The families of British spiders

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L. Watson and M. J. Dallwitz

Pisauridae

Including Dolomedididae.

Nursery-web Spiders, Raft Spiders.

Moving across the surface of still water to take victims from it (Dolomedes), or terrestrial.

Morphology. The adult spiders 9–22 mm long; slender-bodied, or of medium build; decidedly short-legged, or with legs of medium length (less than twice the body length); with eight eyes. The eyes ostensibly in three rows of 4+2+2, the anterior row of four more or less recurved (comprising a recurved front row of four small, equal-sized members, and two pairs of larger, equal-zized eyes forming a trapezium behind). The palpal organs of the male of complex structure and enclosed by the specialized, hollowed tarsal segment (the cymbium). The trochanters of all the legs notched. Metatarsus IV of the females without a calamistrum. Tarsal claws 3. Tarsus IV without a ventral ‘comb’. The abdomen conspicuously patterned dorsally. The abdomen of the females without a cribellum. The reproductive openings of the females associated with an epigyne.

The adults not making snare-webs (but the females construct nursery webs for the protection of their young); actively pursuing their prey (ground running, and in the case of Dolomedes moving over still water to take prey, the movements of which are detected by a submerged leg as the spider lies in wait at the water’s edge. Dolomedes sometimes takes small fish, as well as invertebrates). The females carrying egg sacs via their chelicerae and palps.

British representation. 3 species in Britain; in the genera Dolomedes and Pisaura.

Illustrations. • Dolomedes fimbriatus and Pisaura mirabilis.


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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