Astigmatina is a clade of

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 superorder

Acariformes The Acariformes, also known as the Actinotrichida, are the most diverse of the two superorders of mites. Over 32,000 described species are found in 351 families, with an estimated total of 440,000 to 929,000 species, including undescribed species ...

Astigmata Astigmatina is a clade of mites in the superorder Acariformes. Astigmata has been ranked as an order or suborder in the past, but was lowered to the unranked clade Astigmatina of the clade Desmonomatides (synonym Desmonomata) in the order Sarcopt ...

has been ranked as an order or suborder in the past, but was lowered to the unranked clade Astigmatina of the clade Desmonomatides (synonym Desmonomata) in the order

Sarcoptiformes The Sarcoptiformes are an order of Acari comprising over 15,000 described species in around 230 families. Previously it was divided into two suborders, Oribatida and Astigmatina, but Oribatida has been promoted to an order, and Astigmatina is n ...

. Astigmatina is now made up of the two groups Acaridia and

Psoroptidia Psoroptidia is a parvorder of the Acari (mite) group Astigma (or Astigmatina). It comprises around 40 families, and apparently originated as parasites of birds, before a secondary radiation saw some taxa become parasites of mammals. Because of t ...

, which have been suborders of the order Astigmata in the past. Astigmatina contains about 10 superfamilies and 76 families under Acaridia and Psoroptidia. Astigmatina belongs to the

, which contains the "biting"

. Many

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

are

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s of

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

s. Most notorious among these are the

, which contain such notable

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

feather mite Feather mites are the members of diverse mite superfamilies: * superorder Acariformes ** Psoroptidia *** Analgoidea *** Freyanoidea *** Pterolichoidea * superorder Parasitiformes ** Dermanyssoidea They are ectoparasites on bird Bird ...

s and ''

Sarcoptes scabiei ''Sarcoptes scabiei'' or the itch mite is a parasitic mite that burrows into skin and causes scabies. The mite is found in all parts of the world. Humans are not the only mammals that can become infected. Other mammals, such as wild and domesti ...

''.

Description

Astigmatan mites are usually soft-bodied and white to brownish in colour (rarely tan and well-sclerotised), and range from 0.15 to 2.00 mm in length. They lack stigmatal openings (thus the name of the clade), peritremes or prodorsal

sensilla A sensillum (plural ''sensilla'') is an arthropod sensory organ protruding from the cuticle of exoskeleton, or sometimes lying within or beneath it. Sensilla appear as small hairs or pegs over an individual's body. Inside each sensillum there are ...

. The

gnathosoma The gnathosoma (from Greek , ' = "jaw" and , ' = "body") is the part of the body of the Acari (mites and ticks) comprising the mouth and feeding parts. These are the hypostome, the chelicerae and the pedipalps. It is also called the capitulum (howe ...

(mouthparts) is usually exposed. They have a pair of

chelicerae The chelicerae () are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated fangs, or similarly ...

that are 2-segmented and usually chelate-dentate in shape (whip-like in Histiostomatidae).

Opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma (cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects to a ...

l glands are present and usually well-developed. Some features vary depending on the life stage. Larvae have six legs (hexapod) whereas nymphs and adults have eight legs (octopod). The genital opening has one pair of genital papillae in the protonymph (first nymphal stage), but two pairs in the tritonymph (last nymphal stage) and adult. Some astigmatans have a deutonymph stage which looks very different from other stages (heteromorphic). This is usually adapted for

phoresy Phoresis or phoresy is a non-permanent, Commensalism, commensalistic interaction in which one organism (a phoront or phoretic) attaches itself to another (the host) solely for the purpose of travel. Phoresis has been observed directly in Acari ...

(attachment to a larger animal for transport), being well-sclerotised (to resist

desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

), with a reduced gnathosoma and a solid, non-functional foregut (as deutonymphs generally do not feed) and usually a posteroventral attachment organ. Some lineages have two possible types of heteromorphic deutonymph, with the other being sac-like and immobile (immobile heteromorphic deutonymph). The purpose of this deutonymph type is to survive environmental stresses for long periods of time. Males have an

aedeagus An aedeagus (plural aedeagi) is a reproductive organ of male arthropods through which they secrete sperm from the testes during copulation with a female. It can be thought of as the insect equivalent of a mammal's penis, though the comparison ...

in a usually postcoxal position. Females have a secondary

sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...

-receiving structure with a bursa copulatrix.

Ecology

Unlike their oribatid ancestors, which are mostly restricted to soil, the Astigmatina show a wide range of ecological strategies. The Histiostomatoidea live in various wet substrates such as decaying plant tissue, dung, mud and tree holes, and feed on organic material. The Glycyphagoidea live in mammal nests, human houses and stored foods. The Pyroglyphoidea live in houses as

house dust mite House dust mites (HDM, or simply dust mites) are various species of acariform mites belonging to the family Pyroglyphidae that are found in association with dust in dwellings. They are known for causing allergies. Biology Species The current ...

s. Many Acaroidea live in stored foods, but the superfamily also includes plant pests and inhabitants of vertebrate or insect nests. The majority of Hemisarcoptoidea are kleptoparasites. The Canestrinoidea are parasites feeding on exudates of beetles. The also-parasitic Sarcoptoidea live in mammal fur and skin. Several superfamilies are exclusively associated with birds ( Pterolichoidea, Freyanoidea and

Analgoidea The Analgoidea are a superfamily of the Acarina (mite) order Sarcoptiformes. They contain many feather mites, being ectoparasites of birds and occasionally mammals. Families * Alloptidae Gaud, 1957 * Analgidae Trouessart & Mégnin, 1884 * A ...

