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Mites or Acari

Common names: mites, ticks

Probability of encounter: high

Quarantine importance: numerous important pests of crops, livestock, wildlife, native flora, and humans.

Taxa most similar to mites: Ricinuleids have a cucullus and opisthosomal segmentation.  Opilionids have opisthosomal segmentation.

Morphology

Normal adult length: <1 mm, range 0.080 - 20 mm
Body tagmata: capitulum (= gnathosoma), idiosoma
Eyes: +/- 1-2 median ocelli; +/- 1-2 pairs lateral ocelli
Antennae: absent
Mouthparts: 2-3 segmented chelicerae; pedipalps (palps) with 1-5 free segments; pedipalpal coxae fused into subcapitulum
Legs: 1-4 pairs, typically 3 pairs in larvae, 4 pairs in nymphs and adults (rarely 2 pairs, 1 pair)
Distinguishing features: capitulum, loss of visible body segmentation

 

Diversity: 2-3 superorders, 5-6 orders, 450-500 families: 55,000 described species, >1,000,000 spp.

Tree of Life - http://tolweb.org/tree?group=Acari&contgroup=Arachnida

Krantz, G.W. 1978. A Manual of Acarology. Oregon State University Bookstores: Corvallis.

Walter, D.E. and Proctor, H.C.  1999.  Mites: Ecology, Evolution and Behaviour. University of NSW Press, Sydney and CABI, Wallingford.

Mite Classification - The Acari: a Taxonomic Framework