Quadrangle
| Quadrangle | ||||||||||||
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Vierfleck ( Libellula quadrimaculata ) |
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| Scientific name | ||||||||||||
| Libellula quadrimaculata | ||||||||||||
| Linnaeus , 1758 |
The quadruped ( Libellula quadrimaculata ) is one of the large dragonflies and reaches a body length of 4 to 4.5 centimeters with wingspan between 7 and 8.5 centimeters. Each of the four wings has a noticeable dark spot in the area of the distinctive cross vein (nodus), after which the species received both its scientific and its common name. This dragonfly is also known for its mass migrations in swarms of impressive proportions. The entire stock is not considered to be threatened.
features
Construction of the Imago
   
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Capture mask from below (right button artificially opened) and from the front-below; bottom right button inside in plan view |
The adult quadrangle ( Imago ; pl. Imagines) reaches body lengths between 41 and 45 millimeters, of which 25 to 30 millimeters are on the abdomen . There is no pronounced sexual dimorphism ; So females and males look almost the same.
The animal has a yellowish face, which is delimited above by a black line between the antennae , and a dull brown thorax that is overgrown with hairs. The first six segments of the abdomen are brownish and, especially in younger specimens, slightly shimmering through, so that an airbag system used for thermoregulation is visible. Segments seven to ten are black and each have a yellow line on the side. The legs are colored black.
The rear wings reach a length of 31 to 38 millimeters, which results in a wingspan of seven or eight centimeters. The wing pattern, which is responsible for the name, consists of an amber-colored stripe on the wing base and a small black spot on the node . A distinction is made between 16 antenodal and 14 postnodal veins. There is also a small, triangular, black spot at the base of the hind wings. The veins of the hind wings are reddish-brown, the wing mark ( pterostigma ) brownish black and about four millimeters in length. The upper abdominal appendages of the males ( cerci ) are about three times as long as the lower ones and are very pronounced.
Construction of the larva
The larvae of the quadrangle are 22 to 26 millimeters long and around eight millimeters wide. They are orange-brown in color and their surface is covered with many small hairs. The abdomen (abdomen) is rounded and shorter than the legs, which gives the larvae a very squat appearance. The abdomen merges into five short, thorn-like appendages at the rear end, the so-called anal pyramid . Under these appendages, the cerci are only about 0.7 times as long as the paired side plates (ventrolateral plates) of the eleventh abdominal segment , the so-called paraproct . On the third or fourth to seventh segment there are weakly pronounced back spines, while these are missing on segments eight and nine. Instead, there are lateral mandrels here, which are downright tiny on segment eight. The skin protuberances in which the wings grow ( wing sheaths ) are around seven millimeters long.
The head is approximately six millimeters wide and has a convex shape at the top . The point eyes ( ocelles ) are already indicated as light points, the eyes, however, are stretched perpendicular to the central axis and sit on the lateral front edges of the head. The larva has eight to 13 small bristles on both sides of the unpaired front part of the lower lip , the so-called prementum . There are also seven to eight bristles on the triangular labial button. The gripping edge of the button is wavy.
The sensors consist of seven segments. While the first two are rather short and puffy, the remaining five are rather slim. The last, fifth and fourth segments are dotted. On the less muscular legs, the larvae have gray rings that darken with age and almost disappear after a while.
The legs and especially the lower legs ( tibiae ) are very hairy like the rest of the animal. The length of the legs increases from the front with twelve millimeters over the middle pair of legs with twelve millimeters to the rear up to 19 millimeters.
Similar species
As an imago, the species is relatively easy to distinguish from other species due to its distinctive wing markings. Most likely it can with the two spot ( Epitheca bimaculata ) or female of the top spot ( Libellula fulva be confused). In addition to the differently pronounced wing pattern in both species, a distinctive feature of the two- spot is the bulge of the posterior edge of the eye that occurs in the falcon dragonflies . In addition, the species is significantly larger and the two-spotted males patrolling the middle of the water are not to be confused with those of the four-spot just because of their different behavior.
The differentiation of similar species in larvae becomes more problematic. Here, for example, the larva of the flat belly ( Libellula depressa ) differs from that of the quadrangle in the following points: It has no lateral spines and on the labial palpus usually ten to twelve instead of the usually seven or eight bristles of the quadrangle, which makes it very difficult for laypeople to differentiate - this number of bristles can also vary in exceptional cases.
