Mutable edible scratch beetle

Mutable edible scratch beetle
Variable pear beetle ♂
Systematics
Class : Insects (Insecta) Order : Beetle (Coleoptera) Subordination : Polyphaga Family : Scarab beetle (Scarabaeidae) Subfamily : Rose chafer (Cetoniinae) Type : Mutable edible scratch beetle
Scientific name
Gnorimus variabilis
( Linnaeus , 1758)

The mutable pear beetle ( Gnorimus variabilis , formerly eight-point pear beetle, Gnorimus octopunctatus ) is a beetle from the subfamily of rose beetles (Cetoniinae) in the family of scarab beetles (Scarabaeidae). The genus Gnorimus is represented by three species in Europe . The rare species is listed in the Red List of Endangered Animals in Germany under Category 1 (threatened with extinction) and is strictly protected in Germany . In the federal states, the beetle is usually classified as endangered or critically endangered . Females and males clearly differ from one another in several external features.

Notes on the name

The beetle was described by Linnaeus as the 53rd species of the genus Scarabaeus under the name Scarabaeus variabilis as early as 1758 in the famous 10th edition of his Systema Naturae , which is the starting point of the binomial nomenclature . The description begins with the words Scarabaeus muticus laevis opacus ater, elytris punctatis ( Latin truncated Scarabaeus, hairless, matt black, with dotted elytra). The description, which is unusually detailed for Linné, ends with the statement that the beetle varies in color, gold and red (variat colore aureo & rubro). This remark explains the species name variabilis (Latin for changeable) that Linnaeus gives the beetle. But it is based on an oversight. In describing variabilis, Linné refers to a panel by Rösel von Rosenhof . 4 shows a red and gold variant of nobilis . Linné describes the next type of Scarabaeus as the type nobilis . He is referring to the same panel by Rösel, and in a later Dutch translation of his father-in-law's work, Kleemann adds the description of the above-mentioned panel, Fig. 1 to 5, (the depicted animal is called the second variety of gold beetle by Roesel ) the footnote that Linnaeus named this beetle nobilis . In addition to nobilis , only figure 6 shows the beetle Osmoderma eremita , which Rösel calls the large black-brown beetle . This beetle, however, is dark brown and unpotted, which contradicts the first sentence of Linné's description of variabilis . Variabilis is therefore not shown by Rösel and has no red and gold variants. In the following editions of the Systema naturae the error in the description of variabilis is retained, in the 13th edition under the Cura of Gmelin the color variance is further cited, but there is no reference to Rösel's plate, while the plate is mentioned in nobilis becomes. The mixing of the two species variabilis and nobilis as variants of the same species can still be found in 1783 in Herbst, who suspected that the black and the shiny gold-green species ... are the same beetle . In later authors, however, the species is described exclusively as a black beetle.

In 1775, Fabricius describes a variant of the species with eight points: with two points each on the pronotum, each wing cover and the pygidium. He lists them as the eighth species of the genus Cetonia under the name Cetonia 8-punctata (lat. Eight-point Cetonia ). Therefore, in the genus Gnorimus, the epithet octopunctata is a synonym for variabilis .

The large genus Scarabaeus von Linné is split up, the affiliation to Cetonia is recognized as wrong. Later authors put the species in the genera Melolontha , Trichius , Aleurostictus and Gnorimus . In Opinion 2186, in 2007 the International Commission for Zoological Nomenclature suppressed the genus name Aleurostictus Kirby 1827 in favor of Gnorimus Le Peletier & Serville 1828 because the supposedly newer name is more common. The commission thus corresponds to the application of Case 33549. This is incorrect in so far as Le Peletier and Serville published the name Gnorimus when dividing the genus Trichius as early as 1825, before Kirby, as other authors also note. Le Peletier and Serville place Trichius variabilis in the one subdivision they call Gnorimus .

