Metasoma

Last updated November 18, 2020

The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma.^[1] In insects, it contains most of the digestive tract, respiratory system, and circulatory system, and the apical segments are typically modified to form genitalia. In a few of the most primitive insects (the Archaeognatha), the metasomal segments bear small, articulated appendages called "styli", which are often considered to be vestigial. There are also pre-apical appendages in most insect orders, called cerci, which may be multi-segmented and almost resembling a posterior pair of antennae; these may be variously modified, or lost entirely. Otherwise, most adult insects lack appendages on the metasoma, though many larval insects (e.g., caterpillars) have some form of appendages, such as prolegs or, in aquatic insects, gills.

In apocritan Hymenoptera (wasps, bees and ants), the metasoma consists of the second abdominal segment (which typically forms a petiole) and those segments posterior to it, and is often called the gaster rather than referring to it as the "abdomen"; in these insects, the first abdominal segment is called the propodeum and is fused to the thorax. The metasoma is armoured with chitinous plates on the upper surface by the tergites and on the lower surface by the sternites.^[2]

In scorpions, the metasoma is the tail.^[3] In other chelicerates, such as spiders, the mesosoma is fused with the metasoma to form the opisthosoma.^[1]

Related Research Articles

Antennae, sometimes referred to as "feelers", are paired appendages used for sensing in arthropods.

The Apocrita are a suborder of insects in the order Hymenoptera. It includes wasps, bees, and ants, and consists of many families. It contains the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" (petiole) formed between the first two segments of the actual abdomen; the first abdominal segment is fused to the thorax, and is called the propodeum. Therefore, it is general practice, when discussing the body of an apocritan in a technical sense, to refer to the mesosoma and metasoma rather than the "thorax" and "abdomen", respectively. The evolution of a constricted waist was an important adaption for the parasitoid lifestyle of the ancestral apocritan, allowing more maneuverability of the female's ovipositor. The ovipositor either extends freely or is retracted, and may be developed into a stinger for both defense and paralyzing prey. Larvae are legless and blind, and either feed inside a host or in a nest cell provisioned by their mothers.

Stinger Sharp organ found in various animals capable of injecting venom

A stinger is a sharp organ found in various animals capable of injecting venom, usually by piercing the epidermis of another animal.

Gall wasps, also called gallflies, are a family (Cynipidae) in the wasp superfamily Cynipoidea within the suborder Apocrita of the order Hymenoptera. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this generally very small creature (1–8 mm) are known worldwide, with about 360 species of 36 different genera in Europe and some 800 species in North America.

The gaster is the bulbous posterior portion of the metasoma found in hymenopterans of the suborder Apocrita. This begins with abdominal segment III on most ants, but some make a constricted postpetiole out of segment III, in which case the gaster begins with abdominal segment IV.

In biology, a tagma is a specialized grouping of multiple segments or metameres into a coherently functional morphological unit. Familiar examples are the head, the thorax, and the abdomen of insects. The segments within a tagma may be either fused or so jointed as to be independently moveable.

The abdomen is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the trunk. The area occupied by the abdomen is called the abdominal cavity. In arthropods it is the posterior tagma of the body; it follows the thorax or cephalothorax.

This glossary of entomology describes terms used in the formal study of insect species by entomologists.

The propodeum or propodium is the first abdominal segment in Apocrita Hymenoptera. It is fused with the thorax to form the mesosoma. It is a single large sclerite, not subdivided, and bears a pair of spiracles. It is strongly constricted posteriorly to form the articulation of the petiole, and gives apocritans their distinctive shape. There may be a suture between the propodeum and the thorax, like in Symphyta or not, and the presence or absence of such suture can aid in identifying specimens.

The mesosoma is the middle part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the legs, and, in the case of winged insects, the wings.

In arthropods, the maxillae are paired structures present on the head as mouthparts in members of the clade Mandibulata, used for tasting and manipulating food. Embryologically, the maxillae are derived from the 4th and 5th segment of the head and the maxillary palps; segmented appendages extending from the base of the maxilla represent the former leg of those respective segments. In most cases, two pairs of maxillae are present and in different arthropod groups the two pairs of maxillae have been variously modified. In crustaceans, the first pair are called maxillulae.

