Prostigmata is a suborder 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 belonging to the order Trombidiformes, which contains the "sucking" members of the "true mites" (

Acariformes The Acariformes, also known as the Actinotrichida, are the more 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 speci ...

). Many

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

are notorious pests on

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s. Well-known examples of prostigmatan plant

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

s are species of the gall mites ( Eriophyidae, e.g. the redberry mite '' Acalitus essigi''), Tarsonemidae (e.g. the cyclamen mite, '' Steneotarsonemus pallidus''), and the spider mites of the Tetranychidae (e.g. the two-spotted spider mite, '' Tetranychus urticae''). Other Prostigmata live as parasites on

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s (e.g. ''

Demodex ''Demodex'' is a genus of tiny mites that live in or near hair follicles of mammals. Around 65 species of ''Demodex'' are known. Two species live on humans: ''Demodex folliculorum'' and ''Demodex brevis'', both frequently referred to as eyelash ...

'' mites of the Demodecidae) or

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s (e.g. '' Polydiscia deuterosminthurus'' of the Tanaupodidae or the honeybee tracheal mite, '' Acarapis woodi'', of the Tarsonemidae). There are also some forms (e.g. Smarididae) that are

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s of small invertebrates – including smaller Prostigmata – yet others have a more varied lifestyle (e.g. Tydeidae) or switch their food sources as they mature (e.g. Erythraeidae). The suborder also includes the family Halacaridae (marine mites). Some of the Prostigmata parasitizing vertebrates are of medical relevance due to causing skin diseases in humans. These include for example harvest mites ("chiggers") of the Trombiculidae.

Description

Prostigmata are usually 0.1–2 mm long, though some giant red velvet mites can reach 16 mm. They have a range of different body forms and colours. As mites, most of them have eight legs (six in their larval stage). However, the

Eriophyoidea Eriophyoidea are a superfamily of herbivore, herbivorous mites. All post-embryonic instars lack the third and fourth pairs of legs, and the respiratory system is also absent. The taxonomy of this group has always been confused. There were famili ...

instead have four legs, all positioned at the front of a long, worm-like body. The name "Prostigmata" comes from mites of this group having spiracles (stigmata) on the prodorsum, usually between the chelicerae or on its lateral margins.

Habitat

Many prostigmatans live in soil. These occur in soils as varied as agricultural fields, burned

prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...

s, tidal marshlands, drained lake beds with

algal bloom An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in fresh water or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompass ...

s, and

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

soils. Other prostigmatans are aquatic. The group includes Hydrachnidia, commonly known as the water mites. Hydrachnidia live in many kinds of freshwater habitats, including lentic (e.g. lakes, ponds), lotic (e.g. rivers, streams), springs and interstitial waters. Also in the Prostigmata are family Halacaridae, which are mostly marine. Other habitats of Prostigmata include caves, algae, mosses, lichens, shrubs and trees.

Diet

Prostigmata have a wide range of diets, including species that are predators,

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s, fungivores, microbivores and

parasites Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

. Among the soil-dwelling Prostigmata, the smaller predatory species have

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

s as an important part of their diet. They may also feed occasionally on fungi, piercing fungal

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

e using stylet chelicerae. Larger predatory species, such as members of

Bdelloidea Bdelloidea (from Greek language, Greek βδέλλα, ''bdella'' 'leech') is a Class (biology), class of rotifers found in freshwater habitats all over the world. There are over 450 described species of bdelloid rotifers (or 'bdelloids'), disti ...

and Trombidoidea, feed on other arthropods or their eggs.

Systematics and taxonomy

The Prostigmata make up the bulk of the acariform

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Trombidiformes, which also contains the minor and quite ancient lineage Sphaerolichida. The trombidiform mites are possibly the most promising approach to untangle the

systematics Systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: phylogenetic trees, phylogenies). Phy ...