The generic name Gnorimus from ancient Greek γνώριμος, 'gnōrimos' means 'known, famous'.

Characteristics of the beetle

Fig. 1: Top view ♀			Fig. 2: Front view ♂
Fig. 3: Side view ♀
Fig. 4: Bottom ♂			Fig. 5: Bottom ♀
Fig. 6: Upper jaw from inside and above		Fig. 7: Lower jaw with jaw probe		Fig. 8: Lower lip with lip switch
Fig. 9: Front rail		Fig. 10: Middle rail		Fig. 11: Hind leg
Fig. 12: Detail of the abdomen ♂			Fig. 13: Head shield

The black, not very shiny beetle with yellowish to whitish spots becomes 17 to 22 millimeters long. The female is on average slightly larger than the male. The beetle is hairless on top.

The dense and finely wrinkled dotted head (Fig. 2) points forward with the mouthparts (prognath). The quadrangular head shield is bordered at the front and there, especially towards the sides, is stronger in the male, but hardly bent up in the female (Fig. 13). The upper jaws (Fig. 6) are hidden under the head shield. The outer, only slightly horny part is pointed and slightly curved inward. It clearly towers above the inwardly adjoining membranous part. At the base, opposite the joint head, there is a large, grooved molar (top view on the left in Fig. 6). The inner drawer of the lower jaw protrudes beyond the outer drawer and is covered with long hairs at the tip, which form a dense brush (Fig. 7). The jaw probes are four-parted, the end part is as long as the previous three and is slightly curved (Fig. 7). The lower lip is cut very deeply (Fig. 8). The end link of the tripartite lip stylus is elongated ovoid (Fig. 8). The ten-segment antennae are brown-black. The last three links are drawn out to the front to form a lamella and form a narrow, elongated club that can be spread like a fan (taxo picture). This is only slightly longer in the males than in the females. The laterally protruding eyes are divided horizontally in front by a short forehead strip.

The pronotum is also very dense, dotted with cross wrinkles on the sides. Usually a central longitudinal line that is smooth at the back is indicated (Fig. 1, taxo picture). To the rear, the pronotum widens slightly bulbous and reaches its greatest width at four seventh of its length, then it narrows slightly and merges into the base via strongly rounded rear corners. This is about twice as wide as the front edge of the pronotum, broadly convex in the middle and slightly concave on the sides. The pronotum is edged, distinct on the sides, weak in front, the edge disappears towards the middle of the base. In the back corners there is usually a pale yellow to white spot.

The label is obtuse triangular to semicircular, dotted at the base, smooth behind.

The elytra are significantly wider than the pronotum and about twice as long as this. Together they are almost as wide as they are long. They are flat, gape at the back and leave the end of the abdomen uncovered. The shoulders are pronounced, and the wing covers are laterally bulged before the fall. They are dotted with wrinkled leather, stripes can be simulated. The elytra each usually have four or five small blemishes of the same color as the spots on the pronotum. The number, size and arrangement of the blemishes vary, however, and they can also flow together to form a large pale yellow spot.

The domed, truncated pygidium also has yellowish white spots, which can also be missing. It ends in two adjacent cusps, which are hardly developed in the male, but clearly developed in the female and are also visible from below (Fig. 5). The tip of the abdomen is short and finely hairy in the male.

The beetle is glossy black on the underside, the abdomen can be spotted white on the sides. The underside is long yellow-gray on the chest in the males, short old haired in the females (Fig. 4 and 5), the hair on the abdomen is sparse. The rear breast is clearly longitudinally furrowed in the middle, the furrow continues as a narrow groove over the first abdominal sternite in the male (Fig. 4 and 12), but not in the female (Fig. 5). The hind hips are brought closer together. The front rails specialize in digging. They have two pointed teeth on the outer edge, the outer one of which is at the end of the rail. These teeth are stronger in the female than in the male (Fig. 9). There is a movable mandrel at the top of the inside of the front rails. The easiest way to differentiate between the sexes is by the construction of the center rails (Fig. 10). In the female these show no special features, in the male they are slender at the base and strongly curved both upwards and outwards, after which they widen significantly. The tarsi of all legs are five-limbed, the first four, roughly the same length limbs, have a tuft of bristles on the underside towards the tip. The hind tarsi are significantly longer in the male than in the female (Fig. 11).

