Acaridia

Classification

Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Subclass: Acari
Superorder: Acariformes
Order: Astigmata
Suborder: Acaridia

Pronunciation

How to pronounce Acaridia: //ˌækəˈrɪdiə//

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Summary

Astigmatina is a diverse clade of mites characterized by their soft bodies and varied ecological roles. They are predominantly found in moist conditions and can be both harmful parasites and beneficial organisms.

Physical Characteristics

Astigmatan mites are usually soft-bodied and range in color from white to brownish, rarely tan, and are well-sclerotised. They measure 0.15 to 2.00 mm in length. They lack stigmatal openings and have an exposed gnathosoma. Their chelicerae are typically 2-segmented and chelate-dentate. The presence of opisthosomal glands is common and well-developed.

Identification Tips

Look for soft-bodied mites ranging from white to brownish. Examine the number of legs; larvae have six legs while nymphs and adults have eight legs. The presence of a pair of chelicerae that are usually chelate-dentate is also notable.

Habitat

Astigmatina show a wide range of ecological strategies, occurring in various environments including wet substrates (decaying plant tissue, dung, mud, and tree holes), mammal nests, human houses, and stored foods. Some are associated exclusively with birds or their nests.

Diet

Many species are microbe feeders, while some species with chelate chelicerae can feed on vegetable material, fungi, and algae. Parasitic species feed on hosts, including exudates of beetles and mammal tissues.

Life Cycle

Astigmatina undergo multiple life stages: larvae (hexapod), nymphs, and adults (octopod). The deutonymph stage can be heteromorphic and adapted for phoresy or survival under stress conditions. The genital structures vary, with different structures in protonymphs, tritonymphs, and adults.

Reproduction

Males possess an aedeagus typically in a postcoxal position, while females have a bursa copulatrix for sperm storage.

Ecosystem Role

Astigmatina play a role in ecosystems as decomposers, feeding on organic material, and some can be beneficial as they predate pests like scale insects.

Economic Impact

Astigmatina can cause damage to stored products and contribute to allergic reactions. Parasitic species are responsible for diseases like scabies and mange, while some are pests of seedling crops.

Health Concerns

Certain species are known to cause diseases such as scabies and mange.

Evolution

Astigmatina are part of the clade Desmonomatides and have evolved to exhibit various ecological strategies compared to their oribatid ancestors, moving beyond soil to more diverse habitats including living in association with vertebrates.

Similar Taxa

Misconceptions

It's often assumed that all mites are harmful; however, many species within Astigmatina can be beneficial by controlling pest populations.