Mesostigmata

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Taxonomy

updated 2025

Diagnostic characters

• Uropodid mites with a large, flower-like or mushroom-shaped membranous excrescenceexcrescence:
  (1) a brush-like, dendritic or otherwise elaborated processes produced from openings in the movable digit in trigynaspid and some microgyniine Mesostigmata; (2) an encrusted covering or outgrowth-like structure. 
  on the tip of the fixed digitfixed digit:
  the distal extension of the middle article of the chelicera; usually bearing teeth and a distal hook and opposed to the movable digit in chelate-dentate forms, but often regressed; in Mesostigmata the fixed digit may bear the pilus dentilis.
  
• Sclerotized node present
• Pilus dentilispilus dentilis:
  (pl. pili dentilis) a seta-like or membranous sensory organ inserted ventrolaterally on the fixed digit of the chelicera of many Mesostigmata.
  absent
• Pedofossaepedofossa:
  (pl. pedofossae) (= fossae pedales, fovae pedales) recesses into which the legs can be withdrawn.
  (fovae pedalesfova pedales:
  (pl. = fovae pedales) a pedofossa, a pit in the cuticle into which the legs can be withdrawn in some Mesostigmata, especially Uropodidae.
  ) and metapodal lines present
• Peritreme sinuatesinuate:
  with a winding, snake-like, or wave-like form, as in the peritremes of some Uropodidae (Mesostigmata) or the setae of various mites.
  
• Dorsaldorsal:
  relating to the upper or back side; opposed to ventral.
  shield entireentire:
  a shield or sclerite with a continuous margin without incisions.
  

Similar taxa

Many uropodoids are similar in general appearance, but the flower-like process on the chelicera is unique to Uroactinea. The confamilial genus Chiropturopoda has a similar process that is not fringed and looks more like a mushroom.

Ecology and distribution

Uroactinia agitans (Banks) may reach high numbers in commercial worm beds or other accumulations of organic matter.

References

• Ainscough 1981Ainscough 1981:
  Ainscough BD. 1981. Uropodine studies. I. Suprageneric classification in the cohort Uropodina Kramer, 1882 (Acari: Mesostigmata). International Journal of Acarology 7: 47–56.
• Karg 1989aKarg 1989a:
  Karg W. 1989a. Acari (Acarina), Milben Unterordnung Parasitiformes (Anactinotrichaeta) Uropodina Kramer, Schildkrötenmilben. Die Tierwelt Deutschlands 67: 1-203.
• Krantz and Ainscough 1990Krantz and Ainscough 1990:
  Krantz GW and Ainscough B. 1990. Mesostigmata. pp. 583-665. In: Dindal DL, ed. Soil biology guide. John Wiley & Sons, Brisbane.
• Wisniewski and Hirschmann 1993Wisniewski and Hirschmann 1993:
  Wisniewski J and Hirschmann W. 1993. Gangsystematik der Parasitiformes. Teil 548. Katalog der Ganggattungen, Untergattungen, Gruppen und Arten die Uropodiden der Erde. Acarologie, Schriftenreihe für Vergleichende Milbenkunde 40: 1-220.