egg

The eggs are yellow-brown, almost spherical. Their longer diameter is about two millimeters, the shorter 1.8 millimeters.

larva

Larva, pictures after Perris, 1864
Fig. 14: Larva	Fig. 15: Upper jaw	Fig. 16: Lower jaw	Fig. 17: Sensor

The larva (Fig. 14) becomes about 23 millimeters long in the last stage. It is white with two reddish brown spots on the prothorax. It has the shape of a grub, is wrinkled and covered with very short, reddish hair, except on the head, fairly regularly. Especially on the back and under the 13th segment, these hairs are spiky. The head is almost as wide as the body, shiny reddish. It has a transverse groove on its forehead and several smaller bumps on the front edge. The epistome is wider than it is long and square. It has two dimples at the front, the front corners are slightly raised. The upper lip is semicircular, at the top it has an elevation. This is bordered by a kind of furrow parallel to the front edge, which is equipped with reddish and silky hairs. The reddish upper jaws (Fig. 15) are long, strong, only slightly curved. They have three teeth on the inside at the dark tip, their size decreasing towards the back. The lower jaws (Fig. 16) are broad and short, the ark is conical and decorated in the upper part with bristles and small spines, with a horny thorn at the tip. The four-part jaw buttons (Fig. 16) are inclined slightly inwards. The last two links are about the same length, the second link a little shorter, the first link very short. The square lower lip is short, and two stiff bristles sit between the two-part lip buttons. The antennae (Fig. 17) are five-limbed, the base limb is slightly shorter, but thicker than the others. The following three links are about the same length, the fourth link is enlarged at the tip to a kind of blunt spur. The distal phalanx is longer than the others, slightly narrower and sloping outwards and jagged inside. The body has thirteen links, the top is strongly curved, the bottom almost flat and the same thickness everywhere except at the narrower end. The three breast segments each carry a pair of legs. The hairy legs are four-limbed. The breathing openings are on the side, one near the front edge of the front chest, the other near the front edge of the first to eighth abdomen segment. They are horseshoe-shaped, with the opening facing back in the first segment and forward in the others.

biology

The beetle develops in old hollow trees or in lying strong branches, mostly from deciduous trees, especially in old oaks and chestnuts . It can be found in sparse deciduous forests and on the edges of forests, but as a fully developed animal it spends most of its time in tree hollows.

The beetles need two years to develop, and longer in cold areas. The larvae feed on sludge in tree hollows. The last larval stage overwinters and pupates in spring. The doll's cradle consists of feces and sludge. The adults appear in late spring. The beetles can be found in the Mulm from June to August, occasionally also on blossoms ( elder and umbelliferae ) or on tree sap that is flowing out. Soon after, mating and oviposition begins. For this purpose, the females dig themselves deep into the sludge. Then the beetles die.

distribution

The species is mainly found in northern southern and central Europe, but rare everywhere. The distribution area extends to southern Northern Europe. In the UK , the beetle is considered endangered. The beetle can also be found in the Middle East. There are no reports from Portugal or European Turkey .

literature

• Heinz joy , Karl Wilhelm Harde , Gustav Adolf Lohse (ed.): The beetles of Central Europe . tape 8 . Teredilia Heteromera Lamellicornia . Elsevier, Spektrum, Akademischer Verlag, Munich 1969, ISBN 3-8274-0682-X , p. 364 .
• Klaus Koch : The Beetles of Central Europe Ecology . 1st edition. tape 2 . Goecke & Evers, Krefeld 1989, ISBN 3-87263-040-7 , pp. 380 .
• Gustav Jäger (Ed.): CG Calwer’s Käferbuch. K. Thienemanns, Stuttgart 1876, 3rd edition, pp. 272f.

