Cheironitis furcifer

Cheironitis furcifer
Male of Cheironitis furcifer
Systematics
Order : Beetle (Coleoptera) Subordination : Polyphaga Family : Scarab beetle (Scarabaeidae) Subfamily : Scarabaeinae Genre : Cheironitis Type : Cheironitis furcifer
Scientific name
Cheironitis furcifer
Rossi , 1792

Fig. 1: Females, top view	Fig. 2: Male, underside
Fig. 3: Male, portrait	Fig. 4: Male, side view
Fig. 5: female, head	Fig. 6: Male, head
Fig. 7: Male breastplate	Fig. 8: Front leg, above ♂ below ♀

Cheironitis furcifer (also cripple pill beetle ) is a beetle from the family of scarab beetles (Scarabaeidae) and the subfamily Scarabaeinae . Males and females show significant differences in physique and were therefore originally described as two different species. The male is characterized by monstrous extensions of the exoskeleton , which allow a better grip on the female during copulation.

The medium-sized beetles that are widespread in southern Europe are faecal eaters ( coprophagous ).

Comments on the name and system

A male of the species was first described by the Italian Rossi in 1792 under the name Scarabaeus furcifer in the 1st mantissa of his fauna Etrusca . The brief introductory characterization of the species ends with the words pectore bifurcato ( Latin with forked breast), in the detailed description Rossi explains : Pectus spinis duabus validis instar furcae armatum (Latin: the breast is reinforced with two strong spikes similar to a fork) . This explains the species name furcifer (from Latin furca, fork and fero, I bring, furcifer = carrying a fork), which Rossi gives of the newly described species and which refers to the fact that the male follows one behind the front hips on the underside of the body bears fork with two prongs open at the bottom (Fig. 2).

Rossi describes Scarabaeus furcifer under number 7. In the same publication directly above Rossi describes under number 6 a beetle with the name Scarabaeus irrotatus . He himself suspects that furcifer and irrotatus could be males and females of the same species and, unlike furcifer , does not give irrotatus an asterisk to mark a newly described species. Charpentier suggests the name furcifer for the species and puts it in the genus Onitis . Today Cheironitis irrotatus is not included in Cheironitis furcifer .

In the genus Scarabaeus (already ancient Greek σκάραβος skárabos is a collective term for the majority of beetles) Linnaeus and his immediate successors put all beetles whose antennae are club-shaped towards the end with lamellas and whose front rails are often toothed ( Antennae clavatae capitualo fissili, Tibiae capitualo fissili saepius dentatae ). With the multiple splitting of Scarabaeus the kind furcifer is then placed among the dung beetles and in the genus Onitis . Lansberge separated the new genus Cheironitis from Onitis in his monograph des Onites (Monograph of Onitini ) in 1875 . Reitter and the authors standing in his tradition use the name in the spelling of chironitis . According to the Latin definition of the new genus, Lansberge begins the detailed French description with the comment: The presence of tarsi on the forelegs of the females separate this [species] from all other onitis . This explains the generic name Cheironitis from the generic name Onitis and old Gr . χείρ chēīr hand as onitis , in which (in females) the foot of the foreleg (the hand) is not missing.

The genus Cheironitis includes thirteen Palearctic species, ten African species; one species is an oriental element of fauna. There are six or seven species in Europe, depending on whether Cheironitis irrotatus is considered a subspecies of Cheironitis ungaricus or as an independent species. The generic name was mostly written as " Chironitis " until the 1970s .

Characteristics of the beetle

The length of the beetle varies from thirteen to over twenty-two millimeters, with the males usually being larger than the females. The body is glossy to matt black, the wing covers matt. The beetle is about twice as long as it is wide, relatively flat and not very rounded.

The head (Fig. 5 and 6) is roughly double trapezoidal when viewed from above. It is absent- mindedly dotted and somewhat raised and cut out at the front edge. He has three cross bars. The first is very short and is located on the head shield ( clypeus ). The second is located in front of the front edge of the eyes and merges laterally into the seam that separates the head shield and cheeks from one another. In females it is interrupted in the middle by a hump (Fig. 5). The rear cross bar is wider than the middle one. The first six segments of the nine-segment antennae are bare, the last three are nested and form a pubescent, hairy, roughly spherical club. The lip buttons are tripartite, the second link is significantly longer than the first, both are very hairy. The third link is bald and small, but clearly visible.

The pronotum in the male (Fig. 7) is significantly longer than it is wide, in the female it is wider than it is long (Fig. 1). In the female there is a transverse bulge in the middle above the front edge, which is missing in the male. In both sexes, the pronotum is rounded at the sides and back. It is absent-mindedly dotted and bordered all around. The edge is notched on the sides. The pronotum bears four pit-shaped impressions. One larger and one flatter one is on the side of the pronotum, two more prominent ones lie closer to each other on the right and left in front of the scutellum . The label is clearly visible and bluntly pointed towards the rear (Fig. 7).

The elytra are roughly rectangular when viewed from above, together a little less wide than the pronotum. They have eight fine point stripes. Next to the seventh they are raised like a keel, as if folded, next to them the outside folds down vertically (Fig. 4). The wing covers also drop steeply towards the rear. The elytra are usually black, but they can also be reddish.

