Non-native (= alien) species can be a problem for any country because of the potential threat they may pose to local biodiversity and ecosystems. In 2009 (the last time a proper inventory was conducted), a number of non-native species in England was in excess of 3,500 species. About 10-15% of these are considered invasive, i.e. capable of having a negative impact on the environment, economy or human health. There are 12,000 non-native species already established in Europe and about 2,000 alien species (54 indoors only) in Britain, and a further 10–12 become established annually.
One of the most famous examples of introduced insect species appears to be the Manchester Moth. This species was introduced to the UK (Salford) from California in 1829, collected once and described as a new species (Euclemensia woodiella) and then disappeared (see here).
Most alien species introduced to Britain are originally from Europe, but in recent decades Asia and temperate North America have become major contributors of British non-native fauna and flora. To date, at least 20 species of spider had established themselves in Britain.
In the summer of 2023, I was contacted by his colleague from Exeter University who reported an unknown jumping spider which was observed and caught at the Tremough campus in Penryn (near Falmouth), United Kingdom. Immatures and adult females were found on 29 April and 07 May 2023, adult males and females and immatures were also collected on 17 May 2023. Further summer survey showed that spiders were still present and could be discovered by beating shrubs and trees between 50cm and 2.5m above the ground. It seemed that this spider species is likely to have established a reproducing population, at least on the university campus.
A sample of two males and one female was sent to me, and on examination was found to contain an unknown species of Salticidae that is not native to either the UK or continental Europe. Further study revealed that it belongs to an undescribed species of the Caribbean genus Anasaitis Bryant, 1850 (see on the photo).
The species was described, named and dedicated to our recently deceased colleague, a keen natural historian and Honorary Curator at the Manchester Museum, Mrs Claire Miles (1958–2023).
For the moment, this spider species is known only from the Tremough campus, Penryn, Cornwall, United Kingdom. However, the actual origin of this species is yet to be revealed. The genus Anasaitis is essentially Caribbean, whereas the country of origin of the British population and the date of its actual arrival to the UK remain unknown.
It is known that alien jumping spiders were among those spider groups that were first introduced (or, better said, first recorded as being introduced) to Europe, dating back to the first half of the 19th century: viz., Menemerus bivittatus in 1819 and Plexipus paykulli in 1831 (see here). Both species (currently pantropical) successfully established in south-western Europe, but not in the UK. To date, 18 accidentally imported jumping spiders have been reported from England, of the approximately 50 species of all alien spiders recorded. Only two of them – Hasarius adansoni (here and here) and the newly described Anasaitis milesae – have been able to successfully colonise Britain; the former is known only from greenhouses and other indoor environments.
Dr Dmitri Logunov, Honorary Research Fellow at the Manchester Museum
Entomology Manchester 