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The mesothorax is the middle of the three segments of the
The mesothorax is the middle of the three segments of the thorax
The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen.
In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...
of hexapods, and bears the second pair of legs. Its principal sclerites (exoskeletal plates) are the mesonotum (dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
The fus ...
), the mesosternum ( ventral), and the mesopleuron (lateral
Lateral is a geometric term of location which may also refer to:
Biology and healthcare
* Lateral (anatomy), a term of location meaning "towards the side"
* Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx
* Lateral release ( ...
) on each side. The mesothorax is the segment that bears the forewings in all winged insects, though sometimes these may be reduced or modified, as in beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s ( Coleoptera) or Dermaptera, in which they are sclerotized to form the elytra ("wing covers"), and the Strepsiptera, in which they are reduced to form halteres that attach to the mesonotum. All adult insects possess legs on the mesothorax. In some groups of insects, the mesonotum is hypertrophied, such as in Diptera, Hymenoptera
Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic.
Females typi ...
, and Lepidoptera
Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...
), in which the anterior portion of the mesonotum (called the mesoscutum, or simply "scutum") forms most of the dorsal surface of the thorax. In these orders, there is also typically a small sclerite attached to the mesonotum that covers the wing base, called the tegula. In one group of insects, the Hemiptera
Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...
, the dorsal surface of the thorax is typically formed primarily of the prothorax, but also in part by the enlarged posterior portion of the mesonotum, called the scutellum; in the Coleoptera, the scutellum may or may not be visible, usually as a small triangular plate between the elytral bases, thus similar in position to the Hemiptera
Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...
n scutellum. In Diptera and Hymenoptera
Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic.
Females typi ...
the mesothoracic scutellum is also distinct, but much smaller than the mesoscutum.
See also
*Glossary of entomology terms
This glossary of entomology describes terms used in the formal study of insect species by entomology, entomologists.
A–C
A synthetic chlorinated hydrocarbon insecticide, toxic to vertebr ...
*Insect morphology
Insect morphology is the study and description of the morphology (biology), physical form of insects. The terminology used to describe insects is similar to that used for other arthropods due to their shared evolutionary history. Three physical f ...
* Metathorax
* Prothorax
* Thorax (arthropod anatomy)
References
Insect anatomy {{insect-anatomy-stub