) or bird nests ( Hypoderatoidea). Among the mites occurring in soil, Astigmatina is the least common group, though they may be common in some habitats. Their populations in agricultural soils increase after harvesting or the application of rich manures. Most soil-dwelling Astigmatina are microbe feeders, though the species with chelate chelicerae can chew on vegetable material,

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

and

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

. Several astigmatan families are obligate associates of

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

s, which feed within bee nests. The genus '' Chaetodactylus'' can form both phoretic deutonymphs (to disperse to new nests on adult bees) and immobile deutonymphs (to survive in old nests so they can infest bees that reuse nests).

Economic importance

Astigmatina in homes damage stored products, disperse microbial propagules and contribute to allergic reactions. The parasitic species cause diseases such as

scabies Scabies (; also sometimes known as the seven-year itch) is a contagious skin infestation by the mite ''Sarcoptes scabiei''. The most common symptoms are severe itchiness and a pimple-like rash. Occasionally, tiny burrows may appear on the skin ...

and

mange Mange is a type of skin disease caused by parasitic mites. Because various species of mites also infect plants, birds and reptiles, the term "mange", or colloquially "the mange", suggesting poor condition of the skin and fur due to the infection ...

. A few acarid species are minor pests of seedling crops. There are also beneficial species of Astigmatina. '' Hemisarcoptes'' ( Hemisarcoptidae) are parasites of armoured scale insects, which are plant pests.

Taxonomy

Astigmatina contains about 11 superfamilies with thousands of genera, as follows: ; Acaridia (> 400 genera, > 1300 species) * Schizoglyphoidea (2 genera, 2 species) ** Schizoglyphidae * Histiostomatoidea (c. 60 genera, > 200 species) **

Histiostomatidae Histiostomatidae is a family of mites in the clade Astigmata. Description These mites are characterized by a very small size (about 600–900 µm in length) and a close association to arthropods, mainly insects. A morphologically special ...

** Guanolichidae * Canestrinioidea (> 100 genera, > 300 species) ** Chetochelacaridae ** Lophonotacaridae ** Canestriniidae ** Heterocoptidae * Hemisarcoptoidea (50 genera, > 200 species) ** Chaetodactylidae ** Hyadesiidae ** Carpoglyphidae ** Algophagidae ** Hemisarcoptidae ** Winterschmidtiidae * Glycyphagoidea (> 70 genera, > 150 species) ** Euglycyphagidae ** Chortoglyphidae ** Pedetropodidae ** Echimyopodidae ** Aeroglyphidae ** Rosensteiniidae ** Glycyphagidae * Acaroidea (> 120 genera, > 500 species) ** Sapracaridae ** Suidasiidae ** Lardoglyphidae ** Glycacaridae ** Gaudiellidae **

Acaridae The Acaridae are a family of mites in order Sarcoptiformes. Distribution There are several acarid genera with cosmopolitan distributions, such as ''Acarus', Sancassania'' and ''Tyrophagus''. There are even ''Tyrophagus'' found in Antarctic ...

(> 110 genera, > 400 species) * Hypoderoidea ** Hypoderidae ;

(> 600 genera, > 2,000 species) * Pterolichoidea (> 200 genera, > 500 species) ** Oconnoriidae ** Ptiloxenidae ** Pterolichidae (> 100 genera, c. 300 species) ** Cheylabididae ** Ochrolichidae ** Gabuciniidae ** Falculiferidae ** Eustathiidae ** Crypturoptidae ** Thoracosathesidae ** Rectijanuidae ** Ascouracaridae ** Syringobiidae ** Kiwilichidae ** Kramerellidae * Freyanoidea (> 30 genera, c. 50 species) ** Freyanidae ** Vexillariidae ** Caudiferidae *

(> 200 genera, c. 700 species) ** Heteropsoridae ** Analgidae ** Xolalgidae ** Avenzoariidae ** Pteronyssidae ** Proctophyllodidae ** Psoroptoididae ** Trouessartiidae ** Alloptidae ** Thysanocercidae ** Dermationidae ** Epidermoptidae ** Apionacaridae ** Dermoglyphidae **

Laminosioptidae Laminosioptidae is a family of 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 ...

** Knemidokoptidae ** Cytoditidae * Pyroglyphoidea (26 genera, > 50 species) ** Pyroglyphidae ** Turbinoptidae * Psoroptoidea (c. 160 genera, > 600 species) **

Psoroptidae Psoroptidae is a family of parasitic mites, which are long and live on the surface of the skin, rather than burrowing into it. These mites affect various species, including cats, dogs, rabbits, cattle, sheep, and horses, causing skin inflammatio ...

** Galagalgidae ** Lobalgidae ** Myocoptidae ** Rhyncoptidae ** Audycoptidae **

Listrophoridae Listrophoridae is a family of mites in the suborder Psoroptidia of the order Sarcoptiformes. The family contains small, long mites specialized for grasping the hairs of mammals. North American genera include: *'' Aplodontochirus'' *'' Chirodiscoi ...

** Chirodiscidae ** Atopomelidae ** Chirorhynchobiidae ** Gastronyssidae ** Lemurnyssidae ** Pneumocoptidae **

Sarcoptidae The Sarcoptidae family of mites contains the genus ''Sarcoptes''. Sarcoptic mange Mange is a type of skin disease caused by parasitic mites. Because various species of mites also infect plants, birds and reptiles, the term "mange", or colloqu ...

* ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'' (16 genera, 17 species) ** Ptyssalgidae *** '' Ptyssalges major'' (Trouessart, 1887) ** Psoralgidae

''incertae sedis''

Troglotacaridae * '' Troglotacarus hauseri'' Fain, 1977

References

{{Taxonbar, from=Q1946789 Sarcoptiformes