From Durham to Dalby

 

Durham Slug Arion flagellus, now a wide spread species in Yorkshire. 

Having taken a bit of a computer break I have a backlog of ecological observations and where better to start than with more slugs. This is the Durham Slug Arion flagellus which interestingly is another non-native species like my earlier post on Ambigolimax valentianus, also like this species 'Durham Slugs' originate in the Iberian peninsula and found their way to Britain during the 1970's. A species originally first recorded from the Wirral and Durham (hence the name), which has quickly spread across Britain. 

Numerous species of invasive non-native slugs are thriving in Britain, causing a threat through competition and hybridization. The Durham Slug is considered to be a risk to native Arion species like A. ater. This species reproduces rapidly (about twice the rate on native species) and quickly colonise suitable areas. Interestingly their impact on A. ater in some areas is causing a distributional shift in our native species, reducing it to moorland and upland woodland sites less favoured by A. flagellus. 

A trip upto Dalby Forest in December found this species to be very common, worryingly with a restricted number of A. ater. A.flagellus can be identified from similar species like A. subfuscus through its colourless mucus and larger tubercles on its back (6-9 rows between the two dark later stripes behind the mantle). The crests of these tubercles also tend to be yellow tipped. 

A. flagellus is a variable species showing a variety of colours like this bright orange specimen.