''Dicopomorpha echmepterygis'' is the smallest known insect and a species of

parasitoid wasp Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causin ...

in the family

Mymaridae The Mymaridae, commonly known as fairyflies or fairy wasps, are a family of chalcidoid wasps found in temperate and tropical regions throughout the world. The family contains around 100 genera with 1400 species. Fairyflies are very tiny insects ...

, which exhibits strong

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

. The males are blind,

apterous Aptery is the anatomical condition of an animal completely lacking any kind of wings. An animal with this condition is said to be apterous. Most animal species belong to and are phylogenetic descendants of apterous taxa. These groups are said to ...

, and their body length is only 40% that of females. With a body length averaging 186 μm (for 8 specimens measured, which ranged from 139 to 240 μm), males of ''D. echmepterygis'' have the shortest body length of all known

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s (smaller than certain species of ''

Paramecium '' ''Paramecium'' ( , ; also spelled ''Paramoecium'') is a genus of eukaryotic, unicellular ciliates, commonly studied as a representative of the ciliate group. ''Paramecia'' are widespread in freshwater, brackish, and marine environments and a ...

'',

amoeba An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudop ...

, and shorter than certain bacteria, ''

Thiomargarita magnifica ''Thiomargarita magnifica'' is a species of sulfur-oxidizing gammaproteobacteria, found growing underwater on the detached leaves of red mangroves from the Guadeloupe archipelago in the Lesser Antilles. This filament-shaped bacteria is the large ...

'', all of which are single-celled organisms). The measured body length of a female was 550 μm. Dicopomorpha echmepterygis have relatively long legs and are dull grayish brown. They have small heads that lack compound eyes, with unsegmented antennae. Females, on the other hand, have entirely black bodies with dusky brown legs and antennae. The antennae are twice as long as they are wide compared to males. Compared to males, females have slender wings that are slightly narrowed through the middle. The eggs and larvae of this parasitoid are considerably smaller than the adult. This species, described from

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, is an

idiobiont In evolutionary ecology, a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasiti ...

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

of the eggs of a lepidopsocid

barklouse Psocoptera are a paraphyletic group of insects that are commonly known as booklice, barklice or barkflies. The name Psocoptera has been replaced with Psocodea in recent literature, with the inclusion of the former order Phthiraptera into Psocod ...

, '' Echmepteryx hageni''. Of five host eggs dissected, four contained one male and one female, the fifth one contained three males and one female. Adult males appear to mate with their sisters inside the host egg and die without ever leaving the egg. Similar life histories can be found with other species of Chalcidoidea, such as the trichogrammatid ''

Prestwichia aquatica ''Prestwichia aquatica'' is a species of Trichogrammatid wasp. References Trichogrammatidae Insects described in 1864 Taxa named by John Lubbock, 1st Baron Avebury {{chalcidoidea-stub ...

'', which also mates within the host egg, fig wasps in the family

Agaonidae The family Agaonidae is a group of pollinating and nonpollinating fig wasps. They spend their larval stage inside the fruits of figs. The pollinating wasps (Agaoninae, Kradibiinae, and Tetrapusiinae) are the mutualistic partners of the fig tree ...

, which exhibit similar sexual dimorphism and mate within the host fig, as well as in

mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...

s in the genus ''

Adactylidium ''Adactylidium'' is a genus of mites known for its unusual life cycle. An impregnated female mite feeds upon a single egg of a thrips Thrips (order Thysanoptera) are minute (mostly long or less), slender insects with fringed wings and u ...

'', which mate inside the body of their mother before they are born.

References

{{Taxonbar, from=Q138436 Mymaridae Insects described in 1997 https://animaldiversity.org/accounts/Dicopomorpha_echmepterygis/

See also

References