The sex differences are most evident on the front legs (Fig. 8). The tarsi are missing in the male (Fig. 8 above) . The rails are long, slender, and curved outwards. The spike is missing at the front end. On the outside there is a larger tooth in the middle, in front of it one or two smaller ones, on the inside they are irregularly serrated, on the underside they have a row of bristles. At the end of the fore thigh there is a very strong tooth directed close to the front, in the middle a noticeably long and flat lamellar extension that is directed forward and slightly downward. It is staggered about twice on each long side. The front hips are very close to each other. At the point where they reach the level of the front chest, behind the front hips, sits the eponymous fork-shaped outgrowth with the two pointed long thorns (Fig. 2 and 4). These point outwards and downwards and form an angle of just over 90 ° to one another.

In the female, the front legs correspond more to the basic type of a grave bone (Fig. 8 below). They have five-part, rather poorly developed tarsi. A strong mandrel sits on the inside at the front end of the rail. The splints are only about half as long as those of the males and have three to four flattened strong teeth on the outside. The fore legs are without protrusions and the fork is absent at the base of the front hips.

The central splints have two terminal spines, the parallel central hips are widely separated from one another by the metasternum. The back rails are short and wide with an end pin on the inside. The middle and hind tarsi are five-limbed, the hind tarsi are long haired with black bristles.

Notes on the explanation of sexual dimorphism

Darwin makes two comments on Cheironites furcifer in his book The Descent of Man . On the one hand, he suspects that, in analogy to other insects, the fork and the appendages on the fore legs have developed in the male so that the male can better cling to the female during mating. Darwin explains two special forms of the female as rudiments . He sees the hump on the forehead ridge and the bulge on the front edge of the breast shield as a remnant of a horn on the head and a distinct protrusion of the pronotum, which is still present in related species and has completely receded in the male.

biology

The breeding behavior of the species is classified as primitive compared to other beetle species, which also secure manure supplies as a food source for the larvae. The beetles dig a passage straight down under the dung heap. Various diverging galleries are created at the end of this. The ends of these branches are filled with manure from the heap, creating sausage-shaped manure structures. The female lays an egg in each of these dung sausages. Males and females work independently, but cooperatively. The female digs the galleries, the male loosens the manure from the excrement heap and transports it to the main course. The female fills the ends of the galleries.

The larvae have the shape of grubs and are colored like them. There are three larval stages.

Occurrence

The species is distributed around the Mediterranean (circummediterranean). Widespread from North Africa (southern Morocco to Egypt), over Syria, the island of Lesbos, Thrace , Greece and the western Balkans, Italy including the islands of Sicily and Sardinia, the Balearic Islands to western Spain.

Individuals of eastern populations often have brown elytra.

Individual evidence

1. ↑ Jakob Sturm: Catalog of the kaefer collection . Printed at the author's expense, 1843 ( google.de [accessed February 18, 2019]).
2. ↑ ^{a b} Cheironitis furcifer in Fauna Europaea. Retrieved April 7, 2013
3. ↑ ^{a b c} P. Rossi, J.Chr.L. Hellwig: Mantissae priore parte adiecta zu Fauna Etrusca Helmstedt 1795 First description of the species as No. 7 on page 340
4. ↑ Toussaint de Charpentier: Horae entomologicae, adjectis tabulis novem coloratis Wratislavia 1825 p. 204
5. ↑ Sigmund Schenkling: Nomenclator coleopterologus 2nd edition Jena 1922 Explanation of the scientific beetle names (genus) in short form
6. ↑ C.Linnaeus: Systema Naturae per Regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata Stockholm 1758 p. 345, no.170
7. ↑ ^{a b c d} G. van Lansberge: Monograph of the Onitides Annales de la Société entomologique de Belgique, Vol. 18, 1875 p. 19. April 11, 1814 Definition of the new genus p. 19, Species description p. 23
8. ↑ Edmund Reitter (Ed.): Catalogus Coelopterorum Europae, ... Editio secunda, Berlin, Paskau, Caen 1906
9. ↑ Heinz Freude , Karl Wilhelm Harde , Gustav Adolf Lohse (ed.): Die Käfer Mitteleuropas . tape  8 . Teredilia Heteromera Lamellicornia . Elsevier, Spektrum, Akademischer Verlag, Munich 1969, ISBN 3-8274-0682-X .
10. ^ Cheironitis in Fauna Europaea. Retrieved April 7, 2013
11. ↑ Species of the genus Cheironitis at BioLib
12. ↑ ^{a b c d} FMPiera, JILColón: Fauna Iberica, Superfamilia Scarabaeoidea CSIC-Depto. de Publicaciones 2000
13. ↑ Tristão Branco & Stefano Ziani (2005): Cheironitis Lansberge, 1875, it's correct spelling and validity (Coleoptera, Scarabaeidae). Boletín Sociedad Entomológica Aragonesa 37: 267-272.
14. ^ Encyclopédie méthodique. Histoire naturelle. Insectes Paris 1789-1825, p. 490, no. 4
15. ^ Charles Darwin: Decent of man, Chapter X: Secondary sexual characters of insects as html
16. ^ F. Martin-Piera (1987): Review of the Genus Chironitis Lansberge, 1875. I: Taxonomy, Phylogeny and Zoogeography of the Palearctic Species (Col. Scarabaeoidea, Onitini). Entomological work from the Museum G. Frey Tutzing 35/36: 203–243.

Web links

Commons : Cheironitis furcifer  - album with pictures, videos and audio files