Polydesmus asthenestatus Pocock, 1894
GB IUCN status: Not applicable (non-native)
This small flat-back millipede (c. 8.5-10 mm in body length) can be easily confused with Brachydesmus superus or other Polydesmus species (notably the recently discovered P. taranus, a slightly larger species) and identification is best undertaken by examination of male gonopods.
Distribution and Habitat
First discovered in Co. Down, Northern Ireland, in 2008 by Roy Anderson (2015) and subsequently in Co. Antrim. Here it has proved to be widely established mainly in 'disturbed woodland'.
In Britain P. asthenestatus was first recorded in a cave in Cornwall in 2020 (Knight, 2021) and an ornamental garden in Cornwall in 2021 (Gregory, 2023). Subsequently (in 2023) it has been recorded from the Isle of Wight, the Isle of Man and south Wales. It is likely to be found at additional sites.
Adults can be found in the winter months.
At the Cornish and Isle of Wight sites it was found associated with the recently discovered Polydesmus taranus.
Anderson, R. (2015) The establishment of an Italian flat-back millipede Polydesmus asthenestatus Pocock, 1894 (Diplopoda: Polydesmidae) in Ireland. Bulletin of the British Myriapod & Isopod Group 28: 38-43.