The Dixidae (meniscus

midge A midge is any small fly, including species in several family (biology), families of non-mosquito nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid ...

s) are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

nematocera The Nematocera (the name meaning "thread-horns") are a suborder of elongated fly, flies with thin, segmented antenna (biology), antennae and mostly aquatic larvae. This group is paraphyletic and contains all flies except for species from suborder ...

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

(Diptera). The

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e live in unpolluted, standing

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salt (chemistry), salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include ...

s, just beneath the surface film, usually amongst marginal aquatic vegetation. They are found in all continents except Antarctica.

Description

Dixidae are small (body length not more than 5.0 mm) slender gnats with thin legs. Adults are black to yellowish-brown. The head is relatively broad. The antennae are thin and the flagellum has 14 segments. The proboscis is short and thick and the palpi are five-segmented. The thorax is slightly convex. The wing veins are without scales (with scales in the closely related family

Culicidae Mosquitoes, the Culicidae, are a Family (biology), family of small Diptera, flies consisting of 3,600 species. The word ''mosquito'' (formed by ''Musca (fly), mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mos ...

). The subcosta is fused with the costa at the level of the base of Rs or slightly proximal to this. The wing venation exhibits radial, medial, and cubital forks (R 4 branched, M 2 branched, Cu 2 branched). R 2+ 3 is strongly arched, the r–m crossvein is distinct, and the discal cell is absent. The anal vein of the wing is long. The genitalia of the male is inverted at 180° by torsion of segments 5–8.

Evolutionary history

The oldest known fossils of the group come from the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

of Asia, assigned to the extinct genera '' Syndixa'' and ''

Eucorethrina ''Eucorethrina'' is a genus of flies belonging to the family Chaoboridae Chaoboridae, commonly known as phantom midges or glassworms, is a family of fairly common midges with a cosmopolitan distribution. They are closely related to the Coreth ...

,'' members of modern genera are not known until the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

References

External links

Delta Int Key
family description and image
BugGuideWing venationEOL
images
Diptera.info
images * Dixiidae in Italian Nematocera families {{Culicoidea-stub

Description

Evolutionary history

References

Further reading

External links