Xysticus is a genus of ground crab spiders described by C. L. Koch in 1835, belonging to the order Araneae, family Thomisidae. The genus name is derived from the Ancient Greek root xyst, meaning "scraped, scraper".
Xysticus and Coriarachne are dark brown or reddish-brown crab spiders often encountered on weeds or trees. While similar to the 'flower spiders', they tend to have shorter, sturdier legs. Many, but not all, species have abdomens more patterned than most Thomisus species, rather like some of the Synema species. Some however, that are more terrestrial, resemble earth in colour and texture.
A ground crab spider with earthy coloration
Most species of the genus Xysticus are small to medium sized spiders. They show a sexual dimorphism in size. Females of typical species reach a maximum of 10 millimetres (0.39in) of body length, while their males are about 3–5 millimetres (0.12–0.20in) long, about half the size of the females.
The basic colour of these species is usually brown, beige or gray. The prosoma is sometimes slightly smaller than the opisthosoma. In many species the front body shows in the middle a broad, pale longitudinal band. The opisthosoma is clearly flattened in most species and shows a median broad and dark leaf marking.
The species are often very similar to each other, and in most cases can be distinguished only by a microscopic examination of the reproductive organs.
Behaviour
The spiders of the genus Xysticus do not build webs; like most Thomisidae they are ambush hunters and prefer to hunt near the ground (hence the common name "ground crab spiders"). They move slowly, and commonly hunt by stationing themselves in a high-traffic area and grabbing whatever arthropod passes close enough. Also like most other Thomisidae, they seize prey with their enlarged anterior two pairs of legs and kill it by a venomous bite.
Species
As of December2022[update] it contains 293 species, found worldwide:[1]
Thanatus is a genus of false crab spiders described by Carl Ludwig Koch in 1837, belonging to the order Araneae, family Philodromidae.
Drassodes is a genus of ground spiders that was first described by Niklas Westring in 1851. They are brown, gray, and red spiders that live under rocks or bark in mostly dry habitats, and are generally 3.8 to 11.6 millimetres long, but can reach up to 20 millimetres (0.79 in) in length.
Ozyptila is a genus of crab spiders that was first described by Eugène Louis Simon in 1864. It has been misspelled as "Oxyptila" in multiple accounts.
Clubiona is a genus of sac spiders that was first described by Pierre André Latreille in 1804.
Tmarus is a genus of crab spiders, comprising 227 species:
Pardosa is a large genus of wolf spiders, commonly known as the thin-legged wolf spiders. It was first described by C. L. Koch, in 1847, with more than 500 described species that are found in all regions of the world.
Zelotes is a genus of ground spiders that was first described by J. Gistel in 1848.
Gnaphosa is a genus of ground spiders that was first described by Pierre André Latreille in 1804. They all have a serrated keel on the retromargin of each chelicera.
Synema is a genus of spider in the family Thomisidae, found in most parts of the world.
J. H. Redner and C. D. Dondale (1965). A New Species of The Spider Genus Xysticus (Araneae: Thomisidae) From Arizona - Psyche 72(4): 291–294.
H. Demir, O. Seyyar, and M. Aktaş (2008). A Poorly Known Species of the Spider Genus Xysticus C. L. Koch (Araneae, Thomisidae) in Turkey. Archives of Biological Sciences 60(4): 17P-18P.
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