Web links

• Species sheet of the ARGE SWD coleopterologists
• Species gallery
• Nature in North Rhine-Westphalia
• Nature lexicon
• Species profile
• French side
• Spanish side

Commons : Mutable Edelscharrkäfer  - Album with pictures, videos and audio files

Individual evidence

1. ↑ ^{a b} Gnorimus variabilis in Fauna Europaea. Retrieved September 1, 2012
2. ↑ Gnorimus at Fauna Europaea. Retrieved February 20, 2012
3. ↑ Red List of Endangered Animals in Germany (Binot et alt. 1998) Archived copy ( Memento of the original from March 1, 2016 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. 
4. ↑ Alage 1 on the Federal Species Protection Ordinance
5. ^ Red Lists Hessen 1, p. 21 , Baden-Württemberg 2 p. 65 , Thuringia 1, p. 15 , Bavaria 1, p. 148 , Mecklenburg-Western Pomerania 2, decreasing, p. 16 , Saxony-Anhalt 2 p. 336
6. ↑ Carolus Linnaeus: Systema Naturae .... 1st volume, 10th edition, Stockholm 1758 p. 356: 352 No. 53 variabilis , p. 357: 353 No. 54 nobilis
7. ↑ ^{a b} Rösel von Rosenhof: Insect amusements 2nd volume. Plate III in an annotated Dutch edition of the Insect Amusements footnote by Kleemann
8. ↑ Carolus Linnaeus: Systema Naturae .... 1st volume, part 2, 12th edition, Stockholm 1767 p. 558, no. 79 variabilis , no. 81. nobilis
9. ↑ Carolus Linnaeus, Johann Friedrich Gmelin: Systema Naturae .... 1st volume, part 4 13th edition, Leipzig 1788 p. 1581, No. 79 variabilis p. 1582 No. 81 nobilis
10. ^ ^{A b} Johann Friedrich Wilhelm Herbst: Critical directory of my insect collection in the archive of insect history 4th issue, Zurich 1783 p. 17
11. ^ Johann Christian Fabricius: Systema entomologiae ... Flensburg, Leipzig 1775, p. 44 at BHL
12. ↑ ^{a b c} E. Mulsant, Eq. Rey: Histoire naturelle des coléoptères de France Paris 1871 [1]
13. ↑ The Bulletin of zoological nomenclature Volume 64 opinion 2186
14. ↑ The Bulletin of zoological nomenclature Volume 63 case 3349
15. ↑ ^{a b} p. 702 2nd subdiv. B. a
16. ↑ Sigmund Schenkling: Explanation of the scientific beetle names (genus)
17. ↑ Ludwig Redtenbacher: Fauna Austriaca - Die Käfer 1st volume, Vienna 1874 p.500
18. ↑ WF Erichson: Natural history of the insects of Germany 1st division Coleoptera Berlin 1845 Volume 3, Part 1 p. 583
19. ^ Hermann Burmeister: Handbuch der Entomologie 3rd volume Berlin 1842 Genus in the Google book search and type in the Google book search
20. ↑ Viktor Konschegg: "About the breeding of Gnorimus variabilis L. (Col.)" Wiener Entomologische Zeitung, 47th volume, 1st issue, March 30, 1930 PDF
21. ↑ ^{a b} Édouard Perris: Histoire des insectes du Pin maritime 1st volume, Käfer, Paris 1863 Description p. 140 , illustrations panel 4 Fig. 179 - 183
22. ↑ Distribution in southern Sweden, map p. 91
23. ↑ English page on the species
24. ↑ Distribution map of Europe ( memento of the original from September 25, 2015 in the Internet Archive ) 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.