Oribatida

Superorder Acarifomes

Order Sarcoptiformes

Supercohorts: Palaeosomatides, Enarthronotides, Parhypsomatides, Mixonomatides, Desmonomatides (including Cohorts Brachypylina and Astigmatina)

 

Common names: oribatid mites, moss mites, armored mites, cryptostigmatans, astigmatans, acarids

 

Probability of Encounter: very high

 

Quarantine importance: High, but almost entirely because of the Astigmatina (previously treated as a suborder).  Most traditional oribatid mites are of little interest to quarantine: most are fungivores or detritivores, only a few are minor pests of plants and none are significant parasites of animals.  Some oribatids, however, may disperse fungal spores and other microbial propagules.  In contrast, the cohort Astigmatina contains many important parasites of people, livestock, pets, wildlife and insects, as well as many fungivores and scavengers that are pests in stored products and homes.

 

Diagnosis. Small (0.100 mm long) to medium (2.0 mm) mites without typical stigmatal openings (some have secondarily derived brachytracheae), rarely with expansive plastron-like structures in aquatic species; gnathosoma  with the bases of the chelicerae exposed, but often withdrawn into a camerostome; palps with 2-5 free segments, without a palp apotele; subcapitulum without a median groove or transverse rows of denticles; toothed to quadrate rutella usually present; flagellate tritosternum absent; coxae fused to body wall, usually plate-like or completely assimilated into the body wall (epimeres); chelicerae 2-segmented (rarely with additional remnant basal segment); prodorsum with 0-1 pair of trichobothria; intercoxal region without sternal or genital shield elements, genital opening postcoxal; development: +/- hexapod prelarva, hexapod larva and 2-3 octopod nymphal stages (protonymph, +/- deutonymph, tritonymph); genital opening develops gradually and usually associated with 1-3 pairs of genital papillae; larva usually with urstigmata; males sometimes with an aedeagus, never with modified chelicerae; female sperm receiving structures primary or secondary.

 

Similar mites.  Some adult Mesostigmata and Prostigmata are heavily sclerotized and might be confused with oribatid mites.  However, heavily sclerotized oribatid mites usually have rutella and lack stigmatal openings.  Additionally, heavily sclerotized Mesostigmata usually have well developed tritosterna and horn-like corniculi.

 

Ecology & Distribution.  Cosmopolitan.  Although most species are free-living fungivores, many astigmatine lineages are parasitic on vertebrates and arthropods.  Many Astigmatina are phoretic on insects as heteromorphic deutonymphs (hypopi).  Most oribatids are particulate-feeders, but some feed on fluids or very fine particulate matter.

 

References

Balogh J.  1972.  The Oribatid Genera of the World (Akadémiai Kiadó, Budapest) pp 1-188 + Plates 1-71.

Balogh J & Balogh P. (1988).  Oribatid Mites of the Neotropical Region. Volume I, 335 pp., volume II, 333 pp. (Elsevier, Amsterdam).

Colloff M & Halliday B.  1998.  Oribatid Mites.  A Catalogue of Australian Genera and Species.  Monograph on Invertebrate Taxonomy Vol. 6.  CSIRO Publications: Melbourne.

Gilyarov MS & Krivolutsky DA (eds)  1975.  Handbook for the Identification of Soil-inhabiting Mites, Sarcoptiformes.  Zoological Institute of the Academy of Sciences: Petrograd [In Russian]

Hunt G, Colloff MJ, Dallwitz M, Kelly J. & Walter DE.  1998.  An Interactive Key to the Oribatid Mites of Australia.  CSIRO Publishing, Collingwood, Victoria.  (Compact Disk and User Guide)

Krantz GW.  1978.  A Manual of Acarology.  OSU Bookstores: Corvallis.

Walter DE and Proctor HC.  1999.  Mites: Ecology, Evolution and Behaviour. University of NSW Press, Sydney and CABI, Wallingford.