Snail anchor
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Snail anchor ( Ischyropsalis hellwigii ) |
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| Scientific name | ||||||||||||
| Ischyropsalis hellwigii | ||||||||||||
| ( Panzer , 1794) |
The snail anchor ( Ischyropsalis hellwigii , Syn .: Ischyropsalis hellwigi ) is the eponymous species of the snail anchor family belonging to the harvestmen . It feeds on shell snails, whose shells it breaks open with its powerful chelicerae . The species has a large distribution area in southern, western and central Europe, but is usually rare.
features
The body length of the females is 6.8–8.5 mm, that of the males 5.5–7.0 mm. The body is brown to black in color, one-piece and oval shaped. The abdomen is relatively strong, plump and marked with transverse grooves. Older animals are completely black. The two small, point-shaped eyes sit on top and lie on the sides of an ocularium, which is typical for harvestmen. The strongly developed chelicerae can be over 10 mm long and are spread out always longer than the body. The base member of the Chelicerae is thorny, the third member of the Chelicerae, the Chela , has the shape of a forceps. Despite their small size, these tongs are very powerful at breaking up snail shells. The Pedipalps are heavily covered with sensory hair. The legs are relatively short for harvestmen, but relatively long for snail anchors and longer than the body. They are usually darker in color than the body, with the tarsi and metatarsi being slightly lighter. The tarsi are subdivided into many small dummy segments, which means that the species can hold onto plants well. Freshly skinned animals have yellow legs with black central links.
Similar species
A number of similar species can be found in Central Europe, for example the shorter Kleine Scherenkanker ( Ischyropsalis carli ). In Germany it can only be found in the Allgäu and also in the Alpine region. Ischyropsalis dentipalpis , which also lives in Switzerland and Austria, is also widespread in the southern Alpine region . The species Ischyropsalis hadzii and Ischyropsalis kollari also occur in the southeastern Alpine region and thus also in Austria . In southern Europe, the species diversity is greater than in Central Europe and there are numerous other species that often inhabit caves.
Distribution, habitat and endangerment
The nominate form of the snail anchor is widespread in Central Europe and known from the following countries: Germany , Austria , Poland , the Czech Republic , Slovenia , Hungary , Croatia , Bosnia and Herzegovina and Northern Italy . In the 19th century the species was also found in Denmark . In Germany they are found more frequently in the central, southern and southeastern areas than in the northwest and almost only east of the Rhine . Especially in Baden-Württemberg , Hesse or in the border areas to the Czech Republic, the species is detected more frequently. The subspecies Ischyropsalis hellwigii lucantei occurs to the west of it, from the Cantabrian Mountains in northern Spain over the western Pyrenees to France . It therefore lives in a disjoint sub-area that is delimited and far away from the distribution area of the nominate form.
The species inhabits semi-natural deciduous forests, mixed forests, heaths and, more rarely, coniferous forests in damp, cool valleys in the central and foothills as well as the Alps and can be found here on tree stumps, on damp foliage or under moss, deadwood or stones. Areas rich in snails are preferred. The species is dependent on cool weather and high humidity and cannot survive long without this microclimate. It is quite possible that the species and the entire genus are relic species that were more widespread in the cold ages. During the day the animals rest hidden. Since numerous hiding places are necessary for the species, it only lives in near-natural forests and can be described as a "cultural refugee". The species is not common, even in sparse occurrences, and generally difficult to find. In Germany it is on the warning list of the Red List of Threatened Species, in Austria it is considered endangered.
Way of life
The crepuscular and nocturnal snail snails, like the board snails, have specialized in slugs and shell snails , for example the genus Cernuella . The mouth rim of the housing is held with a pair of chelicerae pliers, while the housing is broken open piece by piece with the other pair of pliers. Pieces are then gradually torn out of the exposed soft body of the snail and eaten. Adult specimens are mostly found between July and October. During courtship, the male releases secretions with pheromones from the glands of the chelicerae, which the females perceive. The pairing can take a few seconds to a few minutes and can be repeated several times. The partners stand head to head opposite one another. With the tarsi of the two front pairs of legs, the male teases the female, who with its mouth touches the glandular field on top of the basal limb of the male's chelicerae. The male now pushes his long mating member, which appears in a crevice under the ventral shield, into the genital opening at the same place on the female. In late summer, the females lay their eggs with a long, flexible laying tube in gelatinous balls, mostly under pieces of wood or in the ground. The offspring sometimes hatch in autumn, but usually not until the following spring. Ischyropsalis hellwigi lives for less than a year.
Taxonomy
The basionym of the species is Phalangium hellwigi , another synonym of the species Ischyropsalis taunica Müller . The species was named after Johann Christian Ludwig Hellwig . The species is divided into the subspecies Ischyropsalis hellwigii hellwigii and Ischyropsalis hellwigii lucantei Simon 1879.
literature
- Michael Chinery: Parey's Book of Insects . Franckh-Kosmos Verlags-GmbH & Co., Stuttgart 2004, ISBN 3-440-09969-5 , p. 301.
- Dr. Helgard Reichholf-Riehm, Ruth Kühbandner: Insects with appendix arachnids (Steinbach's natural guide) New, edited special edition. Mosaik Verlag, Munich 1984, ISBN 978-3-576-10562-1 , p. 266.
Web links
- Ischyropsalis hellwigi hellwigi . In:Wiki of the Arachnological Society. .
- Schneckenkanker at: www.spinnen-nationalpark-schwarzwald.de, The Spider Fauna of the Black Forest National Park , a project of the Natural History Museum Karlsruhe, accessed on January 7, 2021. Contains macroscopic photographs of the species.
Individual evidence
- ↑ Martens J (1965) distribution and biology of Schneckenkankers Ischyropsalis hellwigi [Distribution and Biology of the snail-cracking harvestman Ischyropsalis hellwigi (Arachnida: Opiliones)]. Nature and Museum 95 (4): 143–149. link
- ^ Ischyropsalis hellwigi (Panzer, 1794) in GBIF Secretariat (2019). GBIF backbone taxonomy. Checklist dataset [1] accessed via GBIF.org on January 7, 2021.