New spiders found in Northern Ireland

Friday 5th January 2018

Three new spiders have been discovered in Northern Ireland during surveys undertaken by wildlife charity Buglife which were funded by the Northern Ireland Environment Agency. 
The Arcane tongue spider (Centromerus arcanus), Tree Comb-foot Spider (Anelosimus vittatus) and  Tree H-weaver (Episinus maculipes) have not previously been recorded in Northern Ireland, and will now be added to the list of 292 spider species known from the country.
Adam Mantell, Buglife Northern Ireland Manager said “These are some exciting finds, and show how there is so much more to discover about Northern Ireland’s wildlife.  Our protected sites are vitally important for the conservation of invertebrates, our surveys are helping to manage them in the right way to conserve their wildlife riches”
A tiny money spider, the Arcane tongue spider (Centromerus arcanus) was found at Breen Wood near Ballycastle.  In most of Europe it is found only amongst forest litter in mountainous areas, though in Britain and Ireland it appears to be a species of mountain summits and bogs as well.
At Rostrevor Wood in County Down, the Tree comb-foot spider (Anelosimus vittatus) was found for the first time on shrubs in forest rides.  
Also from Rostrevor Wood was a rare spider called the Tree H-weaver (Episinus maculipes).  This species was first recorded in Britain in 1929 and has gradually been expanding its range.  This record appears to be the most northern in Europe suggesting it is doing the same on this side of the Irish channel. Episinus spiders have a unique way of catching prey.  At night they spin an H-shaped web in low vegetation in which they hang upside down to catch prey passing beneath.
Our warming climate may be playing a significant role in the fates of these species. Many invertebrates have very precise requirements for temperature and humidity. The Arcane tongue spider for example is a species of cold, damp habitats and may be lost in Ireland if temperatures continue to rise.  The Tree H-weaver spider on the other hand is mainly found in southern Europe and is likely to become much more common.
These finds also show the importance of monitoring invertebrate populations so that we understand more about how our smallest animals are changing in the wild.  Good habitats are becoming increasingly fragmented in the modern landscape which isolates populations and makes them vulnerable to change and extinction. Buglife is working with NIEA and others to ensure that our invertebrates have a brighter future.