially as it’s the dragonfly’s or damselfly’s eggs that end up in aquariums in the first place. These eggs are transported there, invisible inside aquatic plants that function as Trojan horses. The plants are cultivated in tropical countries, most notably Singapore, Indonesia and Thailand. Female dragonflies and damselflies oviposit in the aquatic plants while they grow. This explains why the list of dragonfly species that appear in aquariums mainly contains Asian species. Once imported to a European aquarium, it often takes weeks to months before the eggs hatch and tiny nymphs suddenly inhabit the tank. Aquarium enthusiasts usually consider these nymphs unwanted and fear their presence, as the predatory nymphs can wreak havoc among young fish and freshwater shrimps alike and are often hard to discern between the dense aquarium vegetation. Once found, odonate nymphs are often killed and removed from the aquarium.
As said, discoveries of exotic dragonfly or damselfly nymphs in aquariums are quite common. Curious to find out if it would be hard to get my hands on any exotic species, I posted a call for live odonate nymphs in a Dutch freshwater shrimp enthusiast facebook group back in 2021. Within a few days I received a message from an aquarist, who had found a live damselfly nymph in the filter of his freshwater shrimp tank and kept it apart for me. I picked up the nymph a day later, on a Saturday, to rear it in an aquarium at my home. Being full-grown at reception, it emerged at my home next Tuesday. In this case, the species was Ischnura senegalensis, Tropical Bluetail, a common species in Asia and Africa. The latest addition of shop-bought plants to the finder’s aquarium had been about two months earlier.
Ecological threats of accidental introduction
So far, we haven’t seen any cases of exotic odonata species being introduced to European habitats and managing to establish. Other aquarium species (some fish, crayfish, plants) however managed to establish after release or escape from aquariums and some of them form a major ecological hazard. These invasive species can threaten entire freshwater habitats. It’s of utmost importance that exotic species are never released in the wild. To be sure, the Tropical Bluetail shown above was collected together with her exuviae after emergence, even though this species has already shown it won’t survive in our climate. Notably, a small population of the species has managed to survive in a tropical greenhouse in the Blijdorp Zoo, Rotterdam between 2013 and 2019 but eventually disappeared and they were never found outside the greenhouse.
Conclusion
It was indeed incorrect that this was the first time a Pseudagrion had ever been found in Europe. The correct statement would be: the observation of a male P. sublacteum in Spain in the spring of 2025 was the first known case of a damselfly of the genus Pseudagrion that can be assumed to have arrived in Europe unassisted.
The sightings of P. microcephalum all involved individuals that turned up in aquariums. The species only managed to reach Europe thanks to the transport of aquarium plants, i.e. as an unintentional side effect of human activity. This puts the species in the company of dozens of other tropical species that have turned up in European aquariums.
Further reading
For further reading about accidental import via aquarium trade, I recommend looking up the following article, which includes a list of exotic species found in Europe as well as a lot of background information:
Laister G., Lehmann G. & Martens A. 2014. Exotic Odonata in Europe. Odonatologica 43(1/2) 2014: 125-135 (this article is available on ResearchGate: https://www.researchgate.net/publication/263850234_Exotic_Odonata_in_Europe)
Thanks
I want to say thanks to Sr. Miguel Conesa from Málaga for pointing out to me that Pseudagrion microcephalum has been found in Europe, it gave me the idea for this write-up.