Habitats and distribution
The four-spot is a common type of dragonfly; its distribution area is in the Holarctic . It occurs accordingly in Central , Northern Europe and Asia as well as in Canada and Alaska . In the north, the species crosses the Arctic Circle and can be found in the Sørfjord in Troms at latitude 69 ° 30 'north.
The Vierfleck is characteristic of ponds rich in plants . It often occurs in high density ( abundance ) on the edge of silting waters, in swamps and on bog waters. The species is always to be found in acidic intermediate bogs , such as muddy dune valleys. Rewetted raised bogs are often populated en masse. Slowly flowing waters it inhabits backwaters and side creeks and riparian forest tümpel with heavy vegetation.
The four-spot often flies together with the great pitch dragonfly , the common rush damsel , the black darter and the autumn damsel and the blue-green damsel ; in marshland and moorland, it is the peat maiden and the little maiden instead .
The habitats of the quadrangle differ depending on the stage of development.
Larval habitat
The larvae prefer waters a few decimeters deep overgrown with reed beds . In the first stages, the animals are mostly in diving leaf vegetation . The further development stages are mainly benthic . The animals rarely dig into the peaty water floor, which is mostly made up of detritus , and live on the mud. The species prefers shallower water depths in low -oxygen waters, such as when there is vegetation with peat moss . However, it can also reach the imaginal stage on other sediments.
To lay their eggs, the females choose low-current or stagnant bodies of water that carry water all year round. The pH value is between 4 and 8.2, usually in the slightly acidic range. Here the four-spot also seems to have a clear ecological advantage over other dragonfly species, because it is the only species whose abundance does not generally decrease with increasing acidity, but even increases up to a certain threshold value. In addition, it can survive in brackish water up to a salt content of 7 ‰.
From the point of view of the water quality, the quadrangle settles in eu- or mesotrophic waters, i. H. These are waters with good nutrient content and visibility depths of two meters. The oxygen saturation decreases at the end of summer stagnation to values around 30%. The species also lives less often in oligotrophic waters, i.e. clearer waters with higher oxygen saturation and lower phosphorus content. The oxygen concentration is between 1.9 and 16.3 mg / l.
| Concentration in mg / l | |
| Ammonium (NH 4 + ) | <0.4 |
| Iron-II (Fe 2+ ) | 0-2 |
| Iron-III (Fe 3+ ) | 3 |
| Nitrate (NO 3 - ) | <0-200 |
| Nitrite (NO 2 - ) | <0-0.1 |
| Total phosphate | <0.057 |
The hydrochemical composition of the water in which the larvae live is as follows: The total hardness of the water, i.e. the concentration of the cations of the alkaline earth metals , is between one and ten ° dH . The carbonate, that is, the concentration of bicarbonate - anion (HCO 3 - ), is less than three ° dH. The conductivity of the water is between 30 and 270 µ S / cm. Concentrations of some other ions and compounds are given in the table on the right.
The absolute water temperature does not play a major role for the larvae of the quadrangle as long as there is an adequate supply of oxygen. It is more important that there are no major temperature fluctuations during the day. The height of the temperature affects the extent of the spots on the Nodus. It is also partly assumed that the differences used to describe subspecies can only be traced back to these temperature differences during larval development.
To hatch, the larvae climb plants sticking out of the water, so-called emersed vegetation . On average, they choose heights of several decimeters; but animals have also been found at a height of over two meters. Some larvae also seek hatching places several meters away from the water.
Imaginal habitat
Once the adults have hatched, these so-called youth morphs can be found in meadows , fields , heaths , vineyards , hedges and forest edges as well as in moors.
The sexually mature adults withdraw to rest up to 200 meters from the water and look for seats in the vegetation at a height of about half a meter. When reproducing, they prefer bodies of water surrounded by trees and forests, which on the one hand are free in the center - i.e. not overgrown - and on the other hand have species-rich vegetation on the banks. The vegetation of common habitats consists mostly of rushes , pond and swamp rushes , sedges , pond horsetail , reeds and cattails . The Vierfleck avoids bodies of water that are shaded by the surrounding trees. Exceptions are larger bodies of water, which still offer the animal a sufficiently sun-exposed sub-area. The depth of the populated waters is usually between ten centimeters and two meters. The water surface ranges between a few ares and a few hectares , but this dragonfly can also colonize smaller bodies of water such as garden ponds. The flow speed of the water is less than ten centimeters per second .
