Dryops ernesti
| Dryops ernesti | ||||||||||||
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Dryops ernesti |
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| Dryops ernesti | ||||||||||||
| ( des Gozis , 1886) |
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| Fig. 1: Front view | Fig. 2: side view |
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| Fig. 3: Bottom | Fig. 4: Double hair on the left: above the eyes on the right: back third of the wing cover |
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| Fig. 5: Feeler, left: stretched out, middle: inserted into the feeler pit, right: copy of the middle picture partially tolerated green: eye, red: outline of the feeler pit gray: 1st antennae, blue: 2nd antennae, yellow: antennae lobe |
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Dryops ernesti is a beetle from the hook beetle family. The beetles of the species Dryops ernesti are usually not distinguished from the other species of the genus Dryops by a two-part German name, but, like the entire family Dryopidae, only assigned the German name hook beetles . However, the name Ernests hook beetle, which is already used occasionally, lends itself to
The name "hook beetle" refers to the hook-shaped feelers. The species name ernesti ( Latin ) honors the coleopterologist Ernest Olivier. The generic name Dryops ( old Gr . Δρύωψ) designates various people in Greek mythology. The genus Dryops is represented in Europe with twenty species. The species of the genus are very similar and can only be reliably differentiated with the help of genital examinations .
Physique of the beetle
The hook beetle Dryops ernesti reaches a body length of 3.8 to 4.5 millimeters. The beetle is doubly hairy. The short, lying basic hair covers the whole body. It is fine and dense, but lets the dark base color shine through clearly. The coarser main hair on the upper side of the body is long and, in contrast to most Central European species of the subgenus Dryops, erect (Fig. 4). The body is less elongated and more arched in cross-section than the body of Dryops striatellus .
The head is drawn back up to the eyes in the pronotum . The large eyes are rounded and, compared to other beetles, are made up of relatively few and large individual eyes . They are densely covered with stiff hair. The mouthparts point downwards. The upper jaws do not protrude beyond the upper lip. The construction of the short antennae is characteristic of the whole family. The first antenna segment is short and strong, the second widened ear-shaped and drawn out to a blunt point in Dryops ernesti . The remaining seven antenna elements form a spindle-shaped, pointed club that is bluntly sawn on the inside. The feelers can be inserted into a feeler pit under the eyes and then blend into the outline of the head so that they can hardly be recognized (Fig. 5).
The pronotum has a clear longitudinal groove on both sides, the outer edge of which is sharply edged. In Dryops ernesti , the edges of the longitudinal grooves at the base of the pronotum move slightly away from each other. The side edge of the pronotum is slightly rounded in front of the base and then narrowed in a straight line towards the front. At the base, the pronotum is hardly narrower than the elytra .
The elytra are less parallel than in Dryops striatellus . At the back they are rounded off together in all species of the genus. In Dryops ernesti they are irregularly dense and roughly dotted , at the base the dots can be arranged in the form of five to six rows of dots.
The underside of the body is slightly arched. The front chest is extended backwards and engages in a pit in the mid-chest. The front hip cavities are open to the rear. The cylindrical front hips are approximately perpendicular to the body axis. The middle hips are closer to the front hips. The rear hips are slightly hollowed out towards the rear so that they can accommodate the front of the hind legs. The tarsi are all five-limbed, the claw limb is noticeably long and strong. Because of this property, the families Dryopidae and Elmidae were formerly combined as claw beetles. The abdomen has five visible abdominal plates.
The basal part of the male genital organ is curved downwards and sclerotized to the same extent as the aedeagus . In contrast to the subgenus Ydrops, the membrane sac of the Aedeagus has a ventral ridge which in Dryops ernesti is not in three parts . In Dryops ernesti, the penis only has a very finely structured surface. The females have a spike-shaped two-part laying stinger .
Construction of the larva
The red-yellow larva is elongated and cylindrical and is reminiscent of wireworms , the larvae of click beetles .
The seams between the individual chitin plates are clearly visible on the head capsule. There are six point eyes on each side of the head . There is a pair of point eyes near the forehead, a group of three point eyes lower and further in front, and a sixth point eye on the underside of the head. The antennae are short and tripartite. The basal segment is by far the largest, the second segment a good half as long and thick as the basal segment. The third link consists of two parallel sections. The inner section is about the same length and half as thick as the second link, the outer section is about the same thickness but less than half as long as the inner section. The strong upper jaws are little and indistinctly toothed. The lower jaws have short four-part jaw probes . Her two stores, Galea and Lacinia, are membranous and hairy. The Galea towers over the Lacinia and reaches forward over this inward. Both are equipped with strong thorns on the inside. The lower lip is roughly rectangular and very wide, with two short, two-part lip buttons on the side .
The three chest sections each have a pair of short and strong legs that end in a firm claw. They indicate a digging way of life. The pair of spirals of the eighth abdominal segment lies dorsally.
The exit of the intestinal tract on the ninth (last) abdominal segment is covered by an oval chitin plate, the operculum. To the side of it there are two short anal appendages.
Construction of the doll
The pupa is elongated, membranous and hairy. There is an unpaired appendix ( terminal thread ) dorsally on the ninth (last) abdominal segment . On the second to the seventh abdominal segment there is a small lobe-shaped bulge (gin-trap) on the back near the following segment. Only the tip of the cercie and the toothed edge of the gin-traps are sclerotized . The species of the genus are also very similar in the formation of these dimensionally stable parts.
Way of life
The beetles are counted among the water beetles, even if Dryops ernesti is not bound to water. The thick hair prevents wetting of the body. The beetles cannot swim and only move slowly when they crawl. The body is in an air bubble. When the beetle loses contact with the substrate, it is carried to the surface of the water like a cork, from where it can be blown up. Oxygen is absorbed through the air bubble into which the oxygen dissolved in the water diffuses and through the absorption of oxygen bubbles that plants produce during photosynthesis by means of the mouthparts. This allows the beetle to stay underwater indefinitely. The beetles are herbivores. The eggs are released into plant tissue with the laying stinger. The larvae are not only found in the water, but have also been observed gnawing the roots in corn and cereal fields. In any case, they leave the water to pupate.
distribution
The species is widespread in Europe, even if no data is available from some countries. It is common and can be found from the plains to the high mountains. It is mainly found in the flushing fringes of standing water, but also in damp moss, in fields and occasionally in flowing water.
swell
- Heinz Joy, Karl Wilhelm Harde, Gustav Adolf Lohse: The beetles of Central Europe . tape 6 : Diversicornia . Spectrum, Heidelberg 1979, ISBN 3-87263-027-X .
- Wolfgang Engelhard: What lives in pools, brooks and ponds? Kosmos, Franckh'sche Verlagshandlung, Stuttgart 1955.
- Henri PI Bertrand: Larves et Nymphes des Coleoptères aqatiques du Globe. Imprimerie Paillard, Paris 1972.
Individual evidence
- ↑ a b Fauna Europaea
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (species)
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (genus)
- ^ Dryops at Fauna Europaea. Retrieved March 18, 2013
