Trombidiformes

Superorder Acariformes

  Order Trombidiformes

 Suborders: Sphaerolichida, Prostigmata

    

Common names: trombidiform mites, trombidiformans, prostigmatans, sphaerolichids

 

Probability of Encounter: very high

 

Quarantine importance: Very high, all of the major plant parasitic mites belong to the Prostigmata as well as numerous important parasites of people, livestock, pets, wildlife and insects, including the presumed cause of Isle of Wight Disease in honeybees.  Many species are free-living predators or fungivores (including some pests in mushroom cultivation).

 

Diagnosis. Very small (0.08 mm long) to very large (16 mm) mites with a pair of stigmatal openings between the chelicerae or on the anterior margin of the idiosoma, sometimes associated with a chambered peritrematal system; gnathosoma either with the bases of the chelicerae exposed or partially consolidated into a stylophore or fully consolidated into a head-like capsule, capitulum sometimes retracted within the body; palps with 2-5 free segments, without a palp apotele; subcapitulum without a median groove or transverse rows of denticles; flagellate tritosternum absent; coxae fused to body wall, usually plate-like; chelicerae 2-segmented; prodorsum sometimes with 1-2 pairs of trichobothria; intercoxal region without sternal or genital shield elements, genital opening postcoxal; development: +/- hexapod prelarva, hexapod larva and 1-3 usually octopod nymphal stages (protonymph, +/- deutonymph, +/- tritonymph), rarely all stages are quadriped; genital opening develops gradually and sometimes associated with 1-2 pairs of genital papillae; larva sometimes with urstigmata; males sometimes with an aedeagus, never with modified chelicerae; female sperm receiving structures primary or secondary.

 

Similar mites.  Immature Mesostigmata may be confused with Prostigmata, but the lateral stigmatal openings should be easy to find except in larvae (which lack them).

 

Ecology & Distribution.  Cosmopolitan.  Although many species are free-living predators or fungivores, many lineages are parasitic on vertebrates and arthropods.  Many are phoretic on insects, often as adults and sometimes as specialized phoretomorphs.  As far as is known, all trombidiformans are fluid-feeders, but lordalychid Sphaerolichida sometimes have fungal spores in their guts.

 

References

Kethley JB.  1982.  Acariformes.  In: Parker, S.P. (ed.)  Synopsis and Classification of Living Organisms.  McGraw-Hill, New York, pp. 142-145.

Kethley JB.  1990.  Acarina: Prostigmata (Actinedida).  In DL Dindal (ed.)  Soil Biology Guide.  John Wiley & Sons, New York, pp. 667-756.

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.