The families of British spiders


L. Watson and M. J. Dallwitz



Running Crab Spiders.

Morphology. The adult spiders 4–7 mm long; of medium build to decidedly plump-bodied (mostly), or slender-bodied (e.g., conspicuously so in male Tibellus); decidedly short-legged, or with legs of medium length; not crab-like in stance and locomotion (at least, less obviously so than in the related Thomisidae); with eight eyes (black and beady). The eyes in two horizontal rows of 4; all dark; not ringed with white hairs. The palpal organs of the male of complex structure and enclosed by the specialized, hollowed tarsal segment (the cymbium). The first two pairs of legs forwardly directed, laterigrade; conspicuously longer and often stouter than the third and fourth pairs (but the stance and locomotion less obviously crab-like than in Thomisidae), or not markedly longer and stouter than the third and fourth pairs. Metatarsus IV of the females without a calamistrum. Tarsal claws 2. The tarsi with claw tufts. The abdomen conspicuously patterned dorsally. The abdomen of the females without a cribellum.

The adults not making snare-webs; actively pursuing their prey (active on foliage and ground vegetation, sometimes in buildings, and capable of rapid movement).

British representation. 15 species in Britain; in the genera Philodromus, Thanatus, and Tibellus.

Comments. The form, posture and locomotion of these active hunters are less obviously crab-like than in the sedentary Thomisidae s. str., of which this family is a recent segregate.

Illustrations. • Philodromus dispar, Philodromus histrio. • Philodromus cespitum. • Philodromus margaritatus, Tibellus sp..

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.’.