Way of life
food
The larvae feed primarily on small animals living on the bottom of the water, but also on small fish and tadpoles . If food is scarce , cannibalism can also occur. The adults, on the other hand, mainly feed on mosquitoes , but other flying insects are also preyed on .
Flight time and flight behavior
The first animals hatch in May, whereby in warm years the quadruple flies as early as the end of April. Depending on the climate, the hatching time extends into the beginning of June, in warm weather it can extend into July. The flight time ends in mid to late August. During the day, the quadrangle begins its flight regardless of the light conditions as soon as it is warm enough.
The Vierfleck is known to wander in flocks . These swarms can reach gigantic proportions. For example, the largest swarm observed over Germany on May 19, 1862, consisted of an estimated 2.4 billion animals (Moore 1960, quoted in). The trains also reach considerable expansions during their hikes. There are reports that mention 330 square kilometers, which means that the quadrangle also clearly exceeds the wandering dragonfly. The swarms usually form when the temperature suddenly rises after a cool spring, and they then gradually increase as individuals from other bodies of water join in a kind of herd instinct as they fly over. According to the current state of research, the animals do not come from a single body of water, as was previously assumed. Another trigger for migration may be a parasitic infestation with flukes of the genus Prosthogonimus , which “reprograms” the dragonfly. The resulting swarms are not species-specific, but mostly also have representatives of other species - for example the flat-bellied. In terms of numbers, however, these admixtures are negligible. The swarms that form rise to a height of less than 20 meters, but can reach a height of up to 30 meters. The migration can take up to seven days, with interruptions during the night. For orientation , the dragonflies probably prefer straight structures such as railways , canals and coastlines .
Reproduction and development
The pairing usually takes between three and 30 seconds and takes place in shaking flight. Then the female lays 2500 to 3500 eggs in a rocking flight by repeatedly touching the surface of the water with her abdomen. The eggs are protected by a transparent jelly shell and sink to the bottom of the water or stick to the underwater vegetation they happen to encounter. Another advantage of the gelatinous shell is that it is the ideal breeding ground for small algae that camouflage the eggs. They are approximately spherical, about 0.5 millimeters long and 0.43 millimeters wide. Their color is yellowish to white. As they develop, they turn yellow or orange-brown. As with the flat belly , the male guards the female until it has finished laying eggs.
The development of the embryos takes two to seven weeks, depending on the temperature. The subsequent larval stage is divided into twelve or more stages, not counting the prolarva stage . The period between two moults is variable and increases from moult to moult. The larva only needs one to two weeks for the first molt, but the later molt can be up to 72 days apart. Before metamorphosis , the larva can also overwinter in a diapause . The development time of the dragonfly is between two and three years.
- Vierfleck when hatching
After hatching, the dragonflies fly between two and 75 meters to a point where their chitin shell then continues to harden for about a day. The subsequent maturation period is twelve to 18 days. Then the males return to the water; the females follow a few days later. The maximum age of the adults is about 48 days.
Naming
Scientific names
Linnaeus provided the first scientific description of the species under the name Libellula quadrimaculata , which is still in use today and which he wrote as 4-maculata . In addition to the pterostigmata that occur in all dragonflies, the quadrangle has four more distinct marks on the wings, hence the name. The scientific name is derived from the Latin words quattuor and maculatus . Quattuor is a prefix and means four , maculatus can be translated as spotted . The actual description of the species is extremely short and reads:
“Alis posticis basi omnibusque medio antico macula nigricante”
The holotype on which the description is based was a male, came from Sweden and is now in the Natural History Museum . In 1781 it was Fabricius who gave a description under the name Libellula quadripunctata . In 1782 Moses Harris referred to the animal as Libellula maculata . Edward Newman (entomologist), on the other hand, called the dragonfly Libellula praenubila in 1833 . In the same publication, Newman raised another specimen to the generotype for the genus Leptetrum, which was later synonymous with Libellula . In 1839 Thomas Say describes a female and a male that he received from Harris under the name Libellula tenaria ; however, in his concluding remark on the species, he already considered the similarities to Libellula quadrimaculata :
"In some of its characters it resembles the L. quadrimaculata , Linn., Of Europe, but that has not the terminal wing bands."
