Helophorus aquaticus
| Helophorus aquaticus | ||||||||||||
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Helophorus aquaticus on reed leaf |
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| Scientific name | ||||||||||||
| Helophorus aquaticus | ||||||||||||
| ( Linnaeus , 1758) |
Helophorus aquaticus is a beetle fromthe water beetle family and the subfamily Helophorinae . The genus Helophorus is represented in Europe with eight subgenus , Helophorus aquaticus belongs to the subgenus Helophorus , which is represented in Europe with seven species.
In Reitter's "Fauna Germanica" document, synonyms are used which cause confusion. Under the name " Helophorus aquaticus L." the species Helophorus grandis Ill. is described there, the species described here is listed by Reitter together with other species as a variant "v. aequalis ". Furthermore, it was only proven in 1982 that Helophorus aquaticus stands for two species whose karyograms differ significantly and which cannot be crossed, namely Helophorus aquaticus and Helophorus aequalis . In the case of literature references and lists of where they were found for Helophorus aquaticus, you must carefully check whether they really refer to Helophorus aquaticus .
The generic name Helophorus from ancient Greek ήλος 'hēlos' 'nail, hump' and φωρῶς 'phorós' 'bearing' names the elevations on the pronotum. The species name aquaticus from Latin aquāticus means 'living in water' and refers to the beetle, not the larva. The common German name for the species-rich genus is 'Furchenwasserkäfer'.
  
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| Fig. 2: Head and breast shield | Fig. 3: Penis | |
 
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Fig. 1: View from below, side and front |
Fig. 4: End of the abdomen from below above: H. grandis below H. aquaticus |
Fig. 5: jaw feeler |
Characteristics of the beetle
The four to six millimeter long beetle is dark yellow-brown, but the color is often falsified by pollution. The females are on average a little longer than the males. When viewed from above, the beetle is elongated oval and when viewed from the side it is flat below and arched above (Fig. 1).
On the top of the head there is a large and deep groove in the shape of a Y (Fig. 2). The four-section jaw probes with a very small base section protrude far beyond the outline of the head. Your last link is not symmetrical to the longitudinal axis, but the inside is almost straight, while the outside is clearly curved outwards (Fig. 5). The upper jaws are short and curved. They end in a point and have a small pointed tooth on the inside. The nine-part antennae are deflected on the underside of the head. The two strong base links are followed by three narrow antenna links and one link that widens outwards and hugs the club. The antennae end in a three-part club, the limbs of which appear dull due to the hair.
The species of the genus are easily recognizable by five longitudinal furrows on the pronotum . In Helophorus aquaticus the gaps are evenly coarse and completely granulated, the grains are partially connected. The inner bulges next to the central longitudinal furrow are shiny (Fig. 2).
The wing covers have clear rows of coarse points . The spaces between the rows of dots are almost flat and not alternately flat and arched (Fig. 1 below). The row of dots next to the wing cover seam branches off near the base. The resulting greatly shortened row of dots is called a scutellar stripe. Only a part of the species of the genus has a scutellar streak. The wing covers usually have a few lighter spots.
The rear edge of the last abdominal sternite is concise, but not crenellated, with clear jagged gaps as in the larger Helophorus grandis (Fig. 4). The male aedeagus is shown in Fig. 3. It narrows upward more than in Helophorus aequalis . In the female, the “tips” of the horseshoe-shaped ninth tergite are not bent outwards.
The legs are rather weak. Fore and middle tarsi are four-limbed, the hind tarsus five-limbed. The claw links are long, but the claw link of the hind tarsi is significantly shorter than the other four tarsi together.
larva
The elongated larva has nine fully developed abdominal segments and two long tripartite abdominal appendages. In the third stage it reaches a head width of 0.85 to 0.9 millimeters.
The front edge of the head has a triangular extension (nasal) in the middle, on both sides of which there is a forward-facing lobe-shaped extension, on the front edge of which there are five inwardly curved bristles.
Each abdominal segment has two dorsal and two dorsolateral sclerites on the upper side, symmetrical to one another, and two small point-shaped sclerites on both sides. The smaller of these lies in front of the dorsoventral sclerite, the larger still further in front and further inside. There are two lateral sclerites on each side. Ten sclerites sit on the underside, two of which are arranged medially one behind the other, the others symmetrically on both sides. On the upper side of the dorsolateral sclerite there is a breathing opening which is significantly smaller than the larger punctiform sclerite.
The pairs of legs on the three chest sections are rather weak.
biology
The beetle lives in standing or slowly flowing small bodies of water and temporary micro bodies of water (wagon tracks, puddles, rain barrels, ditches), preferably in montane locations . The species is classified as a pioneer species in waters with a sandy and clay bottom (silicophil) as well as in floodplains and floodplain areas (stepophil). In Spain the species was found at an altitude of over 1300 meters. An investigation in Hungary showed a very clear maximum flight activity in the late morning.
