Review On The Crab Spider Genus Xysticus C. L. Koch, 1835(Araneae: Thomisidae)

The crab spiders(Thomisidae) are hunting or waiting for preying on past insects on all kinds of plants without a web during the day usually, which are widely distributed almost all kinds of ground eco-systems on the earth. To date, there are 176 genera, 2157 species known from the world and 47 genera, over 280 species from China. Xysticus C. L. Koch, 1835 is the largest group, which includes 373 known species from the world and 66 species in China(World Spider Catalog 2015). At the beginning of the study, most of the crab species were blindly fell into the genus Xysticus which has leaded to the confusion of classification: there are many species were classified as Xysticus mistakenly; there are also a lot of species were transferred to other genera such as Ozyptila wrongly; and there are also some species were established just by a junior or a male or a female spider. Further more, the lack of details for pictures of some species’ genitals is common, and some even without the pictures available for reference. Moreover, because of lack of efficient communication among international and domestic academics has leaded to some cases such as some species were identified incorrectly or synonymed with other species or even mismatched. There are 6 juvenile and 158 single sex and nearly half of the species were quoted in only one publication and even 20 species didn’t have any pictures available for reference amang Xysticus species. The revision of all Xysticus species is almost impossible due to the unavailble specimens from nearly all continenents of the world. Based on the literatures, we list 18 known species and two new species of X. somaculatus sp. nov. and X. paralepnevae sp. nov. are newly found and 22 color photos. In addition, we also point out the mistaken identities and the synonyms and the mismatch situations which still need to be validated by checking the type specimen of the known species.