The families of British spiders

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L. Watson and M. J. Dallwitz

Thomisidae

Excluding Philodromidae.

Crab Spiders.

Morphology. The adult spiders 2–10 mm long; mostly decidedly plump-bodied, or of medium build (in some males); decidedly short-legged, or with legs of medium length, or decidedly long-legged (from about as long as the body to over three times as long); markedly crab-like in stance and locomotion; with eight eyes (black and beady, occasionally dark blue-grey). The eyes in two horizontal rows of 4 (the laterals often on tubercles); all dark. The palpal organs of the male of complex structure and enclosed by the specialized, hollowed tarsal segment (the cymbium). The front legs not short and stout. The first two pairs of legs forwardly directed, laterigrade; conspicuously longer and often stouter than the third and fourth pairs (resulting in the characteristic, crab-like stance and sideways locomotion). Metatarsus IV of the females without a calamistrum. Scopulae absent. Tarsal claws 2. The tarsi without claw tufts. The abdomen angular in shape (sometimes, e.g. in Thomisus onustus), or angular in shape; conspicuously patterned dorsally (usually, occasionally green), or plain dorsally; occasionally exhibiting red or pink colour, but neither predominantly bright red and black nor predominantly bright red and yellow (or at least pink, e.g. in female Thomisus onustus), or without any red coloration; with a single, inconspicuous tracheal spiracle. The anterior spinnerets close together. The abdomen of the females without a cribellum. The reproductive openings of the females associated with an epigyne.

The adults not making snare-webs; lying in wait for their prey (on the ground, in vegetation or in flowers, often cryptically coloured and some, e.g. Misumena vatia, actively changing colour to match the background; the prey being seized with the large and often spiny front legs).

British representation. 25 species in Britain; in the genera Diaea, Misumena, Ozyptila, Pistius, Thomisus, and Xysticus.

Comments. These species have legs I and II longer and stouter than III and IV, reflecting the characteristic, crab-like posture and locomotion.

Illustrations. • Diaea, Ozyptila, Thomisus and Xysticus. • Diaea, Misumena, Ozyptila, Thomisus.


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’.

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