Nemouridae
| Nemouridae | ||||||||||
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| Nemouridae | ||||||||||
| Newman , 1853 |
The Nemouridae are the most species-rich family of stoneflies . It includes almost 400 species in 17 genera. The Nemouridae are distributed over the entire northern hemisphere ( Holarctic ), in the southern hemisphere they are replaced by the similar family Notonemouridae . The family is divided into the subfamilies Nemourinae and Amphinemurinae . Important genera, also rich in species in Europe, are z. B. Nemoura , Protonemura , Amphinemura , all of these genera are distributed worldwide with a total of almost 100 species. As another European genus, Nemurella is widespread with the only species Nemurella picteti .
features
Nemouridae are relatively small, mostly not very contrasting and darkly colored stoneflies, the abdomen is often reddish brown in color. The wings are often darkly clouded, sometimes spotted, and are spread flat on the abdomen at rest. The most striking feature of the family is a special structure of the wing veins: a diagonal cross vein on the wing leading edge results in a distinctive x-shaped structure on the fore wing. However, this characteristic is not entirely reliable because it occasionally occurs in representatives of other families. The Nemouridae have short, single-limbed cerci that never develop long tail threads. In the males, they are part of the complicated copulation apparatus, which takes up the entire rear end and whose special structures are usually the only characteristic for reliable species identification; many females are therefore not determinable down to the species.
At the head, the last segment of the labial palp has expanded into a flat, round structure. The mandibles and maxillae are relatively wide, they are used by the animals to obtain food, which is done by scraping off vegetable matter, mostly algae or partially decomposed detritus. The three segments of the thorax are about the same size, the prothorax is rectangular and covered with hair and short thorns on top. The second tarsal segment of the legs is always significantly shorter than the first. The end of the abdomen of the males has intricately built mating organs. In females, the stomach plate (sternite) of the seventh segment is usually extended backwards and forms a subgenital plate.
The adults of most species are able to fly, but not very active in flight and can usually be found near the larval waters. When disturbed, they often drop and try to dive into the tangle of plants rather than fly away. The North American genus Nanonemoura is wingless.
Larvae
The body shape of the larvae of the Nemouridae is very similar to the imagines, only that wings and mating organs are missing and there are always two elongated tail threads (the cerci) at the end of the abdomen. In the neck region (cervical region) behind the head, there are distinctive tubular (e.g. protonemura ) or tufted gills (e.g. amphinemura ) in some genera , which are very characteristic of the respective genus. The gills are usually still clearly recognizable on the adults as shrunken gill rudiments. The wing systems of the larvae are designed as rigid wing sheaths, which, as a rule, protrude obliquely backwards in a characteristic shape in all species of the family. The body appears relatively compact, not as elongated as that of the related families Leuctridae and Capniidae . There are usually strong, thorn-shaped bristles on the entire body, but especially on the femora of the legs, but they can also be missing.
Ecology and way of life
Nemourid larvae are typical inhabitants of cold, clear streams ( Rhithral ) and springs ( Krenal ). In contrast, they are largely absent in rivers ( Potamal ). Only a few genera and species live in stagnant waters, including the ubiquist Nemoura cinerea , which is one of the few species of stone flies that can colonize more polluted waters. Mountain streams are particularly populated with a large number of species, in which thirty species can easily occur next to each other, although their larval stage is so similar that they cannot be identified. Many species are endemic to mountains, e.g. B. seven species in the Alps and fifteen in the Pyrenees. The lowland regions usually have no species that are unique to them.
Nemourid larvae live on the bottom of the water, on gravel or stones or on fallen leaves. Only a few species are more common on soft substrates such as sand or on aquatic plants. Most species grate organic matter such as B. Fall foliage ("shredder"), or they collect finer particles from the bottom, few graze the ( biofilm ) of algae and microorganisms on the surface of stones.
The larval development of the Nemourids usually takes one year (monovoltine). In the far north, some species need two years (semivoltin).
Fossils
Animals with the characteristics of the recent family, but some plesiomorphies such as B. tripartite cerci, are in excellent condition from Siberia and Inner Mongolia (China). For them, a family Protonemouridae (not to be confused with Protonemurinae, without o!) Was established , which should form the parent group of the Nemouridae and Notonemouridae. There are both fossil adults and larvae, most of which correspond to the more recent forms. The line of development of the family is therefore certainly Mesozoic in old age, presumably Jurassic .
literature
- Richard W. Baumann (1975): Revision of the Stonefly Family Nemouridae (Plecoptera): A Study of the World Fauna at the Generic Level. Smithsonian contributions to zoology Number 211.
- Peter Zwick: Plecoptera (Perlaria, bank flies). Handbook of Zoology, A Natural History of the Tribes of the Animal Kingdom. Delivery 26. Verlag Walter de Gruyter; 2nd edition 1980. ISBN 3-11-008141-5 .
- Graf, W., Lorenz, AW, Tierno de Figueroa, JM, Lücke, S., López-Rodríguez, MJ, Murphy, J. & Schmidt-Kloiber, A. (2007): Plecoptera Indicator Database. Euro-limpacs project, Workpackage 7 - Indicators of ecosystem health, Task 4, www.freshwaterecology.info, version 5.0 (accessed on January 4, 2012).
Web links
Individual evidence
- ↑ RW Baumann & GR Fiala (2001): Nanonemoura, a new stonefly genus from the Columbia river gorge, Oregon (Plecoptera, Nemouridae). Western North American Naturalist 61 (4): pp. 403-408.
- ^ ND Sinitshenkova (2005): The Oldest Known Record of an Imago of Nemouridae (Insecta: Perlida = Plecoptera) in the Late Mesozoic of Eastern Transbaikalia. Paleontological Journal, Vol. 39, No.1: pp. 38-40. (Translated from Paleontologicheskii Zhurnal, No. 1, 2005, pp. 39-41.)
- ↑ Liu Yushuang, Nina D. Sinitshenkova, Ren Dong, Shih Chungkun (2011): Protonemouridae fam. nov. (Insecta: Plecoptera), the stem group of Nemouridae and Notonemouridae, from the middle Jurassic of Inner Mongoloia, China. Palaeontology, Vol. 54, Part 4: pp. 923-933.