Archedictyon (from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''Arche'' meaning first, original, ancient, primitive, or most basic and ''dictyo-'' meaning net or netlike, plural "archedictya") is a name given to a

hypothetical A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess or tho ...

scheme of

wing venation Insect wings are adult outgrowths of the insect exoskeleton that enable insect flight, insects to fly. They are found on the second and third Thorax (insect anatomy), thoracic segments (the mesothorax and metathorax), and the two pairs are often ...

proposed for the

common ancestor Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonl ...

of all winged insects.

Description

The nature of the archedictyon is an important consideration in the

taxonomic classification In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon), and these groups are given ...

of the large, primitive

Palaeozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of ...

insects known as

Palaeodictyoptera The Palaeodictyoptera are an extinct order of medium-sized to very large, primitive Palaeozoic paleopterous insects. They are informative about the evolution of wings in insects. Overview They were characterized by beak-like mouthparts, used ...

and was used by

Adolphe-Théodore Brongniart Adolphe-Théodore Brongniart () FRS FRSE FGS (14 January 1801 – 18 February 1876) was a French botanist. He was the son of the geologist Alexandre Brongniart and grandson of the architect, Alexandre-Théodore Brongniart. Brongniart's pioneerin ...

for this purpose as early as 1854. A

National Museum of Natural History The National Museum of Natural History (NMNH) is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. With 4.4 ...

database In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and a ...

for the study of

ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...

s, bees and

termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...

s describes the archedictyon as:

...the primitive original vein network characterizing the wings of many of the most ancient insect fossils (T-B, after Needham; Mackerras, in
CSIRO The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency that is responsible for scientific research and its commercial and industrial applications. CSIRO works with leading organisations arou ...
); in Mastotermitidae and
Hodotermitidae The Hodotermitidae (from Greek ὁδός (hodós), travelling; Latin '' termes'', woodworm) are a basal Old World family of termites known as the harvester termites. They are distinguished by the serrated inner edge of their mandibles, and th ...
(
Isoptera Termites are a group of detritophagous eusocial cockroaches which consume a variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the soft-bo ...
), the complex network or
reticulum Reticulum is a small, faint constellation in the southern sky. Its name is Latin for a small net, or reticle—a net of crosshairs at the focus of a telescope eyepiece that is used to measure star positions. The constellation is best viewed b ...
of irregular veinlets between the veins in the apical 3 quarters of both wings, including the anal lobe (Emerson).

According to a 1999

scientific paper Scientific literature encompasses a vast body of academic papers that spans various disciplines within the natural and social sciences. It primarily consists of academic papers that present original empirical research and theoretical ...

about the evolution of flight in Palaeozoic Palaeoptera, although the archedictyon of some Palaeodictyoptera have long been believed to be generalized

plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, an ...

reticulation from which true cross veins developed through

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

, these may actually be an adaptive feature.

Structure

The archedictyon is believed to have contained between six and eight longitudinal

veins Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal c ...

, but current understanding of the design is based on a combination of

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

and speculation. The " Comstock-Needham system" designed by

entomologists Entomology (from Ancient Greek ἔντομον (''éntomon''), meaning "insect", and -logy from λόγος (''lógos''), meaning "study") is the branch of zoology that focuses on insects. Those who study entomology are known as entomologists. In ...

John Henry Comstock John Henry Comstock (February 24, 1849 – March 20, 1931) was an eminent researcher in entomology and arachnology and a leading educator. His work provided the basis for classification of butterflies, moths, and scale insects. Career Comstock w ...

and George Needham describes these veins and their branches: :*Costa (C): the leading edge of the wing :*Subcosta (Sc): the second longitudinal vein (behind the costa), typically unbranched :*Radius (R): the third longitudinal vein, one to five branches reach the wing margin :*Media (M): the fourth longitudinal vein, one to four branches reach the wing margin :*Cubitus (Cu): fifth longitudinal vein, one to three branches reach the wing margin :*Anal veins (A1, A2, A3): the unbranched veins behind the cubitus
North Carolina State University Crossveins are named based on their relative position to the more prominent longitudinal veins: :*C-SC crossveins run between the costa and subcosta :*R crossveins run between adjacent branches of the radius :*R-M crossveins run between the radius and media :*M-CU crossveins run between the media and cubitus

Extant species

The hypothetical primitive wing venation pattern is often used as a basis for describing the pattern in modern insects. In Extant taxon, extant insects, the term implies a retention of primitive characteristics but not necessarily a simplicity of design in comparison to the veinous network of other modern insect wings. Contemporary insects with wings to which the term ''archedictyon'' has been applied include the termite ''

Mastotermes darwiniensis ''Mastotermes darwiniensis'', common names giant northern termite and Darwin termite, is a termite species found only in northern Australia. It is the most primitive extant termite species. Contrary to common belief, this species does not form m ...

'' from

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

(''illustration'') and the

praying mantis Mantises are an order (Mantodea) of insects that contains over 2,400 species in about 460 genera in 33 families. The largest family is the Mantidae ("mantids"). Mantises are distributed worldwide in temperate ...

'' Orthodera novaezealandiae'' from

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. The term is also used in the discussion of phasmids and in such case refers to:

A network of non-directional veins in the costal region of the wing or in the
elytron An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes ...
. It is these veins which make the elytron and costal region of the
hindwing Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments (the mesothorax and metathorax), and the two pairs are often referred to as the forewings and hindw ...
thicker and stiffer than the anal region of the hindwing. Glossary of terms used to describe phasmids

Bibliography

"An enigmatic Palaeozoic stem-group: Paoliida: designation of new taxa from the Upper Carboniferous of the Czech Republic"
(pdf file)

References

{{reflist Insect morphology

Description

Structure

Extant species

See also

Bibliography

References