Cylindroiulus pyrenaicus is a distinctive species since it bears both a projecting telson and ventral scale.
In Britain and Ireland, this combination of characters is otherwise only seen in C. apenninorum and Enataiulus armatus. The former is much larger, reaching 30mm or more in length, and the latter has conspicuous fringing setae on the metazonites.
The male gonopods are characteristic.
Distribution and Habitat
Although first discovered in Glamorganshire, south Wales, in 2004, it was not identified until re-found at nearby site in 2017.