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Astigmatina is a clade of
mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...
s in the order
Sarcoptiformes The Sarcoptiformes are an order (biology), order of mites 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 A ...
.
Astigmata Astigmatina is a clade of mites in the order Sarcoptiformes. 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. Astigm ...
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. Astigmatina is now made up of the two groups Acaridia and Psoroptidia, which have been suborders of the order Astigmata in the past. Astigmatina contains about 10 superfamilies and 76 families under Acaridia and Psoroptidia.


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 (how ...
(mouthparts) is usually exposed. They have a pair of
chelicerae The chelicerae () are the arthropod mouthparts, 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 ...
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 ...
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 temporary commensalistic relationship when an organism (a phoront or phoretic) attaches itself to a host organism solely for travel. It has been seen in ticks and mites since the 18th century, and in fossils 320  ...
(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. The ...
), 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 ( or aedeagi) is a reproductive organ of male arthropods through which they secrete sperm from the testes during copulation (zoology), copulation with a female. It can be thought of as the insect equivalent of a mammal's penis, th ...
in a usually postcoxal position. Females have a secondary
sperm Sperm (: sperm or sperms) is the male reproductive Cell (biology), 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 ...
-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 curren ...
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) 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 ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
and
algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
. 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 monophyletic lineage within the superfamil ...
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 human skin infestation by the tiny (0.2–0.45 mm) mite ''Sarcoptes scabiei'', variety ''hominis''. The word is from . The most common symptoms are severe itchiness a ...
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 infecti ...
. 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 ** Guanolichidae * Canestrinioidea (> 100 genera, > 300 species) ** Chetochelacaridae ** Lophonotacaridae ** Canestriniidae ** Heterocoptidae * Hemisarcoptoidea (50 genera, > 200 species) ** Chaetodactylidae ** Hyadesiidae ** Carpoglyphidae ** Algophagidae ** Hemisarcoptidae **
Winterschmidtiidae Winterschmidtiidae is a family of mites in the order Astigmata. Ecology The four subfamilies of Winterschmidtiidae have different habits: Ensliniellinae are associated with Hymenoptera; Winterschmidtiinae with wood-boring insects; Saproglyph ...
* Glycyphagoidea (> 70 genera, > 150 species) ** Euglycyphagidae ** Chortoglyphidae ** Pedetropodidae **
Echimyopodidae Echimyopodidae is a family of mites in the order Astigmata Astigmatina is a clade of mites in the order Sarcoptiformes. Astigmata has been ranked as an order or suborder in the past, but was lowered to the unranked clade Astigmatina of the cl ...
** 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''. Ecology Acaridae live in various habitats an ...
(> 110 genera, > 400 species) * Hypoderoidea ** Hypoderidae ; Psoroptidia (> 600 genera, > 2,000 species) * Pterolichoidea (> 200 genera, > 500 species) ** Oconnoriidae ** Ptiloxenidae **
Pterolichidae Pterolichidae is a family of mites belonging to the order Sarcoptiformes. Taxonomy The following genera are recognised in the family Pterolichidae: *''Aegothelichus'' *''Afrolichus'' *''Ambodrilus'' *''Anapodema'' *''Aniacarus'' *''Ani ...
(> 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 * Analgoidea (> 200 genera, c. 700 species) ** Heteropsoridae **
Analgidae Analgidae is a family of mites belonging to the order Sarcoptiformes The Sarcoptiformes are an order (biology), order of mites comprising over 15,000 described species in around 230 families. Previously it was divided into two suborders, Oriba ...
** Xolalgidae **
Avenzoariidae Avenzoariidae is a family of feather mites in the order Astigmata. There are at least 15 genera in Avenzoariidae. They are found on the feathers of aquatic birds, and in the case of one species, birds of prey. Genera These 15 genera belong to t ...
** Pteronyssidae ** Proctophyllodidae ** Psoroptoididae ** Trouessartiidae ** Alloptidae ** Thysanocercidae ** Dermationidae ** Epidermoptidae ** Apionacaridae ** Dermoglyphidae **
Laminosioptidae Laminosioptidae is a family of mites belonging to the order Sarcoptiformes The Sarcoptiformes are an order (biology), order of mites comprising over 15,000 described species in around 230 families. Previously it was divided into two suborders, ...
** Knemidokoptidae ** Cytoditidae * Pyroglyphoidea (26 genera, > 50 species) ** Pyroglyphidae ** Turbinoptidae * Psoroptoidea (c. 160 genera, > 600 species) ** Psoroptidae ** Galagalgidae ** Lobalgidae ** Myocoptidae ** Rhyncoptidae ** Audycoptidae ** Listrophoridae ** 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 colloq ...
* ''
incertae sedis or is a term used for a taxonomy (biology), 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