The families of British spiders
Purse Web Spiders.
Morphology. The adult spiders 7–18 mm long; slender-bodied to of medium build (males), or of medium build to decidedly plump-bodied (females); decidedly short-legged (somewhat shorter than the body to only slightly longer); with eight eyes. The eyes comprising two relatively large medians, with three small laterals in triangular arrangements on either side. The chelicerae articulated to move upwards and downwards, lying parallel to the long axis of the body, and relatively massive. The palpal organs of the male of complex structure and enclosed by the specialized, hollowed tarsal segment (the cymbium). Metatarsus IV of the females without a calamistrum. Tarsal claws 3. The abdomen plain dorsally. The posterior spinnerets 3-segmented (and long). The abdomen of the females without a cribellum.
The adults constructing a terrestrial retreat in the form of a silk tube (most of this being buried in soft earth or litter); not making snare-webs; lying in wait for their prey (the spider lurks within the exposed part of its tube, and it spears insects crossing this, pinning them against the wall with its long fangs; then it cuts the wall with its specially-adapted chelicerae, in order to drag the victim inside for consumption).
British representation. 1 species in Britain; in the genus Atypus (A. affinis).
Illustrations. • Atypus affinis.
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. The families of British spiders. Version: 4th January 2012. http://delta-intkey.com’.