Comstock–Needham system
Encyclopedia
The Comstock–Needham system is a naming system for insect
wing
veins, devised by John Comstock
and George Needham
in 1898. It was an important step in showing the homology
of all insect wings. This system was based on Needham's pretracheation theory that was later discredited by Frederic Charles Fraser
in 1938.
The Comstock and Needham system attributes different names to the veins on an insect's wing. From the anterior (leading) edge of the wing towards the posterior (rear), the major longitudinal
veins are named :costa C, meaning rib'subcosta Sc, meaning below the rib'radius R, in analogy with a bone in the forearm, the radius
media M, meaning middle'cubitus Cu, meaning elbow'anal veins A, in reference to its posterior location
Apart from the costal and the anal veins, each vein can be branched, in which case the branches are numbered from anterior to posterior. For example, the two branches of the subcostal vein will be called Sc1 and Sc2.
The radius typically branches once near the base, producing anteriorly the R1 and posteriorly the radial sector Rs. The radial sector may fork twice.
The media may also fork twice, therefore having four branches reaching the wing margin.
According to the Comstock–Needham system, the cubitus forks once, producing the cubital veins Cu1 and Cu2.
According to some other authorities, Cu1 may fork again, producing the Cu1a and Cu1b.
As there are several anal veins, they are called A1, A2, and so on. They are usually unforked.
In the case where two cells are separated by a crossvein but have the same anterior longitudinal vein, they should have the same name. To avoid this, they are attributed a number. For example, the R1 cell is divided in two by the radial cross vein : the basal cell is termed "first R1", and the distal cell "second R1".
If a cell is bordered anteriorly by a forking vein, such as R2 and R3, the cell is named after the distal vein, in this case R3.
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
wing
Insect wing
Insects are the only group of invertebrates known to have evolved flight. Insects possess some remarkable flight characteristics and abilities, still far superior to attempts by humans to replicate their capabilities. Even our understanding of the aerodynamics of flexible, flapping wings and how...
veins, devised by John Comstock
John Henry Comstock
John Henry Comstock 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.-Early life and education:...
and George Needham
James George Needham
James George Needham was an American entomologistAfter studying with John Henry Comstock at Cornell University he taught biology at Lake Forest University .In 1908 returned to Cornell as assistant professor of limnology.When Comstock retired in 1914, Needham became head of the Department of...
in 1898. It was an important step in showing the homology
Homology (biology)
Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...
of all insect wings. This system was based on Needham's pretracheation theory that was later discredited by Frederic Charles Fraser
Frederic Charles Fraser
Frederic Charles Fraser was an English entomologist who specialised in Odonata. Following army service in India as a surgeon with the rank of Lieutenant Colonel, Fraser devoted himself entirely to dragonflies, mostly in the British Museum where his collection is maintained. Fraser's...
in 1938.
Longitudinal veins
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
veins are named :costa C, meaning rib'subcosta Sc, meaning below the rib'radius R, in analogy with a bone in the forearm, the radius
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...
media M, meaning middle'cubitus Cu, meaning elbow'anal veins A, in reference to its posterior location
Apart from the costal and the anal veins, each vein can be branched, in which case the branches are numbered from anterior to posterior. For example, the two branches of the subcostal vein will be called Sc1 and Sc2.
The radius typically branches once near the base, producing anteriorly the R1 and posteriorly the radial sector Rs. The radial sector may fork twice.
The media may also fork twice, therefore having four branches reaching the wing margin.
According to the Comstock–Needham system, the cubitus forks once, producing the cubital veins Cu1 and Cu2.
According to some other authorities, Cu1 may fork again, producing the Cu1a and Cu1b.
As there are several anal veins, they are called A1, A2, and so on. They are usually unforked.
Crossveins
Crossveins link the longitudinal veins, and are named accordingly (for example, the medio-cubital crossvein is termed m-cu). Some crossveins have their own name, like the humeral crossvein h and the sectoral crossvein s.Cell terminology
The cells are named after the vein on the anterior side; for instance, the cell between Sc2 and R1 is called Sc2.In the case where two cells are separated by a crossvein but have the same anterior longitudinal vein, they should have the same name. To avoid this, they are attributed a number. For example, the R1 cell is divided in two by the radial cross vein : the basal cell is termed "first R1", and the distal cell "second R1".
If a cell is bordered anteriorly by a forking vein, such as R2 and R3, the cell is named after the distal vein, in this case R3.