In his “Synopsis of the Neuroptera of North America” in 1861 , Hermann August Hagen stated that the male was L. quadrimaculata , while the female was a Libellula semifasciata . Nothing is known about the whereabouts of the animals on which the works of Fabricius, Harris, Newman and Say are based. Robert McLachlan used the name Libellula (Orthetrum) basilinea for a male from China in 1894 . The specimen is now in the Natural History Museum. In 1957 Erich Schmidt downgraded L. quadrimaculata to the subspecies L. quadrimaculata quadrimaculata and introduced the additional subspecies L. quadrimaculata asahinai based on a male from Japan . Four years later, Schmidt added the subspecies L. quadrimaculata grigorievi based on a male from Afghanistan . Both copies are in the Schmidt collection .
Systematics
The four-spot is classified within the large dragonflies in the genus Libellula , a group that was created by Carl von Linné in 1758 and in which he included all dragonflies known at the time. Today this genus consists of around 30 species, all of which are distributed across the Holarctic. Within the genus, the quadrangle is described as the closest related to the North American Libellula semifasciata and the Japanese Libellula angelina . This is confirmed both by morphological (especially characteristics of the genital structure and wing veins) and by molecular biological characteristics. In the purely morphological view as a basal taxon, these three species stand in opposition to all other Libellula species (see cladogram), but in molecular biological studies they are classified within the Libellula species.
| Libellula |
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In Europe, in addition to the quadrangle, there are also the flat belly ( Libellula depressa ) and the pointed spot ( Libellula fulva ) within the genus Libellula . The generic affiliation of both species is, however, controversial; some authors place depressa in the genus Platetrum and fulva in the genus Ladona . Basically, Libellula can be viewed worldwide as a very heterogeneous genus for which a thorough revision is overdue.
literature
Different species names are listed in the brackets in front of the author.
Initial descriptions
- (4-maculata): Linnaeus, C. 1758. Systema Naturae. Per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. Tomus I. Laurentius Salvius, Holmiae. S. [1-4], 1-824.
- (4punctata): Fabricius, JC 1781. Species Insectorum, exhibentes eorum differentias specificas, synonyma auctorum, loca natalia, metamorphosin adiectis observationibus, descriptionibus. Tomus ICE Bohn, Hamburgi et Kilonii. Pp. I-VIII, 1-552.
- (maculata): Harris, M. 1782. An exposure of English insects. Including the several classes of Neuroptera, Hymenoptera, & Diptera, or Bees, Flies, & Libellulae. Exhibiting on 51 copper plates near 500 figures, accurately drawn, & highly finished in colors, from nature. White & Robson, London. Pp. 1-166, excl. pl. 1-50.
- (praenubila): Newman, E. 1833. Entomological notes (Continued). In: Entomological Magazine 1, p. 416.
- (teneraria): Say, Th. 1839. Descriptions of new North American neuropterous insects, and observations on some already described. In: Journal of the Academy of Natural Sciences of Philadelphia 8, pp. 9-46.
- (basilinea): McLachlan, R. 1894. On two small collections of Neuroptera from Ta-chien-lu, in the province of Szechuen, western China, on the frontier of Thibet. In: Annals and Magazine of Natural History (Series 6) 13: 421-436.
Secondary literature
- Arnett H. Ross, Jr. American Insects. A Handbook of Insects of America North of Mexico. CRC Press, Boca Raton Fla 2000, ISBN 0-8493-0212-9 .
- Jill Silsby: Dragonflies of the World. The Natural History Museum, Plymouth 2001, ISBN 0-565-09165-4 .
- Sternberg, K. (2000): Libellula quadrimaculata Linnaeus, 1758 - Vierfleck. Pp. 458-469. In: Sternberg, K. & R. Buchwald (eds.): Die Libellen Baden-Württemberg. Volume 2: Dragonflies (Anisoptera). Ulmer, Stuttgart, ISBN 3-8001-3514-0
- Gerhard Jurzitza: The Kosmos dragonfly guide . Franckh-Kosmos Verlags GmbH & Co., Stuttgart 2000. ISBN 3-440-08402-7 .
Secondary academic literature and articles
- AN Bartenef, 1930. On the aberrations of Libellula quadrimaculata L. (Odonata). In: Zoologischer Anzeiger. 87, No. 7/8, pp. 191-198.
- Wilhelm Blasius: About the large dragonfly trains through Northern Germany (Saxony, Braunschweig etc.) in the summer of 1881. In: 3rd annual report of the Association for Natural Science in Braunschweig for the association years 1881/82 and 1882/83. Braunschweig 1883, pp. 72-77.
