About Amaurobius similis (Blackwall, 1861)
Description: Mature male Amaurobius similis have a body length of 6–8 mm, while mature females measure 9–12 mm. Their carapace is dark reddish-brown, with a darker colored head region. The upper surface of the abdomen bears a dark wedge-shaped marking, which is bordered by yellow on the side toward the anterior. The legs match the carapace in color, and have darker ring-shaped markings. This species is very similar in appearance to Amaurobius fenestralis; although mature A. similis are typically larger and darker in color than A. fenestralis, reliable identification between the two species requires microscopic examination of their genitalia. Distribution and habitat: Amaurobius similis has a Holarctic distribution, occurring throughout Europe and the Caucasus. It has also been introduced to North America. The species lives primarily in and around buildings, where it spins webs in gaps in walls, fences, and window frames. It is found less often under bark in more natural habitats such as woodland.