The adults are harmless herbivores, they feed on decaying plant substances and thread algae, but in the laboratory they do not disdain dry peas either. The larvae live in the mud and feed on small insects. They can be fed Tubifex while breeding .
The species overwinters as an imago , occasionally as a larva. Overwintered adults appear in March and lay their eggs in April and May. The eggs are laid in a cocoon made of silk threads. This consists of a pocket and a narrow extension, which is reminiscent of the leaf blade of a sweet grass and which stands over the pocket like a mast or chimney. The bag contains an egg packet. The cocoon is pushed into the mud on the bank. If the oxygen supply through the fabric of the bag is cut off due to sludge deposits or rising water levels, the oxygen supply takes place via the chimney. The larva hatches after about a week at room temperature. The species only needs about two weeks for the subsequent development, with three larval stages going through. To pupate, the larvae build a pupal chamber. Freshly hatched animals appear from mid-June. Sexual maturity is only reached after several months.
distribution
The distribution area stretches from Portugal , Spain and Italy and the islands of the western Mediterranean north to Finland . The eastern border runs through Austria , Hungary , Germany , Poland and the Baltic states and leaves out the Czech Republic and Slovakia . In the west there are no find data from Great Britain and Ireland . The species is also reported from European Turkey , the Middle East and parts of Asia.
literature
- Heinz Joy, Karl Wilhelm Harde, Gustav Adolf Lohse: The beetles of Central Europe . tape 3 . Adephaga 2 - Staphylinoidea 1. Goecke & Evers, Krefeld 1971, ISBN 3-87263-015-6 .
- Edmund Reitter : Fauna Germanica, the beetles of the German Empire, Volume II, KGLutz 'Verlag, Stuttgart 1909
- Gustav Jäger (Ed.): CG Calwer’s Käferbuch . K. Thienemanns, Stuttgart 1876, 3rd edition
Individual evidence
- ↑ a b Helophorus aquaticus at Fauna Europaea. Retrieved April 6, 2012
- ↑ Helophorus at Fauna Europaea. Retrieved April 3, 2012
- ↑ a b Edmund Reitter : Fauna Germanica, the beetles of the German Empire, Volume II, KGLutz 'Verlag, Stuttgart 1909 p. 347
- ^ Heinz Joy, Karl Wilhelm Harde, Gustav Adolf Lohse: Die Käfer Mitteleuropas . tape 3 . Adephaga 2 - Staphylinoidea 1. Goecke & Evers, Krefeld 1971, ISBN 3-87263-015-6 . Comment p. 118
- ↑ RB Angus: "Separation of two species standing as Helophorus aquaticus (L.) (Coleoptera: Hydrophilidae) by banded chromosome analysis" Systematic Entomology Volume 7, Issue 3, pages 265-281, July 1982 doi: 10.1111 / j.1365- 3113.1982.tb00444.x .
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names.
- ↑ a b Determination table for the genus Helophorus from Coleo-net, accessed April 4, 2012
- ^ A b c d e f RB Angus: "The habitats, life histories and immature stages of Helophorus F. (Coleoptera: Hydrophilidae)" Transactions of the Royal Entomological Society of London Volume 125, Issue 1, pages 1-26, June 1973 doi: 10.1111 / j.1365-2311.1973.tb00535.x .
- ↑ a b Lars Hendrich: Red list and total species list of the water beetles of Berlin (Coleoptera: Hydradephaga, Hydrophiloidea part., Staphylinoidea part., Dryopoidea part.) THE STATE REPRESENTATIVE FOR NATURE CONSERVATION AND LANDSCAPE MAINTENANCE / SENATE ADMINISTRATION FOR URBAN DEVELOPMENT: Rote MAINTENANCE MANAGEMENT FOR URBAN DEVELOPMENT Plants and animals from Berlin as PDF ( memento of the original from January 2, 2014 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.
- ↑ LFValladares: Los Palpicornia acuáticos de la Provincia de Leon. III. Helophoridae, Hydrochidae, Hydrophilidae (Coleoptera) Boln.Asoc.esp.Ent., 19 (1-2): 1995 pp. 281-308 ISSN 0210-8984 as PDF
- ↑ Zoltán Csabai et al .: A "polatisation sun-dial" dictates the optimal time of day for dispersal by flying aquatic insects Freshwater Biology (2006) 51, 1341-1350 doi: 10.1111 / j.1365-2427.2006.01576.x as PDF ( 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.