Sphecomyrma is an extinct genus of ants which existed in the Cretaceous approximately 79 to 92 million years ago. The first specimens were collected in 1966, found embedded in amber which had been exposed in the cliffs of Cliffwood, New Jersey, by Edmund Frey and his wife. In 1967, zoologists E. O. Wilson, Frank Carpenter and William L. Brown, Jr. published a paper describing and naming Sphecomyrma freyi. They described an ant with a mosaic of features—a mix of characteristics from modern ants and aculeate wasps. It possessed a metapleural gland, a feature unique to ants. Furthermore, it was wingless and had a petiole which was ant-like in form. The mandibles were short and wasp-like with only two teeth, the gaster was constricted, and the middle and hind legs had double tibial spurs. The antennae were, in form, midway between the wasps and ants, having a short first segment but a long flexible funiculus. Two additional species, S. canadensis and S. mesaki, were described in 1985 and 2005, respectively.

The Sierolomorphidae are a family of about 10 known species of wasps, all in the genus Sierolomorpha, found in the Northern Hemisphere. They are rare and very little is known of their biology.

Insect morphology is the study and description of the 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 features separate insects from other arthropods: they have a body divided into three regions, have three pairs of legs, and mouthparts located outside of the head capsule. It is this position of the mouthparts which divides them from their closest relatives, the non-insect hexapods, which includes Protura, Diplura, and Collembola.

The study of the genitalia of Lepidoptera is important for Lepidoptera taxonomy in addition to development, anatomy and natural history. The genitalia are complex and provide the basis for species discrimination in most families and also in family identification. The genitalia are attached onto the tenth or most distal segment of the abdomen. Lepidoptera have some of the most complex genital structures in the insect groups with a wide variety of complex spines, setae, scales and tufts in males, claspers of different shapes and different modifications of the ductus bursae in females.

The thorax is the midsection (tagma) of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma or cephalothorax in other arthropods.

Kollasmosoma sentum is a parasitoid wasp in the family Braconidae, which lays its eggs inside adult ants. It was featured as one of "the top 10 new species of 2012" in a list compiled by Conservationists at the Arizona State University International Institute for Species Exploration.

Insects are among the most diverse groups of animals on the planet, including more than a million described species and representing more than half of all known living organisms. The number of extant species is estimated at between six and ten million, found in nearly all environments, although only a small number of species occur in the oceans. This large extant means that the dietary habits of taxa include a large variety of behaviors.

Most insects reproduce oviparously, i.e. by laying eggs. The eggs are produced by the female in a pair of ovaries. Sperm, produced by the male in one testis or more commonly two, is transmitted to the female during mating by means of external genitalia. The sperm is stored within the female in one or more spermathecae. At the time of fertilization, the eggs travel along oviducts to be fertilized by the sperm and are then expelled from the body ("laid"), in most cases via an ovipositor.

Zigrasimecia is an extinct genus of ants which existed in the Cretaceous period approximately 98 million years ago. The first specimens were collected from Burmese amber in Kachin State, 100 kilometres (62 mi) west of Myitkyina town in Myanmar. In 2013, palaeoentomologists Phillip Barden and David Grimaldi published a paper describing and naming Zigrasimecia tonsora. They described a dealate female with unusual features, notably the highly specialized mandibles. Other features include large ocelli, short scapes, 12 antennomeres, small eyes, and a clypeal margin that has a row of peg-like denticles. The genus Zigrasimecia was originally incertae sedis within Formicidae until a second species, Zigrasimecia ferox, was described in 2014, confirming its placement in the subfamily Sphecomyrminae.

References

1 2 D. R. Khanna & P. R. Yadav (2004). "Segmentation in arthropods". Biology of Arthropoda. Discovery Publishing House. pp. 316–394. ISBN 978-81-7141-897-8.
↑ Donald L. J. Quicke (2009). "Hymenoptera (ants, bees, wasps)". In Vincent H. Resh & Ring T. Cardé (ed.). Encyclopedia of Insects (2nd ed.). Academic Press. pp. 473–484. ISBN 978-0-12-374144-8.
↑ Stanley C. Williams (2009). "Scorpions". In Vincent H. Resh & Ring T. Cardé (ed.). Encyclopedia of Insects (2nd ed.). Academic Press. pp. 904–909. ISBN 978-0-12-374144-8.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[Khanna-1] 1 2 D. R. Khanna & P. R. Yadav (2004). "Segmentation in arthropods". Biology of Arthropoda. Discovery Publishing House. pp. 316–394. ISBN 978-81-7141-897-8.

[2] Donald L. J. Quicke (2009). "Hymenoptera (ants, bees, wasps)". In Vincent H. Resh & Ring T. Cardé (ed.). Encyclopedia of Insects (2nd ed.). Academic Press. pp. 473–484. ISBN 978-0-12-374144-8.

[3] Stanley C. Williams (2009). "Scorpions". In Vincent H. Resh & Ring T. Cardé (ed.). Encyclopedia of Insects (2nd ed.). Academic Press. pp. 904–909. ISBN 978-0-12-374144-8.