Hypopygium

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Hypopygium of a snake

Hypopygium is the name given to the sternum , i.e. the abdominal part of the mostly modified last abdominal segment in many groups of insects . Its morphology plays an essential role in the systematic classification of species. In many cases, especially in the Diptera (Diptera), is meant the entire last abdominal segment, which the copulatory organs contains. It is then also called the Terminalium .

Two-winged

In the two-winged animals, the hypopygium is the ninth abdominal segment and has some special features. Twisting ( torsion ) of the hypopygium can occur during pupal development or in the adult stage . During the pupal stage a rotation of 360 ° is possible, in the case of adults , the rotation of 180 ° takes place through muscle action. These rotations have led to different naming of homologous formations of the hypopygium in different species of the two-winged species.

Hymenoptera

Also in the hymenoptera the hypopygium shows different special formations, which are used especially in the ants to differentiate the subfamilies. The ants' original structure comprises eleven segments. However, only seven segments are visible in the females of most species, and nine in the males. The sternum of the last visible segment is always referred to as the hypopygium. In some genera of ants it contains the acidopore , through which formic acid is expelled from certain glands. However, this formation of the hypopygium only occurs in the females of the ant subfamily of scale ants (Formicinae). In the other subfamilies, the hypopygium is a simple, trapezoidal plate that carries some rearward-facing sensory hairs. These serve as tactile receptors that indicate the location of the abdomen. The sheath that carries the sting in some species of predatory ants, such as the genus Leptogenys, is constructed similarly to the acidopore . The genera of the subfamily of gland ants (Dolichoderinae) only have a slit-shaped cloacal opening between the telson and hypopygium instead of a spike .

Individual evidence

  1. ^ Lajos Zombori, Henrik Steinmann: Dictionary of Insect Morphology. Volume 34 of: Maximilian Fischer (Ed.): Handbuch der Zoologie. Volume 4. Arthropoda: Insecta. Walter de Gruyter, 1998, p. 88 ISBN 3-1101-4898-6
  2. ↑ E. Martine: An interesting variant on the hypopygium of a culicide. Entomologische Mitteilungen, 17, 2, pp. 138-140, 1928
  3. ↑ Akey CF Hung and William L. Brown, Jr .: Structure of Gastric Apex as a Subfamily Character of the Formicinae (Hymenoptera: Formicidae). Journal of the New York Entomological Society, 74, 4, pp. 198-200, December 1966
  4. ^ Roberto Keller: Homology Weekly: Hypopygium. Archetype, December 12, 2008

literature

  • FW Edwards: The Nomenclature of the Parts of the Male Hypopygium of Diptera Nematocera, with Special Reference to Mosquitos. The Annals of Tropical Medicine and Parasitology, 14, 1, pp. 23–40, 1920 PDF (English)
  • Theodor Schräder: The Hypopygium “circumversum” of Calliphora erythrocephala. A contribution to the knowledge of the copulatory apparatus of the Diptera. Zoomorphology, 8, 1-2, pp. 1-44, 1927 doi : 10.1007 / BF00464880
  • Robert E. Snodgrass: The Hypopygium of the Dolichopodidae. Proceedings of the California Academy of Sciences, Third Series Zoology, 3, 10, 1904

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