Thomisus onustus is a crab spider species in the genus Thomisus belonging to the family Thomisidae.

Description

This species shows sexual dimorphism both in size and coloration. The adult males reach a body length of only {{convert|2|-|4|mm}}, while females are {{convert|6|-|7|mm}} long. In males, the basic colour of the prosoma varies from yellow brown to dark brown, the opisthosoma may be yellow and green or brown. Females are very variable in colour, their basic colour can be white, yellow pale brown or pink, sometimes with additional shades of red. This species is characterized by the prominent rear corners of the opisthosoma.

Prey

Like other species of the family Thomisidae these crab spiders do not make a web, but wait in ambush for their prey on flowers. The spiders are disguised by assuming the same colour as the flower, fooling both insect and bird predators. The prey consists of flower-visiting insects of all species, such as hover flies, bees, wasps, butterflies or beetles, which are often several times larger than the spider. They take their prey with two powerful and highly enlarged front leg pairs and usually kill them by biting on the back of their neck. Emerging spiderlings of Thomisus onustus may feed on pollen or nectar when insect prey is lacking.

Reproduction

Mating takes place mainly in June. The male climbs onto the back of the female to copulate. Finally, the male leaves the female. The female during the entire mating is completely passive and does not show any aggressive behaviour.

Distribution and habitat

It has a Palearctic distribution, being found from Great Britain and Portugal in the west to Japan in the east. It is present in most countries of Europe, but is absent in Iceland, Ireland, Norway, Denmark and Finland, and it has also been seen in Iraq.{{citation needed|date=April 2018}} Its north–south distribution extends from Sweden to South Africa and from Siberia to Central Java, including temperate and tropical ecozones.{{citation needed|date=April 2018}} These spiders prefer warm temperatures, forest-free areas, dry and sandy habitats with high solar radiation and dry grasslands.{{citation needed|date=April 2018}}

Gallery

See also

• List of Thomisidae species

References