Brown crab spider
| Brown crab spider | ||||||||||||
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Brown crab spider ( Xysticus cristatus ), female with a captured scorpion fly |
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| Scientific name | ||||||||||||
| Xysticus cristatus | ||||||||||||
| ( Clerck , 1757) |
The brown crab spider or bush crab spider ( Xysticus cristatus , syn .: Xysticus viaticus ) is a spider from the family of crab spiders (Thomisidae).
features
The females are 6 to 8 millimeters, the males 3.5 to 5.6 millimeters long. The basic colors are dark and light brown tones. The front body ( prosoma ) has broad, dark stripes laterally. It is characterized by a large triangle on the upper side of the prosoma with a black point on its rearward tip. This triangle is bordered on two sides by light stripes that unite at the top to form a wide band. On the back of the body ( opisthosoma ) there is a large drawing of leaves, which is usually lighter than the rest of the color. A light brown to ocher-colored band runs in the middle, from which three transverse lines or spikes extend, which divide the area up to the edge. The colors and markings are variable, the males are generally generally darker than the females.
The legs have dark spots, spots and stripes. Four eyes look forward, with the two larger eyes arranged on the outside. Behind these eyes is another row of four eyes that are directed upwards. There is a sharp, light dividing line between the two rows.
female
The prosoma is slightly smaller in females than the opisthosoma, but the connection between the two is wide, so that when viewed from above, a violin-shaped outline can be seen. Prosoma and opisthosoma are ovally rounded, flattened at the top and drop off steeply to the sides. The sides are white with olive-brown arched lines. The legs are yellowish-white, the thighs, knees and splints of the two front pairs of legs are rust-brown, rather densely dotted, on the two rear pairs of legs they are dotted with less brown dots.
male
The smaller males resemble the females in the construction of the prosoma, but the opisthosoma is narrower and only slightly longer than the prosoma. The opisthosoma is flattened at the top and slopes down almost angularly to the sides. The drawing on the back is also narrowed and usually has a yellowish tint that shows brown tones towards the middle. The sides are pure white and covered by dark brown wavy stripes that fork and probably represent a camouflage pattern similar to that of a zebra. The parts of the prosoma that are brown in the female have a darker, brown-black color in the male. The hips, thighs and knees of the two front pairs of legs are also brown-black or even completely black, on the two rear pairs of legs they are brown. The other limbs of the legs are brownish yellow, only the upper end of the rails is also brown.
In Central Europe there are a number of very similar species of the genus; the reliable determination of the species is only possible through the macroscopic examination of the genital organs (genital morphological).
Occurrence
The species is widespread in the Palearctic and occurs throughout Europe . In the south, for example in southern Spain and southern Italy as well as North Africa and in the east to Central Asia and Siberia, the frequency is continuously decreasing. In contrast, the species is common everywhere in Northern Europe.
It is widespread in meadows and on the edges of forests with half-height vegetation and lives in heathland and vineyards. However, it can also be found in many other habitats with the exception of dry deciduous forests and ruderal zones .
Mature specimens of the brown crab spider can be seen from April to June.
Way of life
nutrition
The brown crab spider lurks in the herb layer and on bushes for its prey. This consists of small insects, but also larger ones like hornets and larger butterflies . Above all, many beetles fall victim to the spiders. If the prey is close enough, they rush towards it at lightning speed and overwhelm it. With the front, longer pair of legs, the prey is held and also kept away so that even defensive hymenoptera cannot sting.
Reproduction
Before mating, the male wraps threads around the female. This is only part of the partner acquisition , because after the mating the female can free herself from the threads. From an evolutionary point of view, this "bondage" could be important for the survival of the male after mating, because it gives him some time to withdraw.
Like the mutable crab spider , the egg cocoon is guarded. Here the spider mother sits on the egg cocoon, she no longer hunts and guards the egg cocoon until she dies. The young spiders hatch towards the end of summer and overwinter in cracks in the ground.
Danger
The species is widespread and common in suitable habitats . It is classified as "harmless" in the Red List , and the brown crab spider is the most common species of its genus.
Taxonomy and systematics
The spider was already described in 1757 by the Swedish arachnologist Carl Alexander Clerck as Araneus cristatus in his fundamental work Svenska Spindlar . The genus Xysticus was established by Carl Ludwig Koch in 1835 . In Koch's time, Xysticus cristatus was known under the name Xysticus viaticus , after Carl von Linné , who named this spider Aranea viatica in his work Systema Naturae from 1758 . It was not until late in the 20th century that Clerck's work, published a year before Linnaeus' Systema naturae , was recognized. Since the beginning of the binary nomenclature is fixed at 1758, Clerck's work and its priority is the only exception: the arachnids described by him would have to be the year 1758 for the first description according to a specification in the 4th edition of the ICZN code from 1999 However, this led to a lot of misunderstanding and therefore most zoologists use the year 1757, the year of the appearance of Svenska Spindlar .
Xysticus cristatus is named for a group of closely related European species. This group includes Xysticus pseudocristatus Azarkina & Logunov , 2001 , Xysticus audax ( Cabinet , 1803) , Xysticus macedonicus Silhavy , 1944 and Xysticus brevidentatus Wunderlich , 1995 .
literature
- Heiko Bellmann: Cosmos Atlas Arachnids of Europe. And freshwater crabs, woodlice, millipedes. Franckh-Kosmos, 2006, ISBN 3440107469
- Dick Jones: The Cosmos Spider Guide. Franckh-Kosmos, 1990, ISBN 3440061418
Individual evidence
- ↑ According to the definition of the ICZN in the 4th edition of the ICZN code 1999, the earliest possible year for the first description of an animal according to the binary nomenclature should be 1758, but most scientists consider it the year 1757, when Clerck's description in Svenska spindlar published (see also Norman I. Platnick: Familie Thomisidae in The World Spider Catalog, Version 11.0, 2010).
- ↑ Identification key ( Memento of the original from May 14, 2017 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. for the European species of the genus Xysticus in "Spinnen Mitteleuropas" on the website of the University of Bern
- ^ A b Carl Ludwig Koch and Carl Wilhelm Hahn : The arachnids. Depicted and described true to nature. Volume 12, 1845, pp. 71-74
- ↑ Spider assemblages and habitat bindings ( Memento of the original from October 7, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Habitat types for Xysticus cristatus in "Spinnen Mitteleuropas" on the website of the University of Bern
- ↑ Carl Alexander Clerck : Svenska spindlar , uti sina hufvud-slågter indelte including under några and sextio särskildte arter deskrefne and with illuminerade figurer uplyste. Stockholm 1757, p. 136 (first description)
- ↑ Carl Ludwig Koch: Arachnids. In: GAW Herrich-Schäffer: Deutschlands Insekten , Heft 128-133, 1835
- ^ Elke Jantscher: Xysticus brevidentatus (Thomisidae): Further Records and First Description of the Female. Journal of Arachnology, 31, pp. 363-370, 2003
Web links
- Xysticus cristatus in Fauna Europaea
- Xysticus cristatus at Eurospiders.com, with photos of epigyne , palps andspinneret glands