Motherphage Spider

Similar in appearance to some of the Amaurobius species, the Motherphage Spider (Coelotes atropos) is actually part of the Agelenidae family which includes the big 'house spiders' of the genus Tegenaria. The motherphage spider is almost identical to Coelotes terrestris. This specimen was recorded from Exmoor near Dunkery Beacon in the UK.



The motherphage spider is widespread throughout the UK except south-east England and Scotland. Outside of the UK it can be found across Europe and Scandinavia. This specimen was found under a large stone on moorland, but it also favours stones, bark and logs on heathland, woodland and mountains.


Mother and egg sac


The rounded abdomen is dark brown with pale spots/chevrons in a v-shape running from base to spinners. The carapace is a red-brown colour, becoming darker towards the large chelicerae (mouthparts). The long legs are a mix of dark and light red-brown. The abdomen can be a lot lighter than the specimen shown, with very clear visible patterns. The male is similar to the female, but with a smaller more slender abdomen and long extended pedipalps. The young spiderlings have large rounded pale yellow abdomens, with pinkish carapace and legs. The female reaches a length of 9 - 13mm and the male reaches 7 - 10mm.



The motherphage spider eats small insects and invertebrates. It builds a silk lined burrow with a funnel retreat, at the end of which it lays its eggs. The young spiderlings will feed on the mothers prey (via regurgitation), but as winter approaches the adult mother dies and the spiderlings will consume her. A very protective mother, the motherphage spider will protect her egg sac during the incubation period (known as egg sac guarding).


Motherphage spiderlings


Although no microscopic examination was taken, we have classified it as C. atropos due to its appearance and its location. C. terrestris is more common in south-central and south-east England. Most of the specimens of C. atropus we have seen have very clear and distinct markings, this specimen is a little darker than most and appears closer to C. terrestris, but colour and pattern is never a good guide.