- C. Brittinger, 1850. The dragonellulids of the Austrian Empire. In: Meeting reports of the Kaiser’s Academy of Sciences, Vienna s1 – s8.
- PS Corbet: Dragonflies, behavior and ecology of Odonata. Harley Books, Colchester 1999, ISBN 0-946589-64-X .
- H. Steinmann: World Catalog of Odonata. Volume II. Anisoptera. de Gruyter, Berlin / New York 1997, ISBN 3-11-014934-6 .
- JG Needham, 1901. Aquatic Insects in the Adirondacks. In: New York State Museum Bulletin. 47, pp. 383-612.
- RJS Musser, 1962. Dragonfly Nymphs of Utah (Odonata: Anisoptera). University of Utah Biological Series 12 (6): vii + 74 ff.
- EM Walker, PS Corbet 1975. The Odonata of Canada and Alaska. Volume 3. University of Toronto Press, Toronto 15 + 307 ff.
- BF Belyshev, (relicta) 1973. The dragonflies of Siberia (Odonata). Volume 1. Part 1 and 2. (Russian). Publishing House Nauka, Siberian Branch, Novosibirsk 1-620, figs. 1-270.
Web links
- Description and pictures
- Vierfleck in the nature lexicon
- Vierfleck under natur-in-nrw.de
- Libellula quadrimaculata inthe IUCN 2013 Red List of Threatened Species . Listed by: Dow, RA, 2010. Retrieved February 18, 2014.
Individual evidence
- ^ Hermann August Hagen - Synopsis of the Neuroptera of North America [p. 150], Smithsonian institution, 1861, books.google.de
- ↑ http://odonatacentral.bfl.utexas.edu/fieldguide/species.asp?taxaid=235 ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (March 1, 2007)
- ^ Thomas Say - Descriptions of new North American neuropterous insects. [S. 21]
- ↑ a b Mark Lung and Stefan Sommer: Libellula quadrimaculata. In: isu.edu. Retrieved March 1, 2007 .
- ↑ Ethan Bright and Mark F. O'Brien: Libellula. (No longer available online.) In: UMMZ-Insect Division. Archived from the original on May 26, 2010 ; Retrieved March 7, 2007 . 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.
- ^ L. Watson and MJ Dallwitz: Libellula quadrimaculata. In: British insects: the Odonata (dragonflies and damselflies) Version: 5th October 2005. Retrieved 9 March 2007 .
- ↑ a b c Robert, Paul-A .: Die Libellen (Odonaten) - Authorized translation by Otto Paul Wenger [p. 284ff], Kümmerly & Frey, Geographischer Verlag, Bern 1959
- ^ A b c Lucas, William John .: The Aquatic (Naiad) Stage of the British Dragonflies (Paraneuroptera) [p. 67ff], The Ray Society , London 1930
- ↑ a b c d e f g h i j Klaus Sternberg, Rainer Buchwald: Die Libellen Baden-Württemberg. Volume 2: Dragonflies. Eugen Ulmer, Stuttgart 1999, 2000, ISBN 3-8001-3514-0
- ^ Valle, KJ: The distribution of the Ostfennoskandinavischen Odonaten [p. 43], Helsinki 1952
- ↑ German Youth Association for Nature Observation (DJN), Lehmann, Arne: Libellen Nord- und Mitteleuropas. Standard work for the determination of all dragonfly species in Northern and Central Europe. 5th edition, 1998 ISBN 3-923376-15-4 naturbeobachtung.de
- ^ Henrik Steinmann: World Catalog of Odonata. Volume II: Anisoptera. de Gruyter, 1997, ISBN 3-11-014934-6 , p. 395 f.
- ^ Frank Louis Carle, Karl M. Kjer: Phylogeny of Libellula Linnaeus (Odonata: Insecta). In: Zootaxa. 87, 2002; Pp. 1-18.
- ↑ Thomas Artiss, Ted R. Schultz, Dan A. Polhemus, Chris Simon: Molecular Phylogenetic Analysis of the Dragonfly Genera Libellula, Ladona, and Plathemis (Odonata: Libellulidae) Based on Mitochondrial Cytochrome Oxidase I and 16S rRNA Sequence Data. In: Molecular Phylogenetics and Evolution. 18, No. 3, 2001; Pp. 348-361.
