Thomisus onustus
Encyclopedia
Thomisus onustus is a crab spider
species in the genus Thomisus
belonging to the family Thomisidae.
distribution from Great Britain and Portugal in the West to Japan in the East. It is present in most countries of Europe
, but it is absent in Iceland, Ireland, Norway, Denmark and Finland. North-south distribution extends from Sweden to South Africa and from Siberia to Central Java, including temperate and tropical ecozone.
In males the basic colour of the prosoma varies from yellow brown to dark brown, the opisthosoma
may be yellow and green or brown. Also females are very variable in colour, their basic colour can be white, yellow or pink.
As a matter of fact these crab-spiders hide themselves adapting the colour of their body to the colour of the flowers on which they are waiting for preys, a behaviour that conceal them from predators and from the pollinating preys.
Crab spider
Crab spider is a common name applied loosely to many species of spiders, but most nearly consistently to members of the family Thomisidae...
species in the genus Thomisus
Thomisus
Thomisus is a genus of crab spiders with more than 100 species described. The genus includes species that vary widely in their ecology, but the best known crab spiders are those species that people call the flower crab spiders, because they are ambush predators that feed on insects visiting flowers...
belonging to the family Thomisidae.
Distribution
It has a PalearcticPalearctic
The Palearctic or Palaearctic is one of the eight ecozones dividing the Earth's surface.Physically, the Palearctic is the largest ecozone...
distribution from Great Britain and Portugal in the West to Japan in the East. It is present in most countries of Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, but it is absent in Iceland, Ireland, Norway, Denmark and Finland. North-south distribution extends from Sweden to South Africa and from Siberia to Central Java, including temperate and tropical ecozone.
Description
This species shows an extreme sexual dimorphism both in size and coloration, also in comparison with othe crab spiders. The adult males reach a body length of only 2–4 mm (0.078740157480315–0.15748031496063 ), while females are 7–10 mm (0.275590551181102–0.393700787401575 ) long. This species is characterized by the prominent rear corners of the opisthosoma.In males the basic colour of the prosoma varies from yellow brown to dark brown, the opisthosoma
Opisthosoma
The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma . It is a distinctive feature of the subphylum Chelicerata...
may be yellow and green or brown. Also females are very variable in colour, their basic colour can be white, yellow or pink.
As a matter of fact these crab-spiders hide themselves adapting the colour of their body to the colour of the flowers on which they are waiting for preys, a behaviour that conceal them from predators and from the pollinating preys.