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

and

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

of the notoriously complex Acariformes. Trombidiformes and the other acariform clade, Sarcoptiformes, were formerly considered

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

s but this does not allow for a sufficiently precise classification of the mites and is adjusted in more modern treatments. They contain a few of the little-known " Endeostigmata" – apparently an assemblage of several specialized but only distantly related lineages – which for the most part appear to be Sarcoptiformes. In addition, the Trombidiformes include the bulk of the presumed group of mites called "Actinedida". This

taxon In biology, a taxon (back-formation from ''taxonomy''; : 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 name and ...

is still commonly encountered in systematic treatments. However, modern

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

studies time and again fail to find any

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group corresponding to the "Actinedida". Thus, they appear to be an

evolutionary grade A grade is a taxon united by a level of morphological or physiological complexity. The term was coined by British biologist Julian Huxley, to contrast with clade, a strictly phylogenetic unit. Phylogenetics The concept of evolutionary grades ...

rather than an evolutionary lineage, united not by their

apomorph In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ha ...

ies but by the lack of such characters that have evolved after the Acariformes separated from the Parasitiformes. Thus, the "Actinedida" seem to be a massively

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

" wastebin taxon", uniting all Acariformes that are not "typical" Oribatida and Astigmata. The Prostigmata present their own taxonomic and systematic problems even in the redefined

delimitation Electoral boundary delimitation (or simply boundary delimitation or delimitation) is the drawing of boundaries of electoral precincts and related divisions involved in elections, such as Federated state, states, counties or other municipalities ...

. They are variously subdivided into the Anystina and Eleutherengona, and Eupodina. The delimitation and interrelationships of these groups are entirely unclear; while most analyses find one of the latter two but not the other to be a subgroup of the Anystina, neither of these mutually contradicting hypotheses is very robust; possibly this is a simple error because phylogenetic software usually fails in handling non-

dichotomous A dichotomy () is a partition of a set, partition of a whole (or a set) into two parts (subsets). In other words, this couple of parts must be * jointly exhaustive: everything must belong to one part or the other, and * mutually exclusive: nothi ...

phylogenies. Consequently it may be best for the time being to consider each of the three main prostigmatan lineages to be equally distinct from the other two, not including either Eleutherengona or Eupodina in the Anystina in accord with the traditional view – the

Anystina are here considered the largest possible clade containing the

Anystidae Anystidae is a family (biology), family of mites, based on the genus ''Anystis''. The family has a cosmopolitan distribution, and contains "generalist predators found on a variety of habitats". References External links

* Trombidiforme ...

but no taxon assigned to the other two suborders.

Currently accepted taxonomy

Catalogue of Life The Catalogue of Life (CoL) is an online database that provides an index of known species of animals, plants, fungi, and microorganisms. It was created in 2001 as a partnership between the global Species 2000 and the American Integrated Taxono ...

and

Integrated Taxonomic Information System The Integrated Taxonomic Information System (ITIS) is an American partnership of federal agencies designed to provide consistent and reliable information on the taxonomy of biological species. ITIS was originally formed in 1996 as an interagenc ...

accept the following taxonomy for Prostigmata, including four infraorders:

Anystina

* Superfamily Adamystoidea * Superfamily Allotanaupodoidea * Superfamily Amphotrombioidea * Superfamily

Anystoidea Anystoidea is a superfamily of mites in the order Trombidiformes. References Further reading

* * * Trombidiformes {{trombidiformes-stub ...

* Superfamily Arrenuroidea * Superfamily Caeculoidea * Superfamily Calyptostomatoidea * Superfamily Chyzerioidea * Superfamily Erythraeoidea * Superfamily Eylaoidea * Superfamily Hydrachnoidea * Superfamily Hydrovolzioidea * Superfamily Hydryphantoidea * Superfamily Hygrobatoidea * Superfamily Lebertioidea * Superfamily Paratydeoidea * Superfamily Pomerantzioidea * Superfamily Stygothrombioidea * Superfamily Tanaupodoidea * Superfamily Trombiculoidea * Superfamily Trombidioidea * Superfamily Yurebilloidea

Eleutherengona

(Also known as Eleutherengonides) * Superfamily Cheyletoidea * Superfamily Cloacaroidea * Superfamily Dolichocyboidea * Superfamily Heterocheyloidea * Superfamily Myobioidea * Superfamily Pterygosomatoidea * Superfamily Pyemotoidea * Superfamily

Raphignathoidea Raphignathoidea is a superfamily (taxonomy), superfamily of the Acari (mite) order (biology), order Trombidiformes, comprising 1087 species in 62 genera and 12 Family (biology), families. Morphology Adult Raphignathoidea are generally oval or ...

* Superfamily Scutacaroidea * Superfamily Tarsocheyloidea * Superfamily Tarsonemoidea * Superfamily Tetranychoidea * Superfamily Trochometridioidea

Eupodina

* Superfamily

* Superfamily Eupodoidea * Superfamily Halacaroidea * Superfamily Tydeoidea

Labidostommatina

* Superfamily Labidostommatoidea: monotypic family Labidostommatidae

References

{{Authority control Trombidiformes Arthropod suborders