ARACHNIDA > ARANEAE > Thomisidae > Misumena and Thomisus

Previously lumped together with the Philodromidae 'running crab spiders', this family includes 27 species in 7 genera; Diaea (1), Misumena (1), Pistius (1), Synema (1), Thomisus (1), Ozyptila/Cozyptila (10) and Xysticus/Bassaniodes (12).

The genera represented by a single species are distinctive, but Ozyptila and Xysticus, and their closely related genera, contain a number of species that are fairly similar in general appearance and, consequently, difficult to identify. They are dealt with separately on the next page. That leaves five species, two of which are extremely rare.

They are squatter and dumpier than the Philodromidae species, with shorter legs that gives them even more of a crab-like appearance. They have eight, black and beady, eyes in two rows of four, the laterals of which are often on tubercles. Their first two pairs of legs are turned forwards.

Crab spiders don't construct webs to catch their prey, but instead prefer to lay in wait either on the ground or more likely on vegetation where some species will wait in the cups of flowers that provide camouflage. Prey is restrained with the first two pairs of legs, which are often armed with spines.

The Flower Crab Spider, Misumena vatia, is a relatively common southern species. The female is considerably larger than the male and unmistakable with her large, white to bright yellow coloured abdomen, which sometimes has a pair of red side stripes or patches, and a similarly coloured carapace with variable pale green lateral bands. The legs are the same colour as the rest of the body. The small male, with a body length of only 3-4mm, is seldom photographed as he tends to stay lower down in the vegetation. Whereas the female is a consistent white colour throughout, the male has a brown carapace and distinctive front legs (both pairs) that are brown in part and then annulated. I've seen a few females but, to date, no males.

The Heather Crab Spider, Thomisus onustus, is a nationally scarce species restricted to just a few areas in the south, primarily on heathland where it typically occurs on heather, but occasionally can be found in gardens on plants. The choice of plant has little consequence as it has the ability to change colour to give it better camouflage. It's a very attractive sought-after species that many people spend ages looking for. I was lucky as my daughter found one in her garden, and it was a beautiful pink female. They have a  carapace with a broad whitish central band, and a variably coloured abdomen that, when viewed from above, has a truncated triangular shape. The colour of the legs is also variable, matching but normally darker than the abdomen. I believe that a paler pink version of the individual featured here is the more typical form, but there is also a pink-and-white and yellow form. The males are smaller and predominantly brown in colour.

The final species is the Green Crab Spider, Diaea dorsata, which I've yet to see. It mainly occurs in woodland where there are Box, Yew or other conifers.

Continues on the next page ....

Updated, Jan.25 (v.3)