| | The spider families of Britain and Ireland |
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).
Representation in Britain and Ireland. 1 species in Britain; in the genus Atypus (A. affinis).
Illustrations. • Atypus affinis. Atypus affinis Eichwald. a, female; b, male; c, female in profile view; d, female, from below; e, eyes; f, portion of leg; g, extremity of palpus of the female; h, palpus with palpal organs of the male. From Blackwall (1861, with approximate length of the female added).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. The spider families of Britain and Ireland. Version: 5th August 2019. delta